Seedless Watermelon

A triploid watermelon hybrid that produces virtually seedless fruits with sweet, crisp red flesh. Seedless watermelons require a regular seeded watermelon planted nearby as a pollinator to set fruit, so always include both types. The seeds are often slower to germinate and more sensitive to cold, so start them indoors in warm conditions. Though called seedless, they may contain small, soft, white, edible seed coats that are far less intrusive than black seeds.

Start seedless watermelon seeds indoors 4-5 weeks before the last frost as they need warm, consistent conditions for reliable germination. Plant seeds pointed end up, 1 inch deep, at a constant 85°F. Temperature fluctuations cause seed coat cracking and poor germination. Use a heat mat and monitor closely. Do not overwater seeds which causes rot. Germination takes 7-14 days. Start pollinator variety seeds at the same time. Transplant after hardening off when soil is warm and nighttime temperatures stay above 60°F.

The Season Plate

Your Seedless Watermelon Year

Composed for Zone 7 · typical seasons · frost passes Apr 2, returns Nov 1

Sow Seedless Watermelon May – Jun, pick Aug – Sep. Set your climate below and every date on this plate re-times itself.

Sowing window

May – Jun

re-timed to your frost dates

Plant out

after Apr 2

once frost risk has passed

First picking

around Aug 13

≈ 90 days from sowing · 2-4 melons per plant

Composed for —ColdTemperateMildWarmUse my locationUsed once to set your season · only the zone is kept

Week-by-week Seedless Watermelon reminders watering, feeding and pruning, timed to your dates

In the app

Frost alerts for your garden a warning before a cold night costs you the crop

In the app

Succession sowing dates so the picking never gaps mid-season

In the app

Prefer email? Get monthly reminders in the Almanac

Keep my dates — free for 7 daysWe nudge you as each window opens · cancel anytime

Seedless watermelons are triploid hybrids that produce nearly seed-free fruits with sweet, crisp flesh. They require a pollinator variety (diploid) planted nearby because triploid plants produce sterile pollen. Plant one pollinator for every 2-3 seedless plants. Direct sow or transplant after frost danger passes and soil reaches 70°F. Space plants 4-6 feet apart.

Seedless watermelon seeds are more expensive and have lower germination rates than seeded types, making indoor starting more economical. Plant seeds pointed end up at 1 inch deep at a consistent 85°F; temperature fluctuations drastically reduce germination. These plants are otherwise grown identically to seeded watermelons, needing hot weather, consistent moisture during growth, and reduced watering near harvest.

Use black plastic mulch and row covers to maximize soil warmth. Water with 1-2 inches per week during active growth, delivered through drip irrigation to keep foliage dry. Reduce watering during the final 2 weeks before harvest to concentrate sugars. Each plant produces 2-4 melons weighing 12-20 pounds depending on variety. The pollinator variety produces seeded melons that are also edible, so nothing goes to waste.

Most importantly, seedless watermelons must be planted near a seeded pollinator variety for fruit production. Beyond this requirement, grow alongside corn for wind protection and beans for nitrogen fixation. Marigolds and nasturtiums deter pests and attract beneficial insects. Sunflowers bring pollinators essential for fruit set. Radishes may help deter cucumber beetles. Avoid planting near potatoes and other cucurbits that share disease problems. Provide ample space as vines spread 6-8 feet.

The Society Table

Corn belongs beside it. Potato doesn't.

Old growers' knowledge, checked against Seedless Watermelon's real companion table below — test any plant you're growing.

