Growing Weed From Seed

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How long does it take to germinate cannabis seeds? When to transplant seedlings? When to start vegging and flowering? Grow your knowledge about the lifecycle of the cannabis plant. A growing number of experts are making a business out of teaching people how to grow their own pot. Here's what to know to get started. For many, growing cannabis in a greenhouse is simpler than creating an indoor grow room. Greenhouse growers find it easier than growing cannabis outdoors.

Cannabis growth stages breakdown

Growing cannabis can seem easier when the process is broken down into the 4 main cannabis growth stages. These are the cannabis seed germination, seedling, veg and bloom. At each stage the requirements for nutrients, light and water will vary. The experienced cannabis grower will know how to give the right environmental conditions at each of the stages of cannabis growth. However cannabis plants will always teach you something new to improve the way you grow. Dive into this guide to learn all you should know about the life cycle of cannabis!

Summary:
How long is a cannabis full grow cycle on average?
Cannabis germination stage (2-10 days)
Cannabis seedling stage (2-3 weeks)
Cannabis vegetative stage (3-15 weeks)
Cannabis flowering stage (7-14 weeks)
Other important cannabis life cycle considerations

How long is a cannabis full grow cycle on average?

There are 4 main stages of the cannabis life cycle as it transitions from seed to harvest. Germination is often defined as the time taken from planting the cannabis seed to the point where it has produced it’s first cotyledon leaf pair. These are the first ‘baby’ (non-serrated) leaf set which is formed as the seed germinates.

Cannabis growth stages Average duration
Germination stage 2-10 days
Seedling stage 1-3 weeks
Vegetative stage 1-15 weeks
Flowering stage 7-14 weeks*

The cannabis plant life cycle for a fast growing autoflower seed variety such as as Auto Blueberry or Auto Blackberry Kush could be as little as 9 weeks from seed to harvest.

Or it could be a 6 months cannabis life cycle for an outdoor seed variety. The indoor cannabis grower has full control over their plants and the environment. This allows indoor feminised seed growers to dictate the length of vegetative growth, which in turn will affect final plant size, yield and overall life cycle.

The length of the cannabis full grow cycle will depend on your choice of cannabis seeds (autoflower seeds vs feminised seeds) and whether you grow them indoors or outdoors.

Related:
Autoflower seed vs feminised seed outdoor cannabis growing

Cannabis germination stage (2-10 days)

Cannabis seeds are typically small, hard and dry. The colours vary from light to dark brown. The first cannabis plant stages take place after the seed has germinated. During seed germination the shell of the seed is initially softened by the moist germination conditions. It’s important to provide moist, but never soaked, conditions for cannabis seed germination in order to achieve maximum germination rates from your precious seeds.

Cannabis seeds should be germinated in dark conditions and don’t need any nutrients initially. Water is sufficient for the first few days. The tap root will emerge from the cannabis seed and grow downwards. The first set of cotyledon leaves will emerge and the cannabis grow cycle has begun! Note that these leaves don’t have the ‘normal’ serrated edges which you will see on all subsequent leaves. As all this is happening the cannabis root system starts to form.

It can take around 2-10 days for seed germination to occur. Occasionally, cannabis seeds can take up to 2 weeks to germinate. Eventually you will see the first set of ‘true’ cannabis leaves with serrated edges appear. For many growers, this represents the end of the cannabis germination stage and the start of the seedling stage.

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How long does it take to germinate cannabis seeds?

It can vary from one cannabis seed to another. Usually you can expect seeds to germinate somewhere around 2-10 days after you begin the germination process. Occasionally you can get cannabis seeds to germinate in just one day. Sometimes it can take around 2 weeks. But usually you can expect to wait around 2-10 days for your cannabis seeds to germinate.

Can you speed up the germination process?

Not really. You need to provide good cannabis seed germination conditions and then wait for nature to do her work. If you have bought good quality cannabis seeds from a proven supplier than you can expect cannabis seed germination rates of 90%+.

Many growers have accidentally killed their plants during germination by trying to speed things up by a day or two. It definitely isn’t recommended to e.g. sand-paper your seeds to reduce the shell thickness in an attempt to speed up germination. Nor is it recommended to try to force the shell off the plant during germination. Instead, just be patient and allow the cannabis genetics to do their work.

When to transplant cannabis seedlings?

If you have germinated your cannabis seeds with the moist cotton pad method then you will simply place the germinated seedlings in your grow medium (e.g. soil or coco fibre) or your grow system (e.g. DWC or NFT hydroponic system).

Many growers that use e.g. autoflowering cannabis seeds will simply put their seedling into the final grow container. This avoids the need to repeatedly transplant the seedling to progressively larger containers. In the case of an autoflower strain with a limited lifetime, this process allows the auto to focus all the available time on growth. No plant time is spent adapting during repeated transplants, allowing your auto to reach maximum potential.

Those that grow photoperiod feminised seeds indoors can choose when the blooming process starts simply by reducing daylight hours. That gives them more time to spend progressively potting up and transplanting into gradually larger containers if they wish.

Related:
Cotton pads germination video tutorial

Cannabis seedling stage (2-3 weeks)

For the next 2-3 weeks after germination, the cannabis seedling will grow. The cannabis root system is essential for healthy growth and development. Experienced growers aim to deliver fully optimised grow conditions in order to maximise root growth. Give the roots waterlogged cold soil and they won’t grow well, this may result in a permanently stunted plant.

