7 Best Companion Plants For Watermelon (And 3 To Avoid!)

You’ve probably heard about companion planting, or the idea that some crops can “help” each other out. Much of companion planting is based on observation and folklore. But a few studies have shown limited positive effects, such as using collards to attract moths away from cabbage or planting African marigolds near your squash to attract beneficials that suppress pests such as aphids.

One of the basic principles of companion planting is that it increases biodiversity in your garden to create a more balanced ecosystem. That can be achieved by companion plants in ways such as trapping pests or boosting pollination, and thus, crop productivity. On the flip side, some gardeners also believe there are plants you shouldn’t plant together.

Why You Should Plant Watermelon with Companion Plants

When it comes to watermelons, one of the most useful jobs of companion plants is to help with pollination. Watermelons are in the cucurbit family, which includes squash and cucumbers. These plants have separate male and female flowers and cannot self-pollinate. To pollinate and produce a watermelon, a bee must visit multiple times to transfer 500 or more pollen grains! Poor pollination also leads to misshapen fruit or cracks in the center of melons.

In addition, because watermelons need full sun, which is considered 6 or more hours of direct sunlight per day, companion plants for watermelons must be those that thrive in full sun. They also should not be so tall that they shade out your watermelons.

While the science isn’t strong on all plant combinations, it won’t hurt to experiment with companion planting in your garden. But remember that because every garden is different with its own microclimate, nutrient needs, and weather conditions, you’ll need to observe your plants closely to see what works (or doesn’t).

Best Companion Plants for Watermelons

Nasturtium

• Botanical Name: Tropaeolum majus
• Sun Exposure: Full sun
• Soil Type: Well-drained, moist

Nasturtiums are easy to grow from seed. They’re loved by pollinators and a potential trap crop because they’re a favorite of aphids, a common watermelon pest. Beneficial hover flies are then attracted to feed on aphid larvae.

Sweet Alyssum

• Botanical Name: Lobularia maritima
• Sun Exposure: Full, partial
• Soil Type: Well-drained but moist

This low-growing, sweetly-scented annual is a pollinator magnet. Green lacewings also are attracted to this plant, and their larvae feed on adult aphids.

Catmint

• Botanical Name: Nepeta cataria
• Sun Exposure: Full sun
• Soil Type: Well-draining, varies

This herbaceous perennial is a must-have in every garden because it’s extremely appealing to pollinators. With silvery foliage with a slightly minty scent and a profusion of purple, white or pink flowers, it’s both pretty and practical, with a long bloom time.

Borage

• Botanical Name: Borago officinalis
• Sun Exposure: Full sun
• Soil Type: Well-draining, rich

This annual herb is easy to grow from seed. It has pretty blue flowers that pollinators, such as bees, and beneficials such as parasitic wasps and hover flies, adore. One small university study showed planting borage near crops increased pollinator activity, especially of native bees and hover flies.

Dill

• Botanical Name: Anethum graveolens
• Sun Exposure: Full sun
• Soil Type: Well-draining, low fertility

This herb is easy to grow from seed, and its tall flowers on willowy stems attract pollinators and beneficials such as bees, hover flies, and lady beetles, which also enjoy dining on aphids. Of course, you can also harvest this herb for cooking.

Marigolds

• Botanical Name: Tagetes
• Sun Exposure: Full sun
• Soil Type: Moist, well-drained

These annuals come in cheery colors from sunny yellow to pumpkin orange and range in size from 6 inches to several feet tall. They bloom all summer long, attracting pollinators and beneficials such as hover flies, lady bugs, and parasitic wasps.

Lavender

• Botanical Name: Lavandula sp.
• Sun Exposure: Full sun
• Soil Type: Sandy, well drained

Lavender’s long bloom period helps keep the pollinators coming, an important reason to grow this gorgeous, fragrant perennial near your watermelon crop. Consider planting a lavender border near your garden plot.

Companion Plants To Avoid With Watermelons

Striped cucumber beetles, spotted cucumber beetles, and squash bugs are common watermelon pests which also attack other members of the cucurbit family. In order to avoid an invasion that wipes out everything, don’t plant these crops in the same family near your watermelon plants:

• Cucumbers
• Squash
• Pumpkins