Best Watermelon Companion Plants

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Shaleena Quinlan

Shaleena grew up working the garden with her grandmother. These are some of her favorite childhood memories. She credits the long line of midwestern farmers that passed the knowledge down to her grandmother and then her and her inherent green thumb for her talent with growing plants. Her talent for training plants has followed her to various places, including Papa New Guinea's tropics. She's learned various techniques for all types of growing zones and is excited to help you build the best garden for your home!

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Watermelon is one of my favorite fruits to grow and eat, so I am always looking for gardening tips and tricks to help me grow better watermelon. The moment I discovered that there are companion plants for watermelon, I was thrilled. With this lovely bit of information by my side, I knew my watermelon garden would be fabulous.

Since I am not sure if you are familiar with the concept of gardening with companion plants, I thought it might be nice to give you a brief description. This type of gardening takes the attributes of a plant and utilizes them to help other plants in the garden grow better.  Let’s look at one very famous example.

Perhaps you have heard of the celebrated three sisters planting arrangement. This is an indigenous American garden arrangement that typically incorporates corn, squash, and beans, but sometimes sunflowers. In this arrangement, the corn stalks or sunflowers supply a support system for the beans to vine around.

The squash leaves provide shade and mulch for the beans and corn. Meanwhile, the beans supply nitrogen to the soil. I think this is a brilliant example of how gardening with companion plants is so beneficial.

Now that everyone is familiar with the concept of gardening with companion plants, we can move along to discuss specifics. In this article, I want to present the best watermelon companion plants for the many growing needs of these fruits. But, I also want to talk about the plants that should never be grown next to watermelon and why.  Once you finish reading this article, you should be able to grow a fabulous harvest of watermelon.

Bottom Line Upfront

If you’re scrambling for time, you may want to save this article for later and just read this short summary.

• Use legumes and sunflowers to improve your garden’s soil
• Use flowers and herbs to attract pollinators to your garden (thyme, oregano, etc.)
• Use flowers and herbs to repel pests from your garden (garlic, catnip, etc.)
• Avoid planting certain plants that attract pests (cucumbers, squash, etc.)

Of all the companion plants on this list, I’ve found that mint is my absolute favorite.  This herb repels harmful insects, attracts pollinators, and is delicious when cooking special treats.  I think you’ll find that you like it best of all too.

Best Companion Plants for Soil Improvement

We all know that nitrogen is essential for growing healthy plants. When I find that the soil in my garden is lacking sufficient quantities of nitrogen, I just plant some legumes. These companion plants not only fix the nitrogen levels in my soil but also provide some extra nutrients for my cooking. Here are two legumes that I highly recommend as companion plants for watermelon.

One important thing to note about growing legumes is that they should not be planted near anything that is in the allium family. This includes onion, garlic, and chives. If you do, you’ll find that the growth of the legumes is greatly inhibited.

Bush Beans

I prefer to grow this type of bean because the plant won’t cast a large shadow over my watermelons. Remember, watermelons need full afternoon sun to grow properly. Bush beans grow into small bushes and produce either snap beans or greens beans.  

If this is a companion plant that interests you, here are some important growing specs to consider:

• USDA Hardiness Zones: Bush beans grow well in zones 3 to 11.
• Soil Type: Bush beans require clay or silty soil with temperatures ranging between 70-80°F and pH levels ranging between 6.0 and 7.0. Also, the soil should be able to drain off excess water.
• Water: Bush beans like their soil moist but not soggy. This can be accomplished by watering them twice a week and regularly checking the moisture of the soil. To help prevent plant rot and other water-related diseases, I recommend that you water bush beans early in the morning. This allows excess water to dissipate throughout the remainder of the day.
• Fertilizer: Since bush beans make their supply of nitrogen, they don’t require a lot of fertilizer. I do, however, think they benefit from giving them worm castings and manure.  
• Sun Exposure: Bush beans require 6 to 8 hours of full sun every day and daily temperatures ranging between 65-85°F. Keep this in mind when you select a garden plot for your beans.
• Sowing & Harvesting: Bush beans should be sown after the threat of frost has passed. These beans can be sown every two weeks in warm weather to spread out and extend their harvest time. Seeds should be placed 1” deep and 18” apart. Depending on which variety you plant, the beans should be ready to harvest in 50 to 60 days.
• Growing Tip: I suggest you provide each bush bean plant with plenty of personal space to grow. They need room to spread out, get air into their leaves, and soak in the sunlight.

