Mad About Berries

Guide to Watermelon Companion Plants

Growing plants alongside each other in many different combinations can have plenty of benefits! If the plant you’re growing is a watermelon, you may be looking for a guide to watermelon companion plants.

Watermelon plants need sandy, loose soil with pH levels between 6.0 and 6.8, 8 hours of full sunlight, and a temperature of 65-95 degrees to produce excellent fruit. With these needs in mind, plants like marigolds, nasturtiums, and radishes make suitable companion plants for watermelons.

Published: October 26, 2022.

watermelon in field

In this article, we’ll go over the proper growing conditions for watermelon, then list a few great companion plants for watermelon based on the benefits companion plants can provide!

What Are the Proper Growing Conditions For Watermelon?

Looking to get the most out of your watermelon plant? Companion plants are an important step in this process, but first, you should make sure your watermelon has everything it needs in its natural growing conditions. These are listed below:

Soil – Watermelon crops are the healthiest when the soil they are grown on is sandy and loam-based. This loose texture allows the roots of the watermelon plant to get enough air and circulation to avoid rot due to moisture or an excessively warm temperature.

pH Levels – Watermelon plants need some acidic content in their soil, which is measured by the pH levels of the soil mixture. These should be a balance no lower than 6.0 and no higher than 6.8. This way, a watermelon’s fruit will be the sweetest and juiciest it can be!

Sunlight – Almost all plants need sunlight, but watermelon plants particularly thrive on it! In fact, watermelon should be given at least 8 full and complete hours of sunlight that is unobstructed by shade every day. Without sunlight, you’ll find yourself in possession of watermelon leaves and vines but no flowers and certainly no fruit.

Nutrients – One of the main nutrients that a watermelon plant will need is nitrogen, especially when first growing. However, once the plant is old enough to flower, it is important to make sure it gets more potassium and phosphorus in its fertilizer to produce the best melons.

Temperature – When a watermelon plant is growing, it must be kept at a warm temperature not only above ground but in the soil content of the plant, too. The ideal temperature for a watermelon plant is 65 degrees at the lowest and 95 degrees Fahrenheit at the highest. Anything outside this range will stunt the growth of the plant.

Water – Because the soil of a watermelon plant is best kept wet, and the plant itself needs enough water to produce juicy melon fruits, the best amount of water to give your crop is around 1 or 2 inches of water a week.

With the correct growing conditions for your watermelon, nothing should stop the plant from becoming healthy and fruit-producing to your satisfaction! Still, companion plants, as discussed below, can also be very beneficial.

Best Watermelon Companion Plants

Now that we know what a watermelon plant needs to grow properly, we can assess which plants they can benefit from as neighbors in your garden or farm! Below is a list of companion plants for watermelons:

1. Marigolds

2. Bush Beans

3. Nasturtiums

4. Radishes

5. Alliums

6. Lettuce

Let’s take a closer look at each of these companion plants and see how they can benefit the watermelons you’re growing.

1. Marigolds

One of the superheroes of companion plants, marigolds, come in a large variety of species and colors. They may be beautiful and smell great to us gardeners and farmers, but did you know that marigolds are incredibly stinky and unpleasant to most harmful pests?

It is true! Marigolds are like kryptonite to bugs that would love to ruin your watermelon crop, including, but not limited to, cucumber beetles, whiteflies, and the dreaded aphids!


The best way to plant a marigold is as if it were a fence bordering your watermelon crop and keeping the nasty bugs out; don’t plant them right on top of or in the same pot as your watermelon plant.

2. Bush Beans

Bush beans are similar to watermelons in that they love lots of wholesome sunshine, soil that is well-drained, and soil within a very similar pH level range to watermelon soil. This makes them an ideal companion to share space with watermelon crops!

Not only that, but bush beans help in affixing atmospheric nitrogen into the watermelon plant’s soil. Get ready for a wonderful surprise: your watermelon plant can be fertilized naturally with bush beans as its companion!

It is important to note, however, that if you plan on planting alliums, another companion plant, to watermelons, you should not also plant bush beans nearby. This is because alliums actually harm the growth of the legumes that bush beans produce.

3. Nasturtiums

Nasturtium is an absolutely gorgeous flower! It is not only fabulously easy to cultivate in a garden but smells peppery and delightful. It is important not to plant nasturtiums with watermelon directly but a little further away from the crop.


This is because the most beneficial thing about nasturtiums in regards to how they help your watermelon plants is that they actually attract aphids. The idea is that the aphid pests will be so busy enjoying the smell of the nasturtiums that they won’t bother feeding on your watermelon plants.

Finally, watermelons have many great things going for them, but attracting pollinators is not one of those great things. Having a nasturtium or two around the watermelon plot will do a much better job of drawing pollinating insects toward your garden.

4. Radishes

Radishes are a diverse, easily-grown, and quick-maturing plant that make great companions to most plants, and watermelons are no exception! One of the main things that a radish contributes to the health of your fruit plants is covering the ground and suppressing weeds.

Radishes also contribute the same useful function to the garden as nasturtiums, though they may not be considered as pretty as the bright flowers: radishes attract aphids, redirecting the pest’s attention.

