13 Watermelon Companion Plants

Watermelon growing with marigolds — Photo:
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Summer's sweet, juicy watermelons are easy to grow in your own backyard—with the right conditions. You’ll need warm temperatures, full sun, consistent watering, well-draining soil, and plenty of room to spread out. For optimal success, you’ll also want to add companion plants that provide mutual benefits.

Watermelon companion plants include flowers, herbs, and vegetables that will benefit your melons. They help repel bad insects and attract beneficial ones, enhance soil health, suppress weeds, provide shade and shelter from wind, and deter common diseases. They can also provide physical support, like a natural trellis, to keep fruit off the ground to reduce the risk of rot and pest damage. Companion plants can even improve your watermelon's flavor!

We asked gardening experts to share the best watermelon companion plants that will yield happier, healthier, bigger fruit—as well as which plants you should avoid growing nearby.

Tony O’Neill, gardening expert at simplifygardening.com and author of several gardening books, including the bestseller, Simplify Vegetable Gardening.
Carrie Spoonemore, co-creator of Park Seed's From Seed to Spoon app, an app that makes garden planning easier.

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Marigold

Marigolds (Tagetes spp.) are fast-growing annuals with vibrant daisy-like blooms that act as pest control. "Marigolds naturally deter pests like aphids, nematodes and whiteflies, which can harm watermelon plants," says Carrie Spoonemore, co-creator of Park Seed's From Seed to Spoon app, an app that makes garden planning easier.

Zone: 2 to 11 (varies by species)
Mature size: 6 inches to 3 feet tall
Care requirements: Full sun; well-draining soil; regular watering

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02 of 13

Corn

Tall, fast-growing stalks of corn (Zea mays) act as a natural trellis for climbing watermelon vines and provide shade and wind protection, says Tony O’Neill, gardening expert at Simplifygardening.com and author of several gardening books including the bestseller, Simplify Vegetable Gardening. "By growing corn alongside watermelons, you create a microclimate that reduces heat stress on the watermelon plants and minimizes wind damage to the vines," he says.

Zone: 4 to 10
Mature size: 4 to 12 feet tall
Care requirements: Full sun; well-draining soil; regular watering

03 of 13

Nasturtium

Nasturtium (Tropaeolum majus) is an annual trailing or climbing plant with colorful, edible flowers that repel harmful aphids, squash bugs, and whiteflies. Nasturtium also attracts beneficial bugs such as beetles. "Planting nasturtiums near watermelons can create a natural pest barrier, reducing the need for chemical interventions," O’Neill says.

Zone: 9 to 11 (grown as annuals elsewhere)
Mature size: 12 to 18 inches tall and wide
Care requirements: Full sun to partial shade; well-draining soil; moderate watering

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Borage

Borage (Borago officinalis) is a hardy annual herb with blue star-shaped flowers and coarse, hairy leaves. "It attracts pollinators like bees, which are essential for watermelon fruit set," says Spoonemore, referring to the transition from flower to fruit that requires fertilization. Borage also enriches the soil by adding trace minerals and can repel tomato hornworms.

Zone: 2 to 11
Mature size: 18 to 36 inches tall
Care requirements: Full sun; well-draining soil; moderate watering

05 of 13

Garlic

Garlic (Allium sativum) is a hardy, bulbous perennial with pungent-smelling cloves that people love but insects hate. Garlic also has natural antifungal properties that help prevent diseases such as powdery mildew, according to Spoonemore. Plant garlic between watermelon rows with a little space in between so they don’t compete for water and nutrients.

Zone: 3 to 8
Mature size: 12 to 18 inches
Care requirements: Full sun; well-draining soil; moderate watering

06 of 13

Radish

Radishes (Raphanus sativus) are fast-growing root vegetables with a spicy tang that deters aphids and cucumber beetles, which are common pests for watermelons, according to Spoonemore. They can also help break up compacted soil. As a bonus, radishes should be ready to harvest before your watermelons need the space.

Zone: 2 to 11
Mature size: 6 to 18 inches tall
Care requirements: Full sun; well-draining soil; consistent watering

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Mint

Zesty mint makes a great breath freshener—and a great repellent for aphids and ants. "Mint's strong aroma confuses pests, making it harder for them to locate the watermelon plants," O’Neill says. But be forewarned: This fast-growing herb can become invasive, so plant it in containers or raised beds so the roots won’t mingle and compete.

Zone: 3 to 11
Mature size: 12 to 18 inches tall
Care requirements: Full sun to partial shade; well-draining soil

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Beans

Beans (Phaseolus vulgaris) are legumes known for "nitrogen fixing," meaning they pull nitrogen from the air and store it in their roots, then deposit it in the soil when they decompose. "Nitrogen enriches the soil, benefiting watermelons, which are heavy feeders," Spoonemore says. They also form a ground cover that keeps the soil moist.

Zone: 3 to 10
Mature size: 1 to 10 feet tall (depending on variety)
Care requirements: Full sun; well-draining soil; regular watering

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Basil

Basil (Ocimum basilicum) is an annual herb with strongly aromatic leaves that repel aphids, thrips, mosquitoes, flies, and more. "Basil's scent confuses pests,” O’Neill says. And as a bonus, he adds, "Its flowers attract pollinators, making it a dual-purpose companion plant." For maximum pest control, plant basil between watermelon rows or on the perimeter of the patch.

Zone: 2 to 11
Mature size: 18 to 24 inches tall x 12 to 24 inches wide
Care requirements: Full sun; well-draining soil

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Dill

Another fast-growing plant that makes a great watermelon companion is dill (Anethum graveolens). This annual herb, with feathery leaves and yellow flowers, attracts beneficial insects such as ladybugs and parasitic wasps that help control pest populations, Spoonemore says.

Zone: 2 to 11
Mature size: 18 to 24 inches tall
Care requirements: Full sun; well-draining soil; regular watering

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Oregano

Oregano (Origanum vulgare) is a perennial herb with aromatic leaves that repel pests such as aphids and spider mites. "Its dense foliage can also provide shade and moisture retention for nearby plants," Spoonemore says.

Zone: 4 to 9
Mature size: 6 to 24 inches tall
Care requirements: Full sun; well-draining soil; weekly watering

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Sunflowers

Sunflowers (Helianthus annuus), the tall annuals with cheerful bright blooms, bring multiple gifts to your growing watermelon vines. According to O’Neill, their flowers attract pollinators, their deep roots help to break up compacted soil, improving soil structure, and their sturdy stems act as a natural trellis for pole beans and peas, should you be planting those nearby.

Zone: 2 to 11
Mature size: 5 to 12 feet tall x 2 to 3 feet wide
Care requirements: Full sun; well-draining soil

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Clover

Clover (Trifolium spp.) is a low-growing perennial ground cover that will enhance the soil in your watermelon patch. "Clover fixes nitrogen in the soil, improving fertility," Spoonemore explains. "It also reduces weeds and retains soil moisture."

Zone: 3 to 10
Mature size: 6 to 12 inches tall
Care requirements: Full sun to partial shade; well-draining soil; moderate watering

What Not to Plant Near Watermelon

Just as some plants can benefit watermelon growth, other plants can hurt it—by competing for resources, including water, light, and nutrients, and by attracting pests that damage both crops. Here are some plants you should avoid growing next to your watermelons.