Pole Beans

Because of my love of green beans, I enjoy growing pole beans. These plants are both nutritious food for humans and garden soil.  Plus, they are easy to grow. Just give them a little space and plenty of sunlight and let them go.

If this is a companion plant that interests you, here are some important growing specs to consider:

• USDA Growing Zones: Pole beans will grow well in zones 2 to 11.
• Soil Type: Pole beans require soil temperatures that are at least 60°F for proper germination.
• Water: I use an irrigation system to water my beans so that the soil is moistened, not the leaves. This avoids issues with soggy soil or plant rot from too much moisture. Just like bush beans, pole beans should be watered twice a week during morning hours.
• Fertilizer: These are just like bush beans when it comes to fertilizer. I avoid nitrogen-rich fertilizers and just opt for manure or worm castings when I feed any beans in my garden.
• Sun Exposure: Set these plants in a place that receives 6 to 8 hours of full sun every day.
• Sowing & Harvesting: Pole beans can be planted once outside temperatures reach 60°F regularly, and the threat of frost has passed for the season. Seeds should be placed 1” deep and 8” apart.  Most pole varieties are ready to harvest 60 to 70 days after sowing.
• Growing Tip: Remember to provide pole beans with a stable and upright structure for them to vine around. Anything tall and sturdy will do, but I prefer this bean tower.

Sunflowers

If there is one flower that I could have in my garden every year, it would be the humble sunflower. While they are busy providing beauty and a healthy snack for harvest time, they also manage to improve soil conditions and pull in a bunch of beneficial insects to pollinate the rest of my garden.  

This lovely flower is known for its ability to remove heavy metals from soil. So, if you find that your garden soil has too much arsenic, chromium, lead, or zinc, plant a few of these for a season. Sunflowers work hard in the garden, and this is why I love them so much.

If this is a companion plant that interests you, here are some important growing specs to consider:

• USDA Growing Zones: Sunflowers grow well in zones 4 to 9.
• Soil Type: Plant your sunflowers in well-draining soil that has a pH level between 6.0 and 7.5.
• Water: As sunflowers grow, they will require less water. When they are young sprouts, make sure they are kept in moist soil, but hold back on watering when they grow larger. I usually water the mature sunflowers once a week. When I do this, I ensure that their root systems are watered deeply.
• Fertilizer: Sunflowers do not require much fertilizer, but if you feel that yours could use some, I recommend Hunt’s Harvest Plant Fertilizer.
• Sun Exposure: These flowers worship the sun, so give them plenty of it. 6 to 8 hours a day is perfect.
• Sowing & Harvesting: Sunflowers should only be planted outside after the threat of frost has passed for the season. Seeds should be planted 1” deep and 6” apart, then trimmed to 12” apart once sprouts appear.  Most sunflower varieties will be ready for harvesting between 80 and 120 days after sowing.
• Growing Tip: Large sunflower varieties may need a stake to support the weight of their stalk and seed head. Also, sunflowers will attract aphids, so it is best to plant these near your watermelon garden but not within reach of the watermelons.

Best Companion Plants for Attracting Pollinators

Watermelon plants need to be pollinated to produce fruit. Yes, this can be done manually, but why bother?  Instead of brushing pollen on watermelon blossoms, I prefer growing attractive flowers and herbs that pollinators cannot resist. If you agree that it is much better to let nature handle watermelon pollination, I recommend you try some of my favorites:

Marigolds

I love marigolds. They look amazing, and they smell amazing. That is probably why pollinating insects enjoy them as well. If you want a garden full of beautiful sights, smells, and pollinators, then plant a few of these lovely flowers.

If this is a companion plant that interests you, here are some important growing specs to consider:

• USDA Growing Zones: Marigolds grow well in zones 2 to 11.
• Soil Type: Provide your marigolds with slightly acidic soil (pH levels between 6.0 and 7.0) that drains well.
• Water: Marigolds need more water while they are in the seed and small sprout stages. As they mature, they are fairly drought tolerant. I’ve found a good rule of thumb is to keep their soil moist, but not soggy, while they are young and water them once a week when mature.
• Fertilizer: I don’t typically fertilize my marigolds. If your soil is not nutritious enough to grow these flowers, you can get a general fertilizer such as Miracle-Gro.
• Sun Exposure: These flowers love heat and sun so make sure they are set in a warm place for several hours a day.  
• Sowing: Marigolds are easy to plant since they can be started indoors on a seed tray. Once they are strong enough and the weather is warm enough, they can be transplanted outdoors. The best time to plant them outdoors is after the threat of frost has passed.
• Growing Tip: If you want your marigold plants to grow bigger and fuller with blooms, try deadheading them. Also, don’t plant marigolds directly next to watermelon; instead, plant them on the perimeter of your garden.

