Could you please tell me when to start heirloom watermelon seeds for outside planting right after the Derby? I have several varieties with no specific instructions on any of them.
The Gardener’s Answer
Hello, Larry: Watermelon is a wonderful treat in the summer time, especially if it is homegrown! This warm-season crop will be damaged by frost so we must plant outdoors after the frost-free date has passed. The average frost-free date for our area is May 10. Planting after this date will allow enough time for the soil temperature to rise. There are many different heirloom varieties, and each will differ in size, flavor, shape, and maturity time. Depending on variety these melons will mature anywhere from 70-100 days. Watermelon is a vine that requires a lot of space to grow. Keep this in mind when preparing the space for planting. It is best to sow the seeds in raised planting rows/hills that are 6-8 feet apart. The seeds should be planted 1 inch deep and 6-12 inches apart. They may need to be thinned after you determine the best plants. Watermelon (Citrullus lanatus) are sun lovers so they will need to be planted where they will receive at least six hours of direct sunlight each day. They are also heavy feeders so it will benefit the plants to add compost to the soil before planting. If you want to get a head start you can start your seeds indoors two to three weeks before the frost-free date. They will need to stay around 80-85 degrees F indoors so you may need a heating mat to place under the containers. Make sure to keep the soil evenly moist and then you can transplant them outdoors after May 10. For now make sure your seeds are stored in a cool, dark, dry space.