Above ground, the cannabis seedling will continue to grow. With each new set of leaves you may notice progressively more ‘blades’ or fingers on the leaves. Initially you may see 3 fingers, then 5 or 7 etc. During the life cycle of cannabis, the seedling needs less water and nutrition than it does in subsequent veg growth and flowering stages. This is one of the most delicate cannabis growing stages. The seedling needs little water and minimal nutrients.

If growing in light mix soil there you may not need to consider any grow nutrients until a week after the first set of serrated leaves emerge. Generally, a light mix soil has enough nutrition for the first couple of weeks after cannabis seed germination. After that many growers use root stimulator and grow nutrients.

If you are growing in hydroponics or coco fibre you may already be carefully using very light nutrients on young seedlings. You may prefer to use specialist low strength seedling nutrients at this stage. The goal is to keep the cannabis seedling in the nutrient sweet spot without over feeding or underfeeding. If seedlings are given excessive nutrients it can ‘burn’ the plant, permanently limiting future growth.

Related:
Everything you need to know about cannabis roots

How long does the cannabis seedling stage last?

Many growers consider the first 2-3 weeks after germination to be the cannabis seedling stage. These are the first couple of weeks where the seedling is most vulnerable. The seedling may only be a few inches/cm tall with a couple of sets of true (non-cotyledon) leaves.

Lighting levels don’t need to be particularly intense for cannabis seedlings, for the technically minded PPFD levels of 200-400 should be adequate. Many use T5 fluorescent tubes for cannabis seedling lighting. The delicate young seedling leaf tissue can be damaged by the intense light levels which you will need in later cannabis flowering stages.

If you do see your cannabis seedlings stretching a little too much it can help to reduce the distance between the plants and the light. With higher light intensities, the stretching should reduce. If your seedling suffer elongated stems you can gently prop up your seedling with some small wooden supports, such as toothpicks (or similar)

What does a healthy cannabis seedling look like?

You can expect a short, squat plant. The cotyledon leaves will be small in comparison to the emerging ‘true’ leaves and you will notice new leaf sets emerging from the central growing point of your plant (the ‘apex’). The colour should be a vibrant green. Any signs of yellowing is a signal that something is wrong. If your seedling has brown leaf tips it’s a sign that you have overfed your seedlings and ‘burned’ the plant. This is never a good sign and can temporarily or permanently restrict future growth.

If you have a healthy cannabis seedling it will have all the basics in place for future growth. The roots should have the space and nutrients/minerals required to grow a larger frame. The leaves will be ready to grow and absorb more light which will power future photosynthesis. Your plant is set for vegetative growth and will be ready for more light, nutrients and water.

Autoflower seed growers may already have their plant in the final grow container at this stage.

Related:
Top 10 germination and seedling mistakes

Cannabis vegetative stage (3-15 weeks)

Vegetative growth is the indoor cannabis growing stage where roots, branches and leaves grow but no buds are formed. Indoor growers often use 18-24 hours of daily light whether they are using autoflower seeds or photoperiod feminised cannabis seeds.

During vegetative growth the cannabis plants gradually grow in both height and width. Nitrogen rich nutrients are particularly useful in the vegetative growth stage. The first sets of cannabis leaves grow gradually larger and new leaf sets are formed. As the plant grows it’s requirements for nutrients, water and light will all increase. Light levels can be increased from around 200 PPFD to nearer 400-600 PPFD – your light manufacturer should be able to detail the PPFD levels at various hanging heights.

How long should a cannabis plant stay in veg?

Those growing photoperiod feminised cannabis seeds can select the length of the vegetative growth stage. Often it’s around 4-6 weeks for many growers. But some growers, e.g. SCROG growers (Screen Of Green method), prefer very long periods of ‘veg’ growth, in extreme cases up to 15 weeks or so. However, SOG growers (Sea Of Green method), may not give their plants any veg growth and instead put them straight into bloom conditions.

Those growing autoflower seeds will not be able to dictate the length of the vegetative growth phase. Instead the autoflower seed genetics will determine the point at which it automatically transitions from veg to bloom. It does this without any change or alteration to the light cycle. Autoflowering cannabis seeds grow from seed to harvest under the same light cycle, typically 20 hours of daily light. Photoperiod feminised cannabis strains only commence bloom when indoor light hours are reduced to 12 per day.

Related:
SOG vs SCROG cannabis growing

How does a healthy cannabis plant in veg look like?

Much depends on the length of time the plant has been in the vegetative growth stage for. A feminised strain with 15 weeks of veg growth could have filled a very large SCROG screen. Whereas an autoflower plant in veg may be perhaps 10-20cm tall, perhaps 3 weeks old and ready to start stretching once bloom begins. Much depends on your cannabis genetics and grow style. But you can expect to see a medium-sized plant with healthy green foliage, but no buds.

Why does my cannabis plant want to flower in the vegetative stage?

The cannabis flowering stage follows veg growth. Cannabis plants are genetically geared towards bloom. It’s the only chance for cannabis to produce seeds and produce the next generation of plants. You may see pre-flowers at the nodes between the stem and branches. Autoflower genetics don’t hold back. As soon as they are ready, autos start to transition from veg to bloom. During this process the auto exhibits features of both veg and bloom.

