For many, the sweet and fresh taste of watermelon perfectly captures the flavor of summer, and nothing tastes as good as homegrown melons. To produce ripe fruit, watermelons, like cantaloupe, must grow in two to three months of heat, so if you live in the north, it may be tricky to know when to plant watermelon in the garden.
The world of watermelons (Citrullus lanatus) goes beyond the seed vs. seedless debate. There are four main types of watermelons, each with a delicious flavor and benefits. What interests home growers is the length of time it takes each variety to reach maturity. If you’re fighting against a shorter watermelon growing season, choosing a faster-growing type may be a perfect choice.
When you know the best time to plant watermelon seeds in your garden, the rest of the journey to bringing watermelon from the garden to your table is simple. Continue reading to find out when the best time to start planting watermelon is for your growing zone.
- When to Plant Watermelon Seeds Based on Your Growing Season
- An Overview of When to Plant Watermelon Seeds
When to Plant Watermelon Seeds Based on Your Growing Season
Because watermelon requires a warm soil temperature to ripen, it is a highly cultivated fruit grown in tropical to temperate regions. Keeping this in mind, knowing when to put seeds into the ground is crucial to ensure your melons mature correctly for the best taste once you harvest them.
Based on the average temperatures from the U.S. Department of Agriculture plant hardiness map, watermelons grow best in zones three through eleven.
Although this range covers most of the United States, other factors such as soil conditions, heat, and protection from pests all play a part in whether or not your watermelon plants make it to harvest.
An Overview of When to Plant Watermelon Seeds
For your watermelon seedlings to develop and reach the right level of ripeness, they need to grow for two to three months in temperatures between 70 and 90°F. Plant and grow cantaloupe during about the same time.
If you live in a colder climate and allowing your watermelon to grow in the ideal temperature range is a challenge, starting indoors and selecting a fast-growing variety is a workaround for this dilemma.
Cool temperatures affect the taste of your melon but allowing frost to hit your plant could mean the death of your watermelon plant. Additionally, when living in a growing zone with hot weather in the summer, short-season watermelon varieties help avoid your watermelon growing in temperatures that cause its flowers to wilt and die off.
As with most warm-season crops, when to plant watermelon seeds depends on the last frost date for your area. Depending on your growing zone, this could be from February to June.
At this point, the ground thaws and the soil in your garden is workable enough for seeds. To avoid frost or extreme heat, starting seeds indoors to prepare for transplanting becomes a lifesaver for you and your watermelons.
When to Plant Watermelon in Zone 5 and Below
To master the watermelon growing season in colder parts of the United States, search for watermelon varieties that ripen in less than 90 days. Orangeglo is a cold-hardy watermelon variety that grows in zone four with protection from a cloche or row cover.
In early May, start to sow outdoors for zone five when temperatures are likely to reach the 70s. For a jumpstart, begin planting your seeds indoors in peat pots to help minimize stress from transplanting.
Growing zones three and four cover parts of Alaska, portions of the northern midwest, and select parts of the northeastern United States. Living in this growing zone means that the average temperature won’t reach 70°F until around June or July, with temperatures tapering off in September.
Many home growers find success planting their melon seeds directly into the ground once it is workable and creating a cloche out of a plastic bottle to create a mini-greenhouse for their seedling.
A workaround to direct seeding is to start growing watermelons indoors two to three weeks before the last expected frost date, transplanting them once the soil reaches 65°F.
When to Plant Watermelon in Zone 6
For areas within zone six, although temperatures are on the rise in May, the danger of frost at night still exists that threatens your growing watermelons. If you plan on sowing watermelon seeds directly into the garden, wait until late May or June when there are no more chances for frost to hit your garden.
Like in colder areas, place yourself at an advantage by growing watermelons indoors to start. Plant your seeds deep into your pot and place them on a sunny windowsill to give them the best chance of germinating.
Once they sprout, thin seeds out until the most robust remains, and keep your watermelon plant in the window as you wait for warm weather to arrive. When your plant is sure to receive full sun on sunny days, bring them outside to acclimate them to the outdoor conditions.
To transplant with minimal risk of stressing your plant’s roots, grow in a peat pot that you can place directly in the soil in your garden. Create holes in the garden that are deeper and wider than the pot your plant is growing in. Plant watermelon far apart, since they grow very long vines and really spread. Plan your spacing of at least six feet apart.
When to Plant Watermelon in Zone 7 and Higher
For home growers in living zones seven and eight, lower parts of the midwest and parts of the south, your watermelon growing season starts in April. For zones nine and above, the growing season starts mid-March.
Because living in warmer climates comes with a longer growing season, you have the option to stagger planting. Planting more seeds allows you to harvest and enjoy watermelon longer than most.
If you plant many watermelons throughout the season, consider growing them on a trellis as watermelon vines take up considerable space in the garden and may affect the growth of nearby plants by blocking sunlight. Growing watermelon in pots is also possible if you choose a smaller variety.
