Transplanting a Watermelon Into Soil

Starting Seeds

• Watermelons are large-seeded plants that grow rapidly, so choose a container that is 2 to 3 inches wide. Fill the pot with moist seed-starting soil, place one watermelon seed on top and cover the seed with about 1 inch of soil. Watermelon seeds prefer warm temperatures for germination, so maintain the pot at about 85 degrees Fahrenheit. After the watermelon sprout emerges, move the plants to a more moderate temperature of about 75 F.

Growing Transplants

• Your watermelon starts will remain in their pots for two to five weeks. In general, a larger pot allows you to wait longer before transplanting, but the benefits of transplanting may start to decline after about three weeks because pot-bound watermelons will be slow to resume growth after transplanting. Watermelons thrive in hot weather, but you should maintain moderate temperatures for your seedlings so they do not suffer excessive shock if chilly, wet weather moves in after transplanting.

When to Transplant

• Consider both seedling size and weather conditions when you are determining when to transplant. Watermelons are extremely sensitive to frost, so wait until all risk of frost has passed. Also, avoid transplanting into soil temperatures below 60 F. Watermelons cannot effectively absorb water from cold soil, and the plants might wilt and die before they become established. If weather conditions are appropriate, it is best to transplant watermelons when the second true leaf is starting to grow.

Transplanting

• Watermelons, like other cucurbits, have fragile root systems that are highly sensitive to the stress of transplanting. Regardless of the transplanting system you use, it is essential to minimize disturbance to the roots. Turn the pot upside down and gently tap out the plant so that as much soil as possible remains attached to the root ball. Carefully bury the root ball, and part of the stem if the stem is long, in well-prepared garden soil, then water lightly to settle the soil around the roots.