Cannabis flowering stage (7-14 weeks)

During the cannabis flowering stages, the female plant produces buds and resin. The flowering stage follows the vegetative growth stage. When growing autoflowering cannabis seeds, the transition from the vegetative stage to the flowering stage happens automatically (hence the name, autoflowering).

When growing photoperiod feminised cannabis seeds, bloom begins indoors when the daily light hours are decreased to 12. Outdoors, feminised strains sense the shortened daylight hours as autumn/fall approaches and bloom begins. However if you are growing at equatorial regions the plants can sense the short days immediately.

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During the cannabis flowering stage, the plant will require gradually increased levels of nutrients and water. Phosphorus will be required in greater quantities as the plant biochemistry changes. During the cannabis flowering stage the plant biomass can increase dramatically.

Intense light levels can be used in bloom, often with PPFD levels of 600-900. More light can deliver heavier yields. Some professional cannabis growers used PPFD levels of around/over 1000 and may also supplement with Carbon Dioxide to further boost yields.

The length of the flowering stage depends on the genetics. 7 weeks of bloom is required by fast flowering indica strains such as Bubba Island Kush seeds. But a slow blooming Haze may require upwards of 14 weeks in bloom.

The following cannabis flowering stages are shown in week by week pictures, below.

How to tell if a cannabis plant is ready to bloom?

Knowing when your plant is ready to be flipped from veg growth to bloom is one of the most important decisions you will make. But first you may wish to consider a few points related to the timing of the cannabis flowering stage.

• The height of your grow room may be a limiting factor. If you have restricted vertical growing space you may prefer to have minimal veg time.

• Are you growing indica or sativa cannabis seeds? Sativa strains may stretch dramatically during bloom. Take this into account when deciding if your cannabis plant is ready to bloom.

• Growing clones or seeds? Clones don’t always have well established root systems and can take a while to create one before being flipped into bloom.

• Outdoor plants can also be forced into early bloom if you have a greenhouse equipped with blackout blinds. Otherwise, they will choose their own moment to bloom as daylight hours shorten.

• Which growing method are you using? If using the SCROG method you may wish to wait and give the plant a long veg stage. If using the SOG method you may want to offer minimal veg time or even none at all and grow from seed to harvest under 12/12 light

• Which region/climate are you growing in? If you’re growing in tropical equatorial regions you may want the most sativa dominant strains with the most stretch. That’s because the plants go into flowering more-or-less immediately. In more temperate climates, the plants commence bloom as daylight hours shorten. For Northern Hemisphere growers (Europe, USA etc) this often happens around August.

Related:
Power Plant grown from seed to harvest under 12/12 light

How long does it take for cannabis to start blooming after switching the light cycle?

Once you switch the light cycle to 12/12 (12 hours of daily light) the plant undergoes plant hormone changes as it senses the shorter days.

The plant hormones cause the plant to prepare for bloom. Over the following week or so you will see the changes on the cannabis plant as she gets ready to stretch and produce flowers. You may see female pre-flowers producing a couple of pistils (hairs) at the node between the stem and a branch.

However you can expect to wait 1-2 weeks before you start to see flowers starting to appear. With certain sativa and hybrid strains it can take 3-6 weeks before any significant flower formation.

How does a healthy cannabis plant in flowering look like?

Initially you may notice areas of light green foliage at the eventual points where buds will eventually form. You may also notice the plants stretching, with increased internodal distance.

Growers monitor their cannabis flowering stages week by week. Some like to consider the cannabis flowering stage as 3 separate mini-phases; early bloom, mid bloom and late bloom. As your cannabis plant flowers the weight of buds and resin should increase as harvest point approaches.

During the cannabis flowering stage you will notice that your plant appetite for nutrients reaches maximum as it produces bigger buds and more cannabinoid-containing resin. The ratio of required nutrients will change too. Less Nitrogen (N) is required and increasing amounts of Phosphorus (P) and Potassium (K) are needed to support heavy harvests of compact flowers.

During the first few weeks of bloom your plant will stretch. A sativa may stretch to 2-3 times the height it was at the end of veg. You will see increasing amounts of pistils being produced and the buds start to form and eventually fatten up. After around 5 weeks of bloom the cannabis plants have generally stopped stretching and the buds start to get larger.

As harvest approaches, the pistils start appearing as orange rather than white.

How to tell when your cannabis buds are ready for harvest?

Your cannabis seed supplier should give an indication of the approximate length of the flowering stage. This is a guideline rather than a fixed rule and it may indicate the typical earliest harvest point rather than the recommended harvest time.

Environmental conditions and the specific phenotype will determine the actual harvest date. In addition, you may have a preference for early, mid or late harvested buds.

There are various cannabis bud growth stages. They start small and gradually pack on weight and resin as they grow. Some growers like the slightly heavy effects (and more generous yields) offered by allowing the buds a week or two extra in bloom.

There are different cannabis trichomes stages to consider. Immature buds tend to have clear trichomes. As the buds approach harvest the trichomes become cloudy and eventually start to produce amber (or even red) colourations. Many harvest their buds as the trichomes are transitioning from clear to cloudy.

Related:
Understanding cannabis trichomes

What to do in case of early or late flowering?

If your plant flowers early you can look forward to an earlier harvest. A late flowering plant will generally have enjoyed more time for veg growth, so you may be able to look forward to a heavier harvest.

