The popular garden phrase "companion planting" refers to the art of intentionally placing certain vegetables, fruits and herbs 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 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 recommended in order to conserve space and create as bountiful a yield as possible in a small footprint.
The best companion plants for zucchini and squash include beans and corn, a classic combination that benefits all three plants. This combination of plants has long been known as the "three sisters" approach and was practiced by the Seneca branch of the Iroquoian American Indian nation for centuries before Europeans arrived in North America and were taught the method.
Radishes, peas, peppermint, dill, parsley, oregano, and even flowers like marigolds or nasturtiums are a few other options for gardeners. Most importantly, zucchini and squash should grow with plants that also need regular watering but don't take up too much space.
Both zucchini and summer squash (members of the Cucurbia pepo species) require a lot of room in the garden, making it essential to find companion plants with opposite traits. They are also heavy feeders. Their broad leaves and vining nature offer shade which helps keep weeds in check and retain soil moisture which will benefit companion plants with those requirements. With this 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." 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.
Giving your zucchini and summer squash plenty of space to spread out is one of the most important considerations as you plan your garden. Other cool season crops like lettuces, beets, and radishes can be succession planted in garden areas shaded from the intense summer heat.
Good companion plants for zucchini and other summer squash work in one of three ways: by repelling damaging insects, by attracting useful insects, or by improving cultural conditions for the zucchini plants. Many plants offer more than one benefit. Here is a list of helpful companions categorized according to the benefits they offer:
Pest Control Companions
- Nasturtium: Draws damaging bugs away from squash
- Marigolds: Draws damaging bugs away from squash; reduces soil nematodes
- Peppermint: Scent repels damaging insects
- Dill: Scent repels damaging insects
- Oregano Scent repels damaging insects
- Lemon balm: Scent repels damaging insects
- Parsley: Scent repels damaging insects
- Radishes: Deters squash vine borers
- Chives: Repels deer and aphids
- Calendula: Traps aphids
- Borage: Repels damaging insects
- Corn: Provides shade, offers sturdy stalks for climbing
- Sunflowers: Provides shade, offers sturdy stalks for climbing
- Peas: A legume species that fixes nitrogen in the soil
- Beans: A legume species that fixes nitrogen in the soil
- Borage; Serves as natural mulch that builds calcium in the soil
- Marjoram: Builds helpful chemicals in soil
- Chamomile: Builds helpful chemicals in soil
- Summer savory: Builds helpful chemicals in soil
Beneficial Insect Companions
- Borage: Attracts pollinators
- Marigolds: Attracts parasitic wasps that kill damaging insects
- Marjoram: Attracts bees and hoverflies
- Lemon balm: Attracts bees
- Dill: Attracts hoverflies and predatory wasps
- Calendula: Attracts pollinators
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. There are several bad companions for zucchini and other types of summer squash. For example, Irish potatoes shouldn't be planted with squash, cucumbers, pumpkins or tomatoes, as they can negatively impact a variety of other vegetables planted nearby, due 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.
It's not a good idea to mix zucchini or summer squash with another vining ground crop. For example, don't plant cucumbers and zucchini together, as the vines will become enmeshed and may even choke one another out. Similarly, it's not a good idea to plant zucchini next to other types of squash, such as pumpkins, for the same reason.
Tips for Success
Both zucchini and summer squash are heavy producers when grown in the correct conditions and this means less is often more. Two or three plants can provide enough yield for a family of four. You will enjoy a better yield with fewer healthy plants than with 5 or 6 crowded together. While you may see these plants for sale at your local garden nursery, both are easily grown by simply pressing a seed into the soil.
You may want to experiment with different companion crops until you find the perfect combination to fit your personal tastes and growing conditions. Avoid planting zucchini and summer squash with all other vining plants which include cucumbers and sweet potatoes as well as pumpkins, winter squashes, and melons.
It helps to know that these summer-type squashes tend to hide among the large leaves and vines of the plant, so check your plants daily as they begin to fruit. They can grow overnight to an unpalatable size, especially after a good rainfall.
“Companion Planting: Anecdotal or Tried and Tested?” Illinois.edu. N.p., n.d. Web.
Organic Vegetable Gardening Companion Planting. University of Florida Extension.