The popular garden phrase "companion planting" refers to the art of intentionally placing certain species next to each other in your raised garden bed or soil plot in an effort to enhance their growth. Different plants can help one another in different ways, either by offering protection from pests, amplifying the delicious flavor of a vegetable or fruit, keeping weeds at bay, preserving moisture, or adding nutrients to the soil. In some instances, tall sturdy plants can even provide some much-needed structure and support for nearby vining varieties like beans and peas.
When plotting out your garden and choosing which plants to place near one another, you'll want to be sure to focus on selecting plants that have different growth habits so that they do not out-compete each other for sun and nutrients. For small gardens, strategic companion planting is also a must in order to conserve space and create as bountiful a yield as possible in a small footprint.
Both zucchini and summer squash (members of the Cucurbia pepo species) require a lot of space in the garden, making it essential to find them companion plants with opposite traits. They are also heavy feeders and require regular, even watering. Their broad leaves and vining nature can also serve a purpose for those varietals planted around them—they can keep weeds out and moisture in by providing ample shade for the soil. With these traits in mind, you can successfully choose plant companions that will thrive alongside these popular summer vegetables.
The Three Sisters
Beans, corn, and squash are the ultimate companion plants in the gardening world. This top-notch trio is typically planted together in indigenous peoples' gardens and is collectively known as "the three sisters." In fact, legend describes these three plants as "gifts from the gods," noting they should always be planted, eaten, and cherished together.
Each "sister" adds her own unique offering to the garden ecosystem. The beans (or any legume, including peas) pull nitrogen from the air and fixate it into the soil. Nitrogen-fixing plants benefit all other plants—especially heavy feeders like zucchini and squash—by providing the nutrients they need to grow. Corn, with its tall, sturdy stalk, gives vining plants like beans a backbone on which to trellis themselves.
Additionally, both corn and squash have the same moisture and soil fertility requirements, making them impeccable neighbors. The ample growth of squash and zucchini plants shade the soil and prevent the infiltration of weeds, while their spiny leaves deter rodents who may enjoy a bean or sweet corn snack.
Other Companions for Zucchini and Summer Squash
While the three sisters are common companion plants for zucchini and summer squash, they're not the only options. Mixing edible flowers and herbs into your vegetable garden will make it pleasing to the eye and can benefit your crops. Flowers like nasturtiums and marigolds act as a "trap crop" (a plant used to attract pests from another crop) for flea beetles and aphids (nasturtiums also repel squash vine borers). If you commonly deal with bugs in your garden, edge the perimeter of your squash plants with these two flowers—as a bonus, both plants bear colorful flowers that can be eaten, too. Nasturtium's spiciness adds a nip to a butter lettuce salad, while marigold's sweetness mellows out the peppery taste of arugula.
Fragrant herbs like peppermint, dill, oregano, lemon balm, and parsley help ward off pests and insects from squashes. However, take care when planting different varieties together—when strong-smelling herbs are planted side-by-side, their tastes can become altered. Additionally, two herbs that are heavy feeders can compete with each other and the squash plants for vital nutrients. On the flip side, blooming herbs like borage attract honeybees—crucial pollinators for any garden—and will increase the yield of your harvest.
Companion Plants to Avoid
While there are many plants that work great together, there are some flowers and vegetables that shouldn't be in the same plot of soil. For example, potatoes should always be planted alone, as they can negatively impact a variety of other vegetables planted nearby, thanks to their ability to deplete the soil of nutrients. For this reason, many potato farmers often rotate their crops year after year, making sure to plant nitrogen fixers in their place before reintroducing a subsequent potato crop to that same spot the following year.
Pumpkins—another unruly companion—can also wreak havoc on a zucchini or summer squash crop. As members of the same species, they can cross-pollinate in a manner that can affect the outcome of the fruit. Likewise, winter squashes (like acorn squash or butternut squash) can attract the insect pests like squash bugs to your zucchini patch and should be planted in a separate area of the garden.