When growing autoflower seeds you may find some plants will be ready to harvest a week or two before the slower phenotypes. Remember each plant is different. Try to time the harvest so that you have buds of the perfect maturity level for your personal tastes. Some growers love the lively energetic buzz from an early harvested plant. Other growers will always wait an extra couple of weeks to ensure that their plants have a high proportion of amber trichomes which can produce heavier effects.

What really matters to the home grower is that they:

• are growing the best cannabis seeds for them personal needs and,

• they select the optimised harvest date which provides maximum enjoyment and satisfaction for their recreational or medical needs.

Other important cannabis life cycle considerations

There are different cannabis growth stages as well as different cannabis flowering stages. The experienced grower understands the various environmental, nutrient and lighting requirements at the various stages of cannabis growth.

What stage of growth does cannabis produce trichomes?

This can depend on the specific cannabis seeds being grown. Trichomes can be seen even on young plants though they can be microscopically small. As the plant matures the amount of trichomes increases dramatically. When growing photoperiod feminised cannabis seeds you may see the first trichomes around 3 weeks into bloom. Over the following month trichome production is heavy and gives the plant a frosty appearance, as if sprinkled with sugar.

When growing autoflower seeds, trichome production tends to start around 4 weeks after germination. In the following weeks, trichome production steps up a gear as the buds gain weight. Aroma also increases as more and more trichomes are produced.

What stage of growth does cannabis stop growing?

During flowering, most photoperiod cannabis plants stop stretching after around 4-5 weeks. After that point most of the growth happens on the buds. For autoflower plants, stretch tends to stop around 6-7 weeks after germination. At that point the bulk of the plants energy is focussed on bud growth and resin production.

But it’s worth adding that these figures are only approximate. Much depends on the specific cannabis genetics that you are growing, your environmental conditions and the grow method.

How long should the harvested buds be left to dry?

Harvested buds are typically left for 7-14 days to dry before being transferred to the curing jars. When the branches ‘snap’ (rather than bend) it’s an indication that the plant is dry enough for curing to begin.

How long should the harvested buds be cured?

Many would say that a month or two is a realistic minimum to allow the taste and aromas to fully develop. Keeping your cured buds in jars even longer isn’t an issue. Many people feel that a 6-month cure with your jars in cool/dark conditions is a great way to maximise taste and aroma.

How to keep a consistent cannabis growth timeline?

When growing photoperiod feminised cannabis seeds the growth timeline is up to you. You can offer minimal veg growth for a SOG grow or several months for a SCROG grow.

Autoflower seeds, on the other hand, have a cannabis growth timeline of their own. They, not you, decide when to start blooming. Good quality auto seed suppliers should be able to give you a good idea whether they are likely to have a growth lifecycle as fast as 9 weeks e.g. Auto Blueberry seeds or a slow growth lifecycle of 12-15 weeks e.g. Auto Ultimate seeds. Note that the autos which take longer to grow may well deliver very heavy yields.

Outdoor cannabis growers should note that the different regions you live in can also determine how many daylight hours per day you will have. That will have a huge influence on your outdoor cannabis lifecycle (or growth stages). Equatorial cannabis growers have 12/12 light (or thereabouts) almost all year round. This means you won’t have any veg time at all if you grow outdoors.

Understanding the cannabis growth stages is key

With an increased understanding of the different cannabis growth stages you will find your control and enjoyment of cannabis cultivation will increase. As well as optimising your grow environment and improving your understanding of the cannabis grow cycle be sure to select the best cannabis seeds for your personal grow situation. The choice of cannabis seeds may seem large and possibly confusing.

If so please check out the Dutch Passion Seed Finder which asks a few simple questions before recommending the seeds which best fit your needs.

As marijuana is legalized in more places, here’s how to grow your own

When it comes to growing his own marijuana, Chris Haynie leaves little to chance.

Inside a grow room in Richmond, Haynie has erected a 42-square-foot tent that houses four marijuana plants, the state’s legal limit for personal cultivation. Haynie’s setup is high-tech: An irrigation system releases moisture on a precise schedule; a motorized LED light timed to mimic the rising and setting of the sun moves along a rail across the top of the tent; and a monitoring system tracks key metrics of plant health, such as the moisture level and pH of the soil, and relays the data to an app on Haynie’s phone. If the system senses urgent problems, he’ll receive a warning text. Haynie’s friends are used to him bolting from a room mid-conversation to tend to his plants.

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Haynie, a bearded 38-year-old cannabis connoisseur who tattooed his thumbs with green ink, is no horticulture amateur. As the co-founder of Richmond’s Happy Trees Agricultural Supply, he’s part of a growing number of experts who are making a business out of teaching people how to grow their own pot. Recent laws in Virginia allow for limited cultivation of marijuana for personal use, and Happy Trees, which Haynie launched in 2019 with Josiah Ickes, 36, specializes in setting up growers to cultivate the plant.

Marijuana remains illegal on a federal level, but many states have abolished restrictions, creating a patchwork of rules throughout the country. Eighteen states and the District of Columbia have passed laws allowing recreational use. Virginia legalized home cultivation in July 2021; under the law, people 21 and older may possess up to an ounce of marijuana. It remains illegal, though, to buy or sell it in any form — including seeds — until 2024, when retail sales are expected to begin.

People still find ways to access seeds. When D.C. legalized the possession of limited amounts of marijuana in 2015, the District lacked the authority to create a legal economic market for sales. So cannabis activists organized seed giveaways throughout the city. At one early event in 2015, lines stretched for blocks.

