Homegrown watermelon picked at the peak of sweetness tastes so much better than store-bought. Impress friends and family with your green thumb by adding this beloved fruit to your garden. Learn how to grow watermelon, and you’ll be enjoying juicy, homegrown watermelon all summer long!
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7 Tips for How to Grow Watermelon
Watermelon needs plenty of space and at least 80 days of warm temperatures to grow well. If you have both, learn how to grow watermelon with these tips.
1. Select the best variety of quality seeds for your climate and location
2. Choose and prepare a good location for planting watermelon
- Watermelon plants require a lot of space to grow and thrive, with some vines reaching up to 20 feet or more. Give them ample room. Planting at the edge of beds or growing watermelon vertically gives watermelon room to grow.
- Before planting, amend the area with compost and/or aged manure. Boost the soil further with a balanced organic fertilizer.
- Choose a site for planting that receives plentiful sunlight (at least 6-8 hours).
3. Plant watermelon seeds directly in warm soil
Wait to plant watermelon until the soil temperatures reach 21ºC (70ºF). Plant outside 2-3 weeks after your last frost date. Sow 3-4 seeds 2.5cm (1 inch) deep, 1.2-1.5m (4-5 feet) apart. Water well with seaweed emulsion after planting. Thin to the strongest plant when plants have 3-4 leaves.
If using square foot gardening, plant shorter bush varieties, plant at the end or corner of a bed, and plan on one plant per 3-4 squares.
If desired, start seeds indoors one month prior to planting outside. Because watermelons can be very frost-sensitive, it’s important to avoid planting until there is no danger of frost.
4. Water watermelon correctly for the best-tasting watermelon
- Water slowly and deeply to allow watermelon roots to grow deep. I use watering grids from Garden in Minutes to water my raised beds.
- Don’t get leaves wet. Wet leaves encourage diseases such as powdery mildew.
- As watermelon nears ripening, cut back on watering to encourage sweetness.
5. Feed watermelon throughout the growing season
- Once vines begin growing well, feed with a balanced organic fertilizer.
- When fruit sets on the plant, apply a soil drenching of seaweed fertilizer.
6. Mulch the plant and protect the fruit
Mulch plants well to prevent weeds and conserve moisture.
Once the fruit is set, use cardboard or a melon cradle to lift the fruit off the ground to protect it from pests and diseases.
Growing watermelon vertically? Use melon hammocks to support growing fruit. I use zip ties to attach the melon hammock to the trellis.
Looking for ways to add vertical space to your garden? This post shares 10 of my favorite ideas.
In this blog post, find more ways to add vertical space to your garden.
7. Harvest watermelon at the right time
Knowing when a watermelon is ripe is often the most challenging part of growing them. Here are a few things to look for:
- Three tendrils along the stem (going back to the root) end are brown, dry, hard, and curled.
- The underside of the watermelon turns creamy yellow or white.
- Low-pitched thump when you hit it lightly – practice thumping unripe melons to hear the difference.
- The sheen of the watermelon changes from slick to dull looking.