Lavender

Growing lavender is more than just a way to encourage pollinators to help with my watermelons. I love to use this flower in dried flower arrangements and homemade beauty products.

If this is a companion plant that interests you, here are some important growing specs to consider:

• USDA Growing Zones: Lavender will grow in zones 1 to 10.
• Soil Type: Lavender does not need highly nutritious soil but does like soil with a pH level of 7.0.
• Water: When lavender plants are young, give them enough water to moisten their soil. As they get older, there is no need to water them unless they are beginning to dry out too soon.
• Fertilizer: I never fertilize my lavender plants because I risk injuring them if I do.
• Sun Exposure: I plant my lavender in areas that get full sun in the morning but offer a little shade in the afternoon.
• Sowing & Harvesting: If you live in zones 1 to 6, plant your lavender in early springtime. If you live in zones 7 to 10, plant your lavender in late autumn. These timeframes allow the plants to establish roots without freezing them.
• Growing Tip: I usually deadhead a few of my lavender plants, so they produce more blooms. But, I also let a few of them self-propagate so that I have new baby lavender plants next year.

Mint 

This is my favorite companion plant listed. I love mint because it smells so amazing, I can use it when cooking my favorite desserts and drinks, and it brings a lot of pollinators into my garden.

If this is a companion plant that interests you, here are some important growing specs to consider:

• USDA Growing Zones: Most varieties will grow well in zones 3 to 11. Check which zone you are in to find the best mint variety for your area.
• Soil Type: Mint grows best in soil that is loamy, well-draining, and has a pH level range of 6.2 to 7.0.
• Water: I check the dryness of the soil around my mint plants before I water them. If I feel that the soil up to an inch deep is dry, I will water my plant. Since mint plants don’t do well in soggy soil, I don’t water them unless they need a drink.
• Fertilizer: You will probably never see me giving fertilizer to my mint plants because they rarely ever need any. However, if I notice that my plants could use some extra nutrients, I will give them Dr. Earth Organic Fertilizer.
• Sun Exposure: When I selected a place to plant my current mint plants, I made sure they would get plenty of morning sun while being shaded from the scorching afternoon sun. Mint plants do need sunlight, but too much can burn them.
• Sowing & Harvesting: Since mint thrives on springtime rain, I usually plant mine sometime before the rain begins but after the threat of frost has passed. It does not take mint very long to grow and begin producing leaves. Once the leaves are plentiful, I trim a third of them off the stalk for use in tea or homemade ice cream.
• Growing Tip: Never harvest more than a third of your mint leaves at a time. If you take off too many leaves, the plant will struggle to grow more.

Oregano

When I lived in Greece, we put oregano in everything. I threw it in fresh salads, on toast, and in yogurt dips and pasta sauces. This herb is easy to eat and even easier to grow.

If this is a companion plant that interests you, here are some important growing specs to consider:

• USDA Growing Zones: Oregano grows well in zones 4 to 10.
• Soil Type: What I love about oregano, other than its flavor, is that it will grow in poor-quality soil. So, when I have a space in my garden that is only so-so, I will stick some oregano there. I do make sure that the soil is well-draining and has a pH level somewhere between 6.0 and 7.0. Otherwise, this is a very easygoing plant.
• Water: I have found that my oregano plants only need water once a week unless it is excessively hot outside. When I do water them, I water them at the soil level and ensure that the roots are watered deeply.
• Fertilizer: I avoid fertilizing my oregano plants because some chemicals can alter the plant’s flavor. Plus, this plant grows better in poor soil.
• Sun Exposure: These are plants that can handle six hours of full sun every day, so I provide that for them.  If I feel like the afternoon sun is burning them, I will either move their container to a shady spot or set up a sun shade.
• Sowing & Harvesting: I typically start growing my oregano plants indoors for about two months before taking them outside. They don’t do well in cold weather, so I wait until air and soil temperatures are about 70°F. Harvest time, or should I say pasta time, begins when the plant is around 5” tall and has a plethora of fragrant leaves. As with my mint plants, I try to pluck off only a third of the leaves at a time.
• Growing Tip: If you are careful, you can overwinter oregano plants so they will return in the spring. This way, there is no need to buy new plants each year.