The regulatory scheme also established what has become an expansive “giveaway market,” in which Washingtonians have used a loophole to provide harvested marijuana as a gift in exchange for the purchase of a legal product. Companies sell cookies, tea or paintings with a baggie of “free” marijuana on the side. One company sells motivational speeches delivered by a person who travels by bicycle.

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Growing cannabis in a greenhouse

The recent explosion in ‘growing your own’ cannabis includes the rapidly growing community of greenhouse growers. For many people, growing cannabis seeds in a greenhouse is simpler than creating an indoor grow room. Greenhouse growers find it easier than growing cannabis seeds outdoors.

Greenhouses offer protection from the elements, insect predators and grazing animals. Greenhouses also provide a longer growing season. You can plant your cannabis seeds a little earlier than if you were growing outdoors. The greenhouse also protects your plants form the worst of the autumn weather during harvest, allowing you a greater chance of a safe harvest.

The many benefits of growing cannabis seeds in a greenhouse allows growers in northern European regions the ability to grow high quality cannabis with either feminised seeds or autoflower seeds.

Cannabis seeds and greenhouses

Greenhouses can be heated if required. This allows you to optimise the greenhouse environment even if you have unexpected frosts or stormy weather. It also allows you to germinate your cannabis seeds earlier than you might do for an outdoor grow. Read all about how to germinate your seeds in our germination guide.

With a little bit of thought and planning, growing cannabis seeds in a greenhouse can be a safe, secure and pleasurable way for the home-grower to be self sufficient in recreational or medical cannabis. Greenhouse-grown cannabis is incredibly potent when grown from good cannabis seeds. It’s no surprise that more people than ever are growing in greenhouses and enjoying the benefits.

Autoflower seeds in greenhouses

Many greenhouse growers enjoy large harvests of over 100g (dried buds) from each autoflower plant. The protective environment of a greenhouse protects the autoflower plants from the worst of the weather and the extreme low temperatures which can occur especially in early spring and autumn.

Autoflower seeds usually grow from seed to harvest in around 100 days in a greenhouse. Compared to feminized cannabis seeds that is a short life cycle. The short life cycle of an autoflower means it is extra important to optimise growing conditions and environment in order to maximise harvest quality and quantity.

A greenhouse protects your plants from high winds, damaging rain and low temperatures. Insects and pests can be easier to deal with in a greenhouse and less of a nuisance. All these factors are reasons why greenhouses are a great asset for the cannabis grower.

Feminised cannabis seeds and greenhouses

Feminized seed varieties grow very well in greenhouses. Often, they will grow vegatively until they sense the shortening days, and will start to show first signs of bloom around August, depending on your variety. In the northern hemisphere feminized seeds are often grown from around April to October in a greenhouse.

In a heated greenhouse the seeds can be germinated and planted around March/April, depending on your local weather conditions. This allows an earlier start than is usually possible outdoors. That’s because the greenhouse offers extra protection from the worst of the early season weather.

As a result, a greenhouse allows you to grow larger plants which can start earlier and finish later than would be possible growing outdoors without a greenhouse. Many growers of photoperiod feminized seeds routinely harvest several hundred grams, or more, of dried buds from a single plant. Plants can easily reach 2-3 metres tall and just as wide. A greenhouse also protects your plants from the autumn/winter storms. This can allow the greenhouse grower to grow a broader range of later blooming cannabis seeds than is possible outdoors.

Greenhouse cultivation of cannabis seeds. Using pots vs planting directly into the ground

Greenhouse growers are split into two main groups; those that grow their cannabis plants in plant pots and those that grow them directly in the ground. Plant pots can be easily moved if they need to be, for example if visitors, extreme weather or other problems are present. But plant pots will need more frequent watering and occasional feeds. A large cannabis plant in a 10 litre container will need watering daily during very hot weather. That could be a problem if you are away and unable to visit your plants.

On the other hand you may experience less issues with humidity, especially if your greenhouse floor is covered with paving slabs. Growing in containers also allows the grower more control over nutrient addition.

Some greenhouse growers even feed their greenhouse cannabis with automatic systems (e.g. AutoPot, Blumat, dripper systems or similar). It’s possible to grow cannabis in soil, coco fibre or any other grow medium in a greenhouse.

Plants that are rooted directly in the ground obviously can’t be moved, but will survive well even when you are away for a week or two. There is less need to worry about daily watering. If your greenhouse contains good quality moist soil then your cannabis plants will establish an extensive root network which will support a large plant with heavy yield potential. However, if the ground under the greenhouse contains poor quality soil then remove it and replace with good quality soil before growing plants in it. Serious greenhouse growers will dig in plenty of manure and compost at the end of each growing season to ensure optimized soil quality for the following years crop. One advantage of rooting your plant directly into the ground is that you can grow very large plants with unrestricted root space. It’s one way to get XXL harvests. Some greenhouse growers, when using the best cannabis seeds, find that a single plant can occupy the entire greenhouse and occasionally even run out of space. If this happens you can try low stress training to tie down the taller branches. In extreme situations, some growers have even had to remove some roof panels from their greenhouse if the plant grows uncontrollably. Plants which are rooted directly into the ground can be grown using automated feeding systems such as dripper systems etc.