This may sound a little risky, inviting aphids near your garden at all, but not to worry! Radishes also bring lacewings and ladybugs around, who eat aphids, so it is truly another win-win as a companion plant.

5. Alliums

Alliums are useful to plant in any large garden. Not only are they great companions to watermelons because their canopy of leaves will not overshadow the sunshine-needing watermelons, but they repel aphids, too.


One thing sets alliums apart from the previous companion plants listed, which also repel pests, and that is this simple fact: alliums can also repel bigger predators. Deer and rats would be more than happy to sink their teeth into your garden, but once they catch a whiff of alliums, they’ll be much less likely to cause your crops trouble.

Remember, though, as previously stated, alliums should not be grown with the highly-beneficial bean plants. Though they can offer watermelon plants great benefits when planted separately, alliums and beans tend to sabotage one another when planted together.

6. Lettuce

Lettuce is useful to plant with a watermelon because not only is it a diverse crop that benefits from some of the same growth conditions, like soil levels and sunlight, but it is a short crop. This means that, although it has wide leaves, it will not create too much shade over watermelon vines and deprive them of too much sunlight.

Lettuce is best used as a companion to watermelon by interplanting. This means that you can plant lettuce, deterring weeds during the watermelon’s development, then harvest the plant in time to make room for the watermelon’s flowering maturity.

Frequently Asked Questions

Below are some questions that are frequently asked about watermelon companion plants, the answers to which you may find helpful!

What should you not plant next to the watermelon?

The worst things you could plant next to your watermelon crop are similar plants like squash, cucumbers, or even potatoes. This is because the same types of pests tend to enjoy all four of these plants.

If you plant them all near one another, it will simply wind up being a buffet to pests like aphids, spider mites, and the like!

Can watermelons be planted next to tomatoes?

Watermelons and tomatoes share many of the same needs in terms of growth conditions, such as nutrients, sunlight, temperature, and even water.

Therefore, it can be tempting to plant these crops near to one another, whether because your plot of land is limited in space or because it makes caring for them more convenient.

However, although tomatoes can be planted next to watermelons, two concerns to watch out for are the pests that may enjoy having tomato food and watermelon food so conveniently close to one another, as well as the fact that both tomatoes and watermelons need lots of space to grow properly. Make sure they aren’t crowding one another out!

What happens if you plant watermelons too close together?

Your watermelons need enough room to spread their large leaves and photosynthesize; without this room, watermelon plants tend to crowd each other out in a competition to get the most sunlight and water.

This can lead to watermelon plants failing to grow or even produce fruit.

What cross-pollinates with a watermelon?

Watermelons are part of the lanatus family, meaning they can cross-pollinate with other fruits in the same family, like citrons. Watermelon plants cannot cross-pollinate with cantaloupes or honeydew fruits, no matter how similar they may seem.

What happens if you plant a cucumber next to a watermelon?

When a cucumber plant is planted too close to a watermelon plant, you’ll be in danger of an increased amount of pests.

This is because cucumbers are close in plant-family terms to watermelon. This means that their vines won’t intertwine, but they will be a tempting meal to the same types of bugs.

Also, because they are in the same family, sometimes honeybees and bumblebees can cause cross-pollination between cucumbers and watermelons, resulting in fruit that is bitter.

How many watermelons can one plant support?

The common, single watermelon plant at full size can hold up to 4 fruits at most and 2 fruits at least. This is provided that the plant is healthy, with little to no pest damage or rot of any kind, and has plenty of space to grow.

What do you put under watermelon?

If you’ve noticed watermelon plants with a strange barrier between the actual fruits and the soil, you’ll be happy to learn why this is an intentional move on the farmer's or gardener’s part.

A watermelon plant needs a barrier of cardboard, straw, or sometimes plastic to keep the watermelons from rotting or catching diseases.

watermelons 1

Can you plant cantaloupe with watermelon?

Watermelon plants and cantaloupe may not cross-pollinate because they are actually in different plant families, but they likely will not cause each other to become unhealthy as long as they’re given plenty of space instead of crowding one another.

Therefore, it is a perfectly acceptable idea to plant watermelons and cantaloupe on the same plot of land!

Can pumpkins and watermelon plants be planted together?

Watermelons and pumpkins are actually a part of the same family of plants called “cucurbitaceae,” otherwise known as “cucurbits.”

Cucurbits all need similar growing conditions, so as long as there are enough nutrients, water, and sunshine to go around, pumpkins and watermelons will be perfectly happy growing side-by-side. Just make sure to watch out for pests!

In Conclusion

To sum it all up, watermelons produce the best fruit and thrive not only when given plenty of sunshine, one to two inches of water a week, and loose soil but the added benefit of protective companion plants.

Some of these plants, like radishes and alliums, can repel predators like aphids and even deer.

watermelon in field 2

Other plants, such as lettuce, do a great job of clearing the ground of weeds without hampering the watermelon’s growth.

Bush beans can even do your fertilizing job for you when it comes to growing watermelons! Whichever variety you choose, it is hard to deny how helpful a good companion plant can be!

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