Grows well in the company of · 3

CornMarigoldRadish

Keep apart · 1

Potato

Plant Seedless Watermelon with good neighboursThe planner flags conflicts before they're in the ground

Related growing guides

Vegetables

Corn

A good companion for Seedless Watermelon

Flowers

Marigold

A good companion for Seedless Watermelon

Vegetables

Radish

A good companion for Seedless Watermelon

Vegetables

Cucumber

View growing guide

Seedless watermelons need warm, well-drained sandy loam with a pH of 6.0-6.8. Build raised hills enriched with compost and aged manure for best results. Apply balanced fertilizer at planting and switch to low-nitrogen, high-potassium feed when fruits set. Black plastic mulch is particularly important for seedless types as they need consistently warm soil. Avoid excessive nitrogen which produces vines at the expense of fruit sweetness. Sandy soils that warm quickly produce the sweetest melons.

Ideal Temperature

Hardiness Zone Compatibility

Harvest seedless watermelons using the same indicators as seeded types: the tendril nearest the fruit is brown and dry, the ground spot turns creamy yellow, the rind develops a dull finish, and tapping produces a deep hollow sound. Seedless varieties may be slightly harder to judge ripeness as they can split if left too long on the vine. Cut with a sharp knife leaving 2 inches of stem. Typically ready 85-95 days from transplanting. Ripe seedless melons have a satisfying crack when cut open.

Storage & Preservation

Whole seedless watermelons keep at room temperature for about one week or refrigerated for up to two weeks. Cut melon should be refrigerated and consumed within 5 days. Cube and freeze on trays for smoothies and frozen treats. The absence of hard seeds makes seedless watermelon particularly convenient for juicing and blending. Watermelon juice freezes well in ice cube trays or as popsicles. The rind can be pickled though seedless varieties tend to have thinner rinds than seeded types.

Troubleshooting Common Problems

Poor germination is the biggest challenge with seedless watermelon seeds due to their triploid nature. Maintain consistent 85°F soil temperature and plant pointed end up. Forgetting to include a pollinator variety means no fruit; always interplant one seeded variety for every 2-3 seedless plants. Mark pollinator plants with different-colored stakes to avoid confusion at harvest. Hollow heart can occur from rapid growth fluctuations. Fruit splitting is more common in seedless types; maintain consistent moisture.

Growing Tips

1. You must plant a seeded pollinator variety alongside your seedless watermelons — this is the single most important rule. Seedless varieties produce sterile pollen and cannot pollinate themselves or each other. Plant one pollinator for every two seedless plants within 5 meters.
2. Plant triploid seeds pointed-end up. The thicker seed coat of seedless varieties traps moisture around the embryo and causes rot if planted flat or pointed-end down. Planting at a shallow depth of 1 cm with the pointed end upward allows moisture to drain away and dramatically improves germination.
3. Germination requires higher soil temperatures than standard watermelons — 27-30°C (80-85°F) is the target range. Use a heat mat for indoor starts and do not direct-sow until soil is thoroughly warm. Even a few hours of cool soil temperatures can kill triploid seeds.
4. Black plastic mulch is almost essential for success in zones 7-8. It warms soil 3-5°C above ambient, suppresses weeds, conserves moisture, and keeps developing fruit clean. Cut X-shaped planting holes and tuck edges securely.
5. Water deeply and consistently during vine growth and early fruit development — 2.5-5 cm per week at the root zone. Then reduce watering as fruit approaches maturity to concentrate sugars. Excessive late-season watering produces bland, watery melons and can cause fruit cracking.
6. Identify female flowers by the small melon-shaped swelling at the base of the bloom. If you see female flowers but no fruit is setting, pollination is failing — check that your pollinator variety is blooming simultaneously and that bees are active. In cool or rainy weather, hand-pollinate by transferring pollen from seeded male flowers to seedless female flowers with a small brush.
7. Limit each vine to 2-4 developing melons by removing excess small fruit. This directs the plant's energy into fewer but larger, sweeter melons rather than many undersized, bland ones. Pinch off any new female flowers once your target number of fruit has set.
8. Learn the ripeness indicators and use all of them together: the tendril nearest the fruit stem turns brown and dry, the ground spot changes from white to creamy yellow, the rind shifts from glossy to slightly matte, and a knuckle thump produces a deep hollow sound rather than a sharp metallic ping.