by Grow Northwest

Crisp, sweet, delicious watermelon. The different varieties available – from large to mini, round to oblong, red to yellow flesh, solid to striped rind – provide something for every grower’s space and preferred taste, even here in our northwest corner. We’ve been growing them in our home garden for years. Starting under warm protection in the spring, and growing through the heat of summer, watermelon will be ready to harvest within 70-100 days of planting depending on the variety.

The Sugar Baby variety is a sure producer, giving 5-10 pound fruit that is sweet and crisp with bright red flesh and mottled seed. PHOTO BY BECCA SCHWARZ COLE

There are two types of growth for watermelon: vine and bush. The vining varieties require space to spread and should be planted 5 to 6 feet apart, with 5 to 8 feet between each row. Bush varieties are more compact and should be planted 2 feet apart, in rows 3 to 6 feet apart.

Watermelon (Citrullus lanatus) love the heat and full sun, in fertile, well drained soil with a pH of 6-7. They thrive best in 8-12 hours of sunlight, with daytime temperatures of 70-80 degrees Fahrenheit, and not falling under 60 degrees at night. Providing coverage and more warmth in the early season and cooler temperatures are essential in getting watermelon started – whether using a greenhouse, hoophouse, cloche, or row cover. If you start with only a few plants, try easily protecting them with a plastic gallon jug (trim off the top and place directly over the plant). It’s a good idea to start seeds four to six weeks before they are planted outdoors in late May through mid June or buy starts to be transplanted.

When ready to transplant, be sure to work in compost and organic slow-release fertilizer into the top few inches of soil. Create small hills of mounded soil (spaced dependent on your variety’s needs). An option to increase soil temperature and stop weed growth is to place black plastic over the mounds, with a hole cut out for the plant to come through. If planting with no added protection, be sure to keep the area around the mound free of weeds.

Following are some varieties that will grow in our region. Start these seeds soon (or buy starts from local growers), and you’ll be enjoying these delicious fruits in late summer. Seed sources to consider include Osborne Seed Company, Uprising Seeds, Baker Creek Heirloom, High Mowing Seeds, Territorial Seeds, or Burpee. 

Blacktail Mountain (70 days): This early variety does well in both cooler climates and the heat and drought, making it a solid producer for our Northwest summers. The fruits may be as small as 4-5 pounds and up to 12 pounds, with a dark green rind, sweet flesh, and few seeds.

Sugar Baby (75 days): This variety is another sure producer, giving 5-10 pound fruit with bright red flesh and small, mottled seed. It is very popular and does well in our climate. We grow “sugar babies” every year and our daughter counts down until the first can be cut and enjoyed.

Beni Kodama (70 days): These mini melons are adorable and the perfect size for smaller servings. Coming from Japan, the fruit averages 2-3 pounds with dark stripes and red flesh. A good choice for short season gardeners, it does well in a large container or on a trellis with its smaller fruit and vines.

Ruby (85 days): This seedless variety has deep red flesh and is delicious in taste and texture. (The seedless varieties actually have very small white seeds in the flesh). Weighing up to 15 pounds each, the oval fruit are striped green. The plants are vigorous in the heat.

Moon and Stars (100 days): Introduced in 1926 by the Henderson Seed Company, this variety is named for its dark green rind with lots of yellow specks and a few “moons.” You’ll see yellow specks in the foliage, too! This beautiful heirloom has oblong fruits that grow 10-15 pounds, with some up to 40 pounds. The flesh is very red and delicious. Moon and Stars takes more time to grow, but worth the wait.

Yamato Cream (100 days): This Japanese variety has been described as having the flavor of Asian pear and apples with light citrus tones. The buttercream colored flesh is sweet, and the juice tastes almost pear-like. According to Baker Creek Heirloom Seeds, “It was a run-away winner in our 2018 taste test trials at the National Heirloom Exposition.” It can crack easily, so take special care when harvesting. This is a great variety for home gardeners with short travel time from garden to table.

Ali Baba (100 days): If you want a long-growing variety with heavy yields of larger oblong watermelon (growing up to 30 pounds each!), try Ali Baba. With very vigorous vines and a light green textured rind, the Ali Baba performs well in different conditions. Originating from Iraq, it is intensely juicy with sweet flavor, and a fun addition for any watermelon lover with lots of room to grow.

Royal Golden (90 days): This variety looks like a pumpkin when ready to harvest – the rind turns a beautiful golden-yellow, with delicious pinkish-red flesh. And while the color gives an easy indicator of when it’s ripe, be aware this variety can be a challenge to grow. Known for being temperamental and difficult to start, have extra special care and patience to get these ready for transplant and ultimately on your table. The Royal Garden provides a fun challenge, and worth the effort.

A few more tips

Here are a few more notes to consider when growing watermelon.

• Generally avoid overhead watering; go to the root or use drip irrigation.

• Watermelon will not ripen off the vine.

• Seedless varieties are not truly seedless; they actually have very small white seeds in the flesh.

• Cucumber beetles are a common insect problem. Use row covers for protection.

• Bacterial wilt and powdery mildew are common diseases; watch the plants to fight them. An option is using GreenCure®, a non-toxic potassium bicarbonate-based fungicide.

We’d love to hear from you! What are you growing? Email editor@grownorthwest.com.