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cannabis seeds haven’t sprouted

Seeds aren’t sprouting.
March 24, 2010 4:53 AM Subscribe

Last year, I started seeds in normal potting soil and they shot up within a week. This year, I bought a bag of "seed starter" soil and I was required to move the location of the seeds from last year (to protect them from the new cats). Other than that, everything else is the same – same trays, misting the cups every day with water.

Nothing has sprouted, and I’m beginning to worry. They were a mix of new seeds purchased at the same time as the soil and seeds from last year. I know the seeds from last year are still viable because I planted some in a large pot of last year’s soil and those have already sprouted.

Will it just take longer for the seeds in the starter soil to get going? I seem to remember something about potting soil maybe having too much nitrogen(?) for seeds, causing them to grow too fast – could that be the explanation? Maybe they’re too cold? I had the tray of seeds in a window last year.

The seeds are all typical garden vegetables – a couple types of tomatoes, peppers, and some herbs.

Best answer: Germination requires water and a suitable temperature, and that’s about all. Soil conditions may affect the developing plant, but the soil you have is highly unlikely to be the problem.

Just misting the soil may not be enough – it’s possible that you’re just wetting the soil above the seeds. Check that the soil is moist all the way through – if not, stand the pots in some water until it is. Other than that, keep everything warm and be patient.
posted by le morte de bea arthur at 5:11 AM on March 24, 2010

Rather than misting the seeds, keep the little pots in some sort of enclosure until they sprout. That’s what those plastic-domed ‘mini greenhouses’ are for — to keep the air around the pots moist. A plastic bag, or a piece of saran wrap, or a repurposed take-out food clamshell all work just as well. Whatever enclosure you use, put it in a warm spot. If the soil was moistened before you put it in the pots, misting should be unnecessary.

As soon as the seedlings sprout, remove the pots from the enclosure and put them under lights.
posted by jon1270 at 5:51 AM on March 24, 2010

1. moisten the soil
2. then fill the pots
3. then plant the seeds
4. sit pots in a tray of water for about 20 minutes so the soil takes up as much water as it wants
5. place pots in enclosure, in a warm spot, and check daily.
posted by jon1270 at 5:53 AM on March 24, 2010

It’s unlikely that you will need to soak the pots more than once, and keeping the soil really saturated will prevent germination by causing fungal diseases. I like to do an initial soak, then drain, and rely upon the dome or plastic wrap or whatever to keep moisture in. You can always mist if you think the top of the soil is drying out.

As other people have said, temperature is important. I would have thought a radiator would be too hot. In the past I’ve used heating pads and even an electric blanket for a large number of flats, aiming for about 80 deg F soil temperature.

I’ve also been really impatient, and trashed whole flats of seeds I was convinced were bad, only to look in the bucket of discarded soil mix and see those seeds (in the cold and dark, uncovered) beginning to germinate. If I had just waited one more week.
posted by werkzeuger at 6:56 AM on March 24, 2010

I had been keeping the tray on a radiator

Uh, you may have cooked the seeds. Operating radiators tend to be waaaaay too hot. Soil temp should be around 75F; not even bath water temperature. Try the top of the fridge.
posted by jon1270 at 6:58 AM on March 24, 2010

radiator may have cooked your seeds

Another possibility is that the radiator may have killed the seeds by drying them out. If a germinating seed goes really dry even for a little while, it’s dead.
posted by musofire at 8:08 AM on March 24, 2010

I love growing from seeds and am not half bad at it. This information is in other posts, so I am both nthing and collating.

I’d say 99% chance that it is the soil temp or moisture level. You don’t say that you have any kind of mini-greenhouse going on. You need a clear plastic bag around your tray to keep the moisture in. Even just one mini-dry out will kill the seeds attempting to sprout. Sad, but true.

The other possibility is the soil temp. If the seeds are by a window, then they may be chilly. It’s kind of a catch-22 since of course they need light, but not a ton to sprout. The plastic will help with soil temp regulation as well.

I don’t know what kind of trays you are using. I use whatever — dixie cups, yogurt containers, with a small square of plastic fixed to the top by a rubberband. Then you only have to adjust the water when tiny beads are not forming on the clear plastic.

posted by letahl at 9:43 AM on March 24, 2010

You’ve probably got more seeds in the relevant packet than you’ll ever need, so why not start another set and leave the old ones as they are in case they do sprout?

Be sure you moisten the soil mixture thoroughly before putting it into the containers. Some seed starting mixtures, especially those based on peat moss, can be really difficult to moisten the first time or remoisten once they’ve dried out.
posted by jon1270 at 1:21 PM on March 24, 2010

1st time grower – My seeds won't germinate

I am by no means an expert, I haven't even attempted to grow marijuana (I just like to lurk and dream), but I have grown flowers from seeds before. When you germinate, you really just need DAMP substrate. Not soaking. In fact, you could even use a dish towel. Wet it, ring it out, and fold the seed inside (keeping the towel damp) until it cracks. That's when you put it into your substrate. And I'm pretty sure whenever you water your plant, no matter the stage, it should never be completely soaking wet. Roots need oxygen.