Companion planting refers to the practice of planting vegetables and herbs that benefit one another in close proximity. Every plant has it’s own characteristics and interacts with it’s environment differently. Sometimes the way certain plants interact with their environment can be beneficial to other plants. For example, peas will actually draw nitrogen from the air (with the help from a common bacteria called “Rhizobium”) and deposit it in the soil. This is beneficial to most vegetables since they need nitrogen to grow. Furthermore, Pea plants can create a windbreak that will help protect other plants.
Companion planting has been done for hundreds of years. Plants can benefit each other by attracting beneficial insects, improving the soil, pest disruption, and acting as windbreaks. Planting many different kinds of vegetable and herbs together in one garden can also help limit the spread of disease and harmful insects that may may effect one plant more than others. For example, tomatoes can provide shade for heat sensitive carrots, while carrots help break up the soil contributing to greater air circulation (according to my YouTube/Wikipedia research).
Plants for Companion Planting:
Carrots: Carrots are a great vegetable to grow in the garden due to the fact that they are relatively resistant to pests and diseases. As such, they can help act as a buffer between plants that are more susceptible to pests and disease. In doing so, preventing or limiting said pests and disease from spreading. However, it’s generally best to plant them near plants with shallow root systems such as lettuce, so that they don’t compete for nutrients. Also, lettuce repels carrot fly.
Onion: Onions do not do well with peas or beans. Also, if you live in an area where onion maggots are an issue, you should avoid planting them in tight rows. Rather, you should scatter them about your garden. However, onions do well when planted near beets, cabbage, lettuce, and strawberries.
Asparagus: According to a report by Cornell University, after harvesting asparagus, plant tomatoes on either side, and both plants reap benefits from each other. Also, planting parsley with asparagus seems to invigorate them both.
Basil: Word around town is that tomatoes and basil grow well together. Apparently, basil is known to be a somewhat effective natural deterrent for white flies, mosquitoes, tomato horn-worms, and aphids.
Sweet Pepper: Sweet pepper and basil and have similar needs and requirements. As such, they do well when grown near one another.
Radish: Radishes seem to do well at repelling cucumber beetles as well as cabbage maggots. As such, the two should be planted near one another.
Borage: The herb borage (Borago officinalis) is compatible with many garden variety plants. Borge is known to attract predatory insects such as the praying mantis and predatory wasps. Predatory insects are important for garden health, since they eat other insects that would otherwise damage vegetables and other plants.
Catnip: Known for repelling ants, flea beetles, aphids, the Japanese beetle, and squash bugs. However, apparently catnip is also known to attract cats… So there’s that.
Chives: Repels carrot fly, Japanese beetle, as well as aphids. Chive is a good companion plant for parsley, carrots, and tomatoes. Known to extend the growth the growth of carrots when planted nearby.
Fennel: Repels aphids, slugs, and snails. Fennel also know to repel fleas and attract beneficial insects.
Dill: Repels aphids, squash bugs, spider mites, the cabbage looper, and the Small White.
Garlic: Repels root maggots, cabbage looper, Mexican bean beetle, peach tree borer, and rabbits. Planting garlic between tomato plants can help protects them from red spider mites.
Lavender: Repels moths, scorpions, water scorpions, fleas, and flies, including mosquitoes. Lavender also attracts honey bees.
Narcissus: Known to repel moles.
Peppermint: Peppermint is known to repel aphids, cabbage looper, flea beetles, squash bugs, white-flies, and the Small White.
Rosemary: Repels cabbage looper, carrot fly, slugs, snails, and the Mexican bean beetle. When grown next to sage, they are known to stimulate one another.
Nitrogen Fixing Plants:
Nitrogen is incredibly important for plant growth and prosperity. As such, it’s often one the leading ingredients in most fertilizers. Nitrogen is a major component of chlorophyll, which is vital for Photosynthesis. Photosynthesis refers to the process by which plants use the energy from sunlight to produce sugar from water and carbon dioxide. Nitrogen is also a major component of amino acids, the building blocks of proteins.
There are several ways to add nitrogen to soil. The most popular methods are the use of fertilizers, compost, and manure. However, there are also what is known as “nitrogen fixing plants.” These are plants that work with micro-organisms in their roots to turn atmospheric nitrogen into nitrogen fertilizers. In short, these micro-organisms help allow these plants to take nitrogen from the air (nitrogen that otherwise would be unavailable to them) and turn it into nitrogen fertilizer.
Over time the nitrogen produced by these “nitrogen fixing” plants can become available to neighboring plants through root die back, leaf fall, and chop and drop pruning (the practice of leaving branches and leaves that have been pruned on the ground so they may be naturally composted).
These Nitrogen Fixing plants are:
Legumes: Legumes are the most cited nitrogen fixing plants. These plants include: alfalfa, clover, lentils, peas, beans, lupin bean, mesquite, carob, soybeans, and peanuts. I have read that some broccoli farmers (broccoli loves nitrogen) will plant cowpeas (a Legume) in May and then till them into the soil in August before they plant their broccoli crop.
Pea-Tree: Pea trees are incredibly hardy and can survive temperatures as low as -40 F. Due to the fact that they are relatively short and bushy, they are often used as a wind-break and for hedgerows.
Red-Alder: Alder is particularly known for it’s symbiotic relationship with nitrogen fixing bacteria. . Red Alder stands have been credited with annually supplying the soil with 120 to 290 pounds of nitrogen per acre. Alder leaves are also used as food by moths and butterflies.
Shepherdia (Buffalo-berry): Shepherdia is a small shrub native to North America. It produces edible berries that are known to be quite sour and leave one’s mouth feeling dry. However, some people use these berries to make jams and jelly. Their berries are also consumed by various wildlife.
Wisteria: Wisteria is flowering plants in the legume family. They are often used for decorative purposes and can grow up the sides of buildings. Sometimes they can reach heights of over 60 feet. Besides being a decorative plant, the Wisteria plant is known for being a good “nitrogen fixer.”