Greenhouse overheating. Protecting your plants from extreme summer heat

One problem with greenhouse growing is that the temperatures can get very hot in sunny mid-summer weather. High temperatures make it difficult for the plant to grow. Leaves may wilt and the roots can find it difficult to provide sufficient water. This can be a serious problem, especially in a heatwave when temperatures inside the greenhouse can be in excess of 30ºC or even 40ºC. At these temperatures the cannabis plant struggles since conditions are so far from optimum. But the determined greenhouse grower can find ways around these challenges.

Greenhouses can be fitted with windows which open in hot weather and close automatically when it cools down again. These allow the hot air to escape quickly. An open door in your greenhouse can allow a cooling breeze to flow through. Greenhouse doors made with panels of fine wire mesh keep insects out but allow air to flow through.

Sophisticated greenhouse growers have watering systems in place to simplify and even automate water delivery. If the greenhouse is not in an entirely private location then it might benefit from a coat of white shading paint. This is sold in garden centres and used to protect greenhouses from overheating on the hottest summer days. For the cannabis grower this shading paint also stops people seeing what is inside your greenhouse, but green plastic plant mesh and tomato plants have also provided excellent cover for many generations of greenhouse growers.

Anyone that has been in a greenhouse on an early spring day will note how quickly they warm up in sunshine. This allows growers to get their preferred cannabis seed varieties started earlier in the season than they could outdoors. This allows the growing season in a greenhouse to start earlier. Your greenhouse will therefore benefit from larger plants and subsequently superior harvests. Cold nights can be mitigated with the use of greenhouse heaters that are available to purchase at any garden centre.

Just as with outdoor grown cannabis, the shift towards shorter days during the summer is a signal to the cannabis plant to start flowering and produce the desired female buds.

How do I get rid of excessive greenhouse humidity?

If you have ever seen your greenhouse windows dripping with condensation then you need to give some attention to reducing greenhouse humidity. Excess humidity creates an unhealthy growing environment for your plants and can encourage bud rot and mildew. Wet greenhouse glass panels will soak any leaves, branches or buds that press against the glass. If you want to ensure optimized plant health then consider some ways to make sure humidity doesn’t damage your plants.

Ensuring air movement and regular air changes in your greenhouse is important. Some of the techniques used to keep your greenhouse cool will also reduce humidity. Having adjustable roof vents which can open to release humid air is a great help. Having a through-draft thanks to an open greenhouse door is also a good idea.

Many greenhouse cannabis growers have fans in their greenhouse to move air around, and even to push air out of a door or open roof vent. This may mean fitting an outdoor, weather proof electricity connection to your greenhouse. But its a small price to pay for improved cannabis quality. A fan will also strengthen the stems of your cannabis plant by mimicking the effects of an outdoor breeze.

Some people copy the large legal greenhouse growers in the USA and fit an extraction fan to pump humid stale air out of the greenhouse. This can be combined with a carbon filter to remove any cannabis aroma from the exhausted air.

How large do cannabis plants get inside a greenhouse?

If the greenhouse grower can get good soil for his plants and (most importantly of all) start with good cannabis seed genetics then the plants can grow into true monsters by the end of the grow season. The greenhouse grower can see cannabis plants reach sizes rarely seen indoors. Many greenhouse growers have grown single plants that have filled small greenhouses and produced several hundred grams of top quality weed per plant. Good quality cannabis seeds may cost more but they deliver far superior results in the long run.

As previously mentioned, some greenhouses have windows that can be opened to let any monster plants grow out. But a safer option is to use cord to try to ‘tie down’ the plants if they do start growing massively. The photos above show what can happen when a prolific strain starts to turn into a large bush that wants to grow as high as a small tree. The plant simply becomes too tall for the greenhouse. The soil conditions, temperatures and good care resulted in a plant that was thriving as if in the jungle rather than a garden in northern Europe.

Of course this type of extravagant growth rarely occurs when cheap cannabis seeds are grown in poor quality conditions with badly prepared soil. Growing a monster plant requires properly dug, well prepared nutritious soil at the start of the season. The pictures show large cannabis plants simply outgrowing the greenhouse, delivering heavy harvests for the grower. The Dutch Passion Shaman variety was bred specifically for outdoor/greenhouse conditions. Shaman combines some incredibly potent skunk/purple skunk parents with vigorous growth. Shaman eventually grew into a bush 3 metres tall and two meters wide, winning the Dutch Passion photo contest award in 2006. In this case the grower was forced to remove a pane of glass from the greenhouse as his resin soaked Shaman outgrew the tall greenhouse. The plant was too strong to be tied down, and security was not a problem on this particular grow so the grower went on to harvest an abundance of top quality greenhouse grown cannabis, despite the obvious size problems of the Shaman.

Cannabis genetics and greenhouse growing

When growing with good cannabis seeds in a greenhouse remember that some plants will grow as wide as they are tall especially if they have plenty of sun, good soil and ample root space. Remember too that a few seeds could provide a years worth of medication or recreational weed, so regard the cannabis seed as an investment and get a good variety. Cannabis seeds are one area of your life where you really don’t need to compromise. Look at the Dutch Passion website for some cannabis cup winning options. Proven varieties for greenhouse growing, especially at northern latitudes, includes Shaman, Durban Poison, Passion #1, Frisian Dew and Frisian Duck. These varieties have been used by numerous repeat growers over many years. They have passed stringent standards for potency, quality, pest/mold resistance and vigour. Growing these feminized seeds in a greenhouse will deliver excellent results.

