Growing melons in the home garden
For best performance, plant melons in hot, sunny locations with fertile, well drained soils.
Plant melon seeds 1 week to 10 days before the last spring frost date.
Watermelon and honeydew are more cold-sensitive than cantaloupe.
Melons will not all ripen at the same time, so plan to pick them as they become ready.
Challenges to growing melons in Minnesota
It is a challenge to grow melons in Minnesota. Melons demand special care but reward gardeners with juicy, sweet fruit.
Most winters our soils freeze deeply and can be slow to warm up, and melons must have truly warm soil to thrive. Once summer comes, our long, bright, hot days are good for developing the vines, flowers and fruits.
Melon quality—flavor, aroma, texture, and sweetness—is best when the sugar content of the fruit is high. Sweet melons need lots of sunlight, warm temperatures, enough water, and freedom from diseases and insects.
Plant stress, whether from insects, leaf diseases, weeds, poor nutrition, too much or too little water, or cold or cloudy conditions, will prevent the fruits from creating enough sugar.
Preparing to plant melons
Soil and fertility
to determine pH.
- Melons grow best on well-drained, sandy loam soils, with a pH between 6.0 and 6.5.
- Soils with a pH less than 6.0 will produce plants with yellow foliage that set few or no fruit.
- You can improve your soil by adding well-rotted manure or compost in spring or fall. Do not use fresh manure as it may contain harmful bacteria and may increase weed problems.
- Build raised beds to ensure adequate drainage, which these crops require.
Selecting melon varieties to plant
Cantaloupe and muskmelon have netted skin, a strong aroma and moist fruit that is usually orange, but may also be green.
Honeydew melons are smooth-skinned, with pale flesh that may be white, green, or orange. Both types are the species Cucumis melo. Watermelon is Citrullus lanatus.
- Only varieties with short growth cycles of less than 90 days to maturity can produce a ripe fruit in the north, and the first ripe fruit might be the last.
- Choose varieties with fewer days to harvest (65 to 80) to increase the chances of harvesting more fruit that has ripened under warm conditions.
- Even in the southern part of the state, and in the Twin Cities heat island, varieties with fewer days to maturity are more likely to provide a satisfying harvest.
Pollination and flower types
- Cantaloupe and honeydew vines produce two flower types: male flowers and perfect flowers (having both male and female parts).
- Slender stems attach male flowers to the vine.
- A short, thick ovary, which will become the fruit, attaches female and perfect flowers close to the vine.
- Pollen needs to transfer from the male flower to the female flower on this day for seed set and fruit development.
- The number of seeds set helps determine fruit size and shape.
- Poorly pollinated flowers either fail or produce misshapen fruit.
How to extend the growing season before planting
Using season extension techniques such as soil-warming mulches, hot caps and low tunnel row covers, gardeners can get the soil to heat up sooner and protect melons in late summer if there is an early frost.
For both direct-seeded and transplanted melon plants, these techniques and materials can allow planting two or three weeks earlier.
- Plastic mulch
- warms the soil
- conserves water
- helps to control weeds
- allows earlier planting and maturity
- reduces ground rot of the fruit
- Under the cover, daytime and nighttime temperatures are higher than outside the tunnel.
- The tunnel also protects the plants from wind and flying insects.
- Remove covers once fear of frost has passed to avoid injury from too much heat, and to allow bees and other pollinators access to the flowers.
- You can direct seed or transplant melons into the garden between mid-May in southern Minnesota and late June in northern Minnesota.
- In the northern part of the state, melons planted in late June must be ready for harvest before mid-September, when frost is likely.
- Melons perform best in hot, sunny locations with fertile, well-drained soils.
Plant melon seeds 1 week to 10 days before the average last spring frost date, it is important to wait until the soil is warm enough.
- Use a thermometer to take the temperature of the top two inches of soil.
- Melon seed germination is best between 70°F and 90°F.
- Plant only after the soil temperature has reached 65°F, when nights as well as days are warm.
- Planting in cooler soil can lead to soil-borne root diseases, which can stunt or kill melon plants, and the plants will grow slowly even if they do not show signs of disease.
- In the southern half of Minnesota, most soils are not usually warm enough to plant melons until after May 20.
- In the northern half of the state, the soil may not reach this temperature until sometime in mid-June.
Prepare the soil for the melon planting about 2 weeks before the average last spring frost date in your area.
- Use compost and fertilizer.
- Form six to eight inch high raised beds to speed soil warming and have good drainage.
- Plant the seeds ½ to one inch deep.
- Sow 2 or 3 seeds in groups 18 to 24 inches apart.
- Space rows 5 to 6 feet apart.
- After the seedlings emerge, choose the strongest plant in each group and remove the others.
Transplanting can add two to four weeks to the growing season, but melons are especially sensitive to root disturbance. In the case of a broken or damaged root, the plant may never recover, or it may grow slowly all season, leading to a disappointing harvest.
Start melon seeds indoors before transplanting to your garden outside.
- Sow seed indoors at the end of April, about 2 to 4 weeks before the last spring frost date.
- Use peat pots or other biodegradable containers that you can place directly into garden soils.
- Use larger pots than you would for other vegetables.
- Large peat pots with a diameter of 4 inches will allow the root system to develop.
You can grow small-fruited melon plants in small gardens by training the plant to a fence or trellis.
After the fruits begin to enlarge, they will need support, or the fruit weight may damage the vines.
You can make slings to hold up the fruit using wide strips of fabric tied to the trellis, with the melon fruit resting its weight on the fabric.
Variety Information: 7″ x 8″, 7–8 pounds, light green, and very sweet and juicy.
When to Sow Outside: RECOMMENDED. 1 to 2 weeks after your average last frost date, and when soil temperature is 70°–90°F.
When to Start Inside: Recommended for short-season areas. 2 to 4 weeks before transplanting within 2 weeks after your average last frost date. Sow into biodegradable pots that can be directly planted in the ground; roots are sensitive to disturbance.
Days to Emerge: 5–10 days
Seed Depth: ¼”
Seed Spacing: 2–3 seeds per mound
Row Spacing: 4’–6′ apart
Thinning: Thin to 1 plant per mound
Harvesting: Harvesting at the right time is very important with melons. Commercial growers harvest before melons are ripe, forcing them to ripen off the vine, but the last few days of ripening on the vine put a lot of sugars into the melon; so melons taste significantly better when vine ripened. How do you know when ‘Sweet Delight’ melons are ripe? A ripe melon will have a pleasant, fruity aroma at the blossom end; and a crack will form on the stem right near the point of attachment (this is called the “slip stage”). In a few days, the melon will detach from the vine with little effort and pressure. If it is somewhat difficult to detach the fruit from the vine, the melon is not ready yet. Do not allow to over-ripen.