Companion planting can help boost your garden harvest. The most common example of companion planting is the Three Sisters: corn, pole beans and squash.

Companion planting is a gardening method where vegetables, herbs and flowers are planted in proximity to each other, resulting in their improved growth and flavor. These vegetative companions offer mutually beneficial growing conditions that help each plant variety thrive in compact areas such as a backyard garden, raised beds or planters. Additionally, companion planting can provide pest control.

The most recognizable example of companion planting is the Three Sisters. This symbiotic triad consists of corn, pole beans and squash. First, the corn is planted and allowed to germinate and grow to about six to ten inches in height. Once the corn has reached this height, pole beans are planted next. The pole beans utilize the corn stalks as a support for their climbing vines. In return, the beans, known as nitrogen fixers, deliver nitrogen into the soil upon which the corn, and later the squash, will thrive. Lastly, the squash is planted. The squash's broad, spiny leaves shade the soil, provide moisture retention, protect the beans and corn from predators and create a cover for weed suppression.

Similar to the Three Sisters, there are numerous combinations of companion plants that provide mutually beneficial growing conditions for plants to thrive. Tomatoes are a summer garden favorite. Plant them with herbs such as basil, parsley, rosemary, borage and chives or vegetables such as carrots and onions. Tomatoes can also be planted with flowers such as nasturtium and marigolds. Bush beans grow well with beets, carrots, chard, summer savory, rosemary, marigolds and nasturtium. Strong companions planted with carrots include peas, beans, lettuce, chives, rosemary, sage, tomatoes and onions. Plant cucumbers with beans, corn, peas, sunflowers, borage, oregano, and radish. Companion plants compatible with onions include beets, carrots, chard, lettuce, peppers, strawberries, tomatoes, chamomile and summer savory. Squash and pumpkins thrive when planted with pole beans, corn, melon, radish, borage, marigold, nasturtium and oregano.

While companion planting has many benefits, the correct combination of vegetables, flowers and herbs is necessary. Some plants should not be combined in the garden, as they result in stunted growth patterns, susceptibility to similar diseases and pests and depletion of soil nutrients. For example, avoid planting tomatoes with potatoes, dill, kohlrabi, fennel and members of the cabbage family due to their attraction of common diseases, pests and stunted growth. Bush beans should not be planted in combination with onions, shallot and garlic due to stunted growth. Carrots should not be planted with dill, which retards the carrots' growth. Plant cucumbers away from potatoes and aromatic herbs such as sage. Cucumbers can encourage potato blight in potatoes, and aromatic herbs can inhibit cucumber growth. Do not plant onions with beans and peas, as the beans and peas may not grow as well as a result.

The science of companion planting can assist gardeners with growing healthy plants and enjoying bountiful harvests. For more information, Penn State Extension offers additional information companion planting (https://extension.psu.edu/maximizing-your-vegetable-garden; https://extension.psu.edu/programs/master-gardener/counties/susquehanna/penn-state-master-gardener-articles/good-neighbors-make-good-gardens-companion-planting). If you have questions about companion planting and other gardening practices, call the Butler County Master Gardener Garden Hotline at 724-287 4761, ext. 7 or email the Master Gardeners at butlermg@psu.edu.

Jennifer McIntire is a Penn State Master Gardener of Butler County.