Early flowering using a ‘darkening system or extending your growing season

Some growers equip their greenhouses with a ‘darkening’ system. Essentially this involves using dark blinds/curtains to create blackout conditions inside even when it is sunny outside. This can be used to simulate short summer days and ‘force’ the plants to start flowering and producing buds much sooner than normal. Although this involves extra expense it is one way of accelerating greenhouse weed production. The grower simply uses the blinds to reduce daily light exposure to 12 hours (or less) and the plants in the greenhouse respond by flowering.

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Greenhouses also have the benefit of allowing the grower to extend the end of the growing season. Cold sunny autumn days on the outside become warm and comfortable in a greenhouse and allow plants to ripen properly. Pests are normally easy to control in a greenhouse, and so long as the greenhouse is secure it is a great and simple way of growing.

Many also grow cannabis seeds in polytunnels these days, the benefits of the poly tunnels being much the same as greenhouses. Polytunnels protect against the worst of the elements, keeping the plants safe and giving a long growing season. Polytunnels come in a wide range of sizes and they also offer privacy to the grower.

Greenhouse growing of cannabis has lower ongoing costs compared to indoor growing, where large amounts of cash are spent on grow lights and ongoing electricity use. By contrast, growing cannabis in a greenhouse only requires a seed and some substrate to grow in. The sun provides free energy for your plants to grow.

Greenhouse grown cannabis versus outdoor cannabis

Many outdoor cannabis growers eventually upgrade to greenhouse growing. The greenhouse allows more potent crops, higher THC levels and a better terpene profile due to the protection offered by a greenhouse. Whether you are growing with a large commercial budget, or a small greenhouse with just one or two plants, the quality improvements are always important and appreciated. Because greenhouse grown cannabis plants grow in a more sheltered environment the plants are healthier, enjoying more optimized conditions. The plants can grow without damage from extreme cold, storm/hail damage and wind damage. Pests and disease are easy to prevent and deal with in a greenhouse. A greenhouse protects your plants from the worst of the weather, hail and torrential rain. Greenhouses protect your plants from cold weather, creating a warmer environment where your buds can ripen and mature under conditions which are often far superior to outdoor weather.

Growing cannabis seeds in a greenhouse with artificial lighting

Even in warm climates, many greenhouse growers supplement the natural light with additional light on cloudy days. These days LED grow lights can be used to provide additional illumination which can be automatically switched on when ambient daylight (PPFD) levels drop too low. Growers in cool climates, such as Scandinavia may prefer to use supplemental HPS lighting which offers both light and heat to the plants. Supplemental lights also allow you to extend the natural sunlight hours. This would allow you to grow autoflower seeds in a greenhouse and have 18-20 hours of daily light. Artificial light would be used to give the autoflower plants their preferred 20 hours of daily light with optimized yields and quality.

The experienced grower can use the benefits of a greenhouse to grow larger plants, with improved quality and a longer life cycle. Plants can be started earlier and harvested later thanks to the extra protection offered by the greenhouse. During the cultivation process the conditions inside a greenhouse are better than those outside, promoting improved plant health, superior yields and better potency. Outdoor grown plants, without these benefits, usually offer lower yields and quality.

Where to locate your greenhouse?

If you get a greenhouse it pays to think carefully about the location. When it comes to security, always think about a location which makes it difficult for neighbours or the public to see/smell your crop. Also consider your local climate. If you are living in a cool climate it pays to locate the greenhouse where it will receive maximum sunlight for as much of the day as possible. If you live in a hot, desert climate you may want to consider locating the greenhouse under some trees which will shade the greenhouse during the hottest hours of the day in mid-summer. Mediterranean greenhouse growers may wish to place their greenhouse in a cooler, northern part of the garden where some shade may be present. Remember that when temperatures reach 40-45ºC the temperatures become damaging.

Many greenhouse growers also arrange a hosepipe/water connection near their greenhouse. This simplifies the process of getting water to your plants. The last thing you need on a hot day is numerous long walks from your house to the greenhouse with a watering can.

Greenhouse options for cannabis growers

Greenhouses are available in a wide range of sizes and budgets. The lowest cost ones use a flexible transparent plastic mesh sheet which fits over a small plastic/metal pole frame. These can cost as little as €20 but can only fit a single plant inside. Some greenhouses are designed to be leant against an outside wall of the house. Heat from the house helps keep the greenhouse warm. Greenhouses are also available for people that live in an apartment and have a small balcony. Polycarbonate greenhouses use toughened ‘unbreakable’ transparent plastic panels instead of glass, these are useful if you are worried about safety or have small children. Whatever your budget and space, somewhere there is a greenhouse for you.

Growing cannabis in a greenhouse. Easy and effective cannabis growing

Growing cannabis in a greenhouse is a simple and cost effective way to be self sufficient in your cannabis needs. Greenhouse growing seems to be a rapidly expanding pastime amongst cannabis growers of all backgrounds in a wide range of countries.

The more professional greenhouse grower will take care to introduce new, good quality soil/fertilizer each year and keep the greenhouse clean and tidy to minimise potential for pests and disease. Some greenhouse growers use strategically placed fencing and shrubs to make the greenhouse inaccessible to unwanted visitors and invisible to prying eyes. Greenhouses are cheap to buy. You can buy small low cost plastic ones for not much more than a hundred euros. Even cheaper ones are available with plastic covers. They are available everywhere and come in any shape/size required for all budgets. Some of the modern polycarbonate greenhouses are also opaque giving instant privacy and have lockable doors. What more could you need in your back garden? Remember that poor quality cannabis seeds can’t produce connoisseur quality cannabis, no matter how well you grow them. Invest in the best cannabis seeds you can get from a company with a proven reputation, and enjoying growing your own cannabis in a greenhouse.