When direct sowing, place black plastic over the soil to help warm it and keep it at the optimal temperature. Because your melons are spending their entire life in the garden, balance your soil to promote growth for watermelons.
Provide a sample to your local extension office and make changes by adding nutrients or aged manure to adjust the soil.
Melons enjoy absorbing water and need to remain hydrated over the growing season, so be sure to regularly check the top inch of soil if you are not using a drip irrigation system.
As temperatures rise, if soil drying out is a concern, consider adding mulch made with organic matter to keep the soil moist and minimize the need for weeding.
If you choose a smaller watermelon variety, watermelons can grow in large pots, too. Try Sugar Baby and Sugar Pot types for your containers.
Growing and Caring for Watermelons
With the right soil conditions and temperatures that remain in your favor, you’ve conquered half the battle in caring for watermelon until they harvest. Unfortunately, garden pests and diseases threaten the life of your melons.
Diseases that affect watermelons and cucurbits fall into three categories: bacterial, fungal, and viral. Viral infections tend to be worse as they infect the seed itself, and by the time you realize the condition exists, it is likely too late. Destroy the entire plant and any debris to prevent the spreading of the disease.
To combat this, shop for certified infection-free seeds from garden centers and sanitize any tools used to manage infected plants. Sanitation keeps you from unknowingly spreading the disease to healthy plants in your garden.
Other diseases are sometimes introduced to your garden by insects that serve as vectors for diseases, making regular scouting for pests crucial for the health of your crop.
Common Pests and Diseases for Watermelons
Anthracnose is a fungal disease that affects watermelons by forming dark yellow or black lesions on the surface of the fruit or brown lesions on the vine and leaves.
To avoid this disease and reduce risk, only use disease-free seeds and rotate the planting arrangement of your plants every one to two years so that cucurbits aren’t growing where another cucurbit grew last year.
Mildew diseases that affect plants cause mottling on leaves and lesions that cause leaves to curl inward. The mildew source is likely in the area near your garden that the wind or rain carried. Remove and destroy any infected plants to prevent the disease from spreading, and try growing on a trellis to promote air circulation.
Striped cucumber beetles are a problem for watermelon plants as a gathering of more than five causes severe damage to your plants’ roots, leaves, and flowers. A damaged flower is a problem because watermelon plants produce both male and female flowers for fruit production.
Should beetles damage these flowers, pollination cannot occur. Zucchini and other squashes are bad companion plants for watermelon because they bring these dreaded beetles closer to feed on watermelon vines. Insecticides help reduce the population of beetles in your garden as well as barriers such as floating row covers.
Aphids are small insects commonly found on the underside of plant leaves. Aphids secrete a sticky substance called honeydew that encourages mold growth in plants.
Because of their small size, aphids are easily knocked off plants by blasting them with a water hose. Still, insecticidal soap is just as effective without risking harming your plant or fostering bacterial growth.
Mix dish soap and neem oil. Add only two tablespoons of your mix into a spray bottle with water. When treating your plants, only mix your oil and soap with water for the amount you think you’ll use that day. Spray the leaves of your plants thoroughly to quell an infestation of aphids.
When shopping at your grocery store, you may only consider seeded or seedless watermelon as your options when bringing home this tasty fruit; however, there are over 50 varieties of watermelon.
Some of these cultivars involve pink, yellow, or orange watermelons in various sizes aside from their signature oblong shape. Different varieties also come with varying growth rates for reaching maturity, which is essential to keep in mind when determining when to plant watermelon seeds.
The 1990s saw the creation of seedless watermelon, melons with small or underdeveloped seeds that retained the sweetness of seeded varieties. However, in the process, seedless watermelon seeds suffer from a low germination rate. To ensure these types sprout, keep them warm at a constant 90°F.
As the name suggests, picnic watermelons are great for sharing with your family at a picnic. These traditional-looking melons with dark green outsides and a light rind mature in around 85 days and are likely what you’ll find stacked in the local grocery store.
Icebox watermelons are small watermelons, usually weighing around ten pounds on average. These melons have pink-red flesh or sometimes yellow and grow tough, crack-resistant rinds.
Watermelons that ripen with yellow or orange flesh may be seeded or have underdeveloped seeds (Chiffon and Honeyheart) and are typically round. These melons mature in about 75 days once their curly tendril dries out.
A good time to pick watermelons depends on which variety you grow, but is generally 80 days or so. You’ll be in for a surprise when you slice the orange ones open.
After you harvest your juicy watermelon, you may have more than you can eat before it spoils. There are a variety of ways of storing and preserving watermelons, from freezing and dehydrating to making pickles from the rinds. You’re sure to enjoy them all.
We hope you learned when to plant watermelon through our article and will share our tips on the watermelon growing season with fellow watermelon lovers on Facebook and Pinterest.