Thyme

Here is another herb that I love to use in cooking as well as gardening. Any chicken dish will benefit from a few sprigs of thyme, so be sure to plant plenty.

If this is a companion plant that interests you, here are some important growing specs to consider:

• USDA Growing Zones: Thyme plants grow best in zones 5 to 9, but they can be grown indoors in any zone.
• Soil Type: I put my thyme plants in sandy soil that drains well. Also, I make sure the soil’s pH levels range between 6.0 and 8.0.
• Water:  I love this herb because I don’t have to worry about watering them every single day. I typically water my plants every other week. Before I water them, I do a soil test to ensure that they need water.  If the soil is still moist, I wait a few more days to water them. When I do give them water, I pour it on the soil and allow it to run deeply to the root system.
• Fertilizer: This herb isn’t a heavy feeder, but if my plants do look a little malnourished, I will give them a half-dose of Spade to Fork Organic All-Purpose Fertilizer.
• Sun Exposure: Thyme is similar to oregano when it comes to sun exposure. I set my thyme plants in areas where they get six hours of full sun each morning and shield them from the afternoon sun.
• Sowing & Harvesting: I typically bring my thyme plants outside once there is no threat of frost. As with mint and oregano, I only trim a third of the plant at a time so it can continue growing.
• Growing Tip: Thyme is an awesome plant to grow all over your yard. If you live in the right growing zone, you can create a thyme lawn.

Best Companion Plants for Repelling Pests

It isn’t just humans that find watermelon tasty – bugs do too. Fortunately, there are some natural ways to keep those pesky insects away from your melons so can enjoy the fruit of your labors. Here are a few pest-repelling companion plants that I recommend you try.

Catnip

Grow some of this if you want to keep your watermelon garden free of aphids and possibly mosquitos.

Corn

If your watermelons are under attack from cucumber beetles, try planting a few stalks of corn nearby. It will be a minor sacrifice, but I think it is worth it.

Dill

I love this herb because it is great to use on lox and bagels, plus it repels aphids and spider mites.

Garlic

You know you’re going to use this with the oregano and thyme you’re already growing, so this is an easy yes. Plant some garlic near your crop of watermelon to deter aphids from the area.  

Growing Tip: If you have planted legumes to help with the soil in your garden, don’t plant garlic or any other member of the allium family near the legumes. Alliums inhibit the growth of legumes.

Marigolds

Another reason to plant marigolds along the border of your garden is so they will repel cucumber beetles. 

Mint

This herb works double duty to attract pollinators and repel aphids. I highly recommend you plant this all over your garden.

Nasturtiums

These edible flowers are natural repellants to both aphids and cucumber beetles. I think they are a garden essential because of this.

Radish

I love these peppery little bulbs on cold salads and next to my watermelon garden. With radishes all around, I know my melons are safe from cucumber beetles.

Plants to Avoid

Now that we have thoroughly discussed which plants offer help and protection for watermelon gardens, we must talk about the plants to avoid growing next to watermelons.

Most of the plants listed in this section should be avoided because they and watermelon face similar diseases and pest infestations. If you intend to plant any of the following, be sure they are set far away from your watermelon plants, or you might face some major issues.

Cucumbers

These attract cucumber beetles. Avoid seeing both your cucumbers and your watermelons eaten up together simply by planting these far away from each other.

Potatoes

These attract several types of aphids. For the safety of your potatoes and your melons, separate them from each other in the garden.

Pumpkins & Squash

Both of these attract beetles, so avoid planting them near your watermelons.

Sunflowers

While these are great for attracting pollinators to your garden, they will also attract aphids that will destroy your watermelons. As I mentioned earlier, it may be best to plant your sunflowers at a distance to reap the benefit of pollinators but avoid an aphid infestation.

Roses

These also attract aphids.

FAQs

Concluding Thoughts

Discovering the best watermelon companion plants has been a boon for my garden. Because of these garden helpers, I have been able to grow healthy and juicy watermelons without stressing over soil nutrients, pollinators, or pest infestations. I am so excited to try out new companion plants alongside my favorite, mint, as I till out more soil to grow more produce.

Hopefully, the information in this article has benefitted you as well. I hope that you will be able to utilize this information to grow the best harvest of watermelon you have ever had. If you want to learn even more about the plants in your garden, check out all our guides at JardinHQ.

Research Citations:

• Gardening Know How
• Almanac
• Gardeners Path
• American Meadows