30 Comments . Leave new

Thanks for the wisdom Dutch Passion, trying to prevail over the bad weather now in UK with some of your Frisian Dew. Closed up my greenhouse letting a good air supply breeze through some openings and one hole at the top for rain water to drip down. Wish me luck !

We always hope for one of those late summer periods during the end of flowering, but we’re not always that lucky.
But Frisian Dew should be able to handle some harsh conditions. So we hope you still end up with some great results! Good luck!

Nice info!! I clear my doubt here. Keep sharing such info with guys. And also get more information about cannabis here, https://420expertadviser.com/grow-lights/mars-hydro-600w-review/

Hi there Dutch passion, what is the best feed to put into your plant? Cherrs

We advice biotabs for your plants, super easy organic nutrients which will make your babies happy!

Hi, for a reason I have to move my indoor Plants almost 2 weeks at the end of the flowering period (12h ) outside where they get 11 hours direct sunlight..is it safe? are they gonna go back on vegetative grow again?
Thanks for your advice

This will surely bring some stress to your plants. When you move them outside do they get more than 12 hours of sunlight (not direct but in total)?

Because if they go to an environment where they will have longer days they will go in to vegetative state again and you do not want this if your plant is finishing up flowering.

Greetings,
Joe
Dutch Passion

I am new at this. My plant has reached the top of my outdoor greenhouse. It is still in veg. stage Would it stress the plant if I remove the greenhouse? I has two doors that are open, so the plant has been getting a lot of direct sunlight.

Hey,
If the temperatures are not too low outside without a greenhouse this should be no problem and should not give a lot of stress to your plant.

Hi.
How many plants autoflowering per square
meter I can put in greenhouse ?

We advice around 4 autoflowers per square meters so they have enough room to grow big

Greetings,
Dutch Joe

help ! I am at week 12 of auto flowers in a GH – but I think the grow has stalled ? super early signs of buds for the last 3 weeks but then nothing ? Started in June. Super bushy and good looking but no bud growth ? Any ideas ? should I start with some bloom nutes ?

After 12 weeks you should definately have some bud production. If you want you can send us over some pictures so we can assist you better. Please send them to [email protected] with some information about your grow.

Greetings,
Joe
Dutch Passion

My plants are pushed up against the glass after two prunes will this effect the plants when they flower?

If the buds are against the glass you have a high chance of bud rot because there is not enough air flow through the buds.

Greetings,
Joe
Dutch Passion

Will my plants still ripen in a opaque green house. Do I need a light in there. They are about 2 weeks from Harvest. But, we are getting down to 12 to 22 degrees Fahrenheit at night

If you could give them some supplemental lighting that would be great. Your plants will have a hard time with these temperatures and with some extra light you can make it a successful harvest

Greetings,
Joe
Dutch Passion

Is it possible to grow cannibis in a green house using a tinted plastic material or polycarbonate that isn’t crystal clear?

It should be possible, but sunlight is very important for your plants. Sufficient light penetration should be possible with your plastic material. Do you know if other plants grow under this material?

Greetings,
Joe
Dutch Passion

I have just received my californian orange seeds thankyou for your fast delivery I have ordered a plastic greenhouse and will be using pots do I germinate them inside my house first ? My garden gets very hot with sun from 9am to 7pm in summer

It is indeed best to germinate them in your house because there the seeds will have a stable environment and temperature.

In the first stage after the seedlings germinate you should be careful with direct sunlight because it can damage them.

Greetings,
Joe
Dutch Passion

Hello, i have Auto Think Different in greenhouse in pot, but i dont know if direct sunlight avaible if better to stay in greenhouse or take pot to direct sunlight as much possible sometimes we have there also 30C, what do you think?Im from Czech Republic.thx for answer and sorry for bad english.

If your pots are mobile, I advice you to move them out of the Greenhouse and in to the sunlight when you have extremely hot temperatures.
If the temperature is around 20/25 degrees Celsius you can leave them in your greenhouse as long as you ventilate enough

Greetings,
Joe
Dutch Passion

Hello friends I live in a country where the use of marijuana is against the law. I intend to plant a greenhouse. Thank you for teaching me zero to one hundred planting jobs.

I have started plants in a tent 18/6 lighting in Feb have taken out of Tent and put on dressing table before putting them in greenhouse, will they survive?

To give a good answer we would need some extra information like the conditions that you have for your plant on the dressing table. Could you please send us an email at [email protected] with some explanation and perhaps some pictures? Than we can help you from there.

Greetings,
Joe
Dutch Passion

At what stage should plants be moved during the day time from window sill to either greenhouse or garden? (In southern England where it is pretty warm now). I have the option of both garden or greenhouse

Around 2 weeks after your seedlings have come out of the ground you can put them outside. Be careful in the beginning with too much direct sunlight, the seedlings cannot handle too much in the beginning. At the very start you can also take them inside at nighttime to protect them even more.

Greetings,
Joe
Dutch Passion

Should I use shade cloth over my greenhouse in the hot summer days?

Ventilation is really important in a hot greenhouse, if it really gets too hot you can use a shade cloth as well

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