Our last blog post discussed the common mistakes made with raised planter beds. This blog post dives deeper into companion planting and what plants to avoid planting together. Take a look at our Gardening for Beginners blog post to help further your gardening knowledge or if you just need a refresher for this gardening season.
Plants that Should Not be Planted Together:
There is a lot of information on Companion Planting and the many benefits of it, but more importantly to know is what plants should not be planted together. It is very exciting to get a garden started, especially with some areas having a shorter planting season, but it is important to plan out your garden to ensure success.
In general, plants that should not be planted together have different reasons for their incompatibilities. For example, some plants have different nutrition needs or have specific environmental conditions. On the other hand, some plants are prone to certain pests that may affect other plants which can be detrimental to an entire section of your garden.
Tomatoes are a garden staple and loved by many gardeners. These plants are tall and vining and often attract pests which also affect nightshade plants like peppers, eggplants and potatoes. Although peppers and tomatoes are in the same family, it is not advised to plant them together. They will compete and if there is not adequate spacing between the plants, possible disease can wipe out an entire bed.
Beans do not get along with most vegetables but the plants that you should absolutely avoid are chives, garlic, leeks, and onions. They are not fans of bulb-type vegetables as well as other tall or vining plants like peppers or tomatoes.
Carrots will get along with most vegetables and really like legume and bulb vegetables. Those plants will help provide much needed nutrients. Overall, carrots do not like herbs planted with them. Avoid most herbs planted near carrots.
Asparagus loves flowering plants like marigolds and also loves herbs like parsley or basil. They will fight pests to help the asparagus thrive. A great rule of thumb is to avoid planting anything in the onion family near asparagus in order to avoid these plants fighting over soil nutrients.
Growing corn with squash and beans is common for many farmers to produce a high yield of plants. Combining corn and tomatoes is not recommended due to this plant being attacked by the same pest. These two plants also will compete for nutrients.
Broccoli and Cauliflower:
These two vegetables do not enjoy being planted with strawberries, beans and tomatoes because those vegetables can release chemicals which affect broccoli and cauliflower growth. However, plant with herbs or onions to help fight pests.
Kale has grown in popularity over the years but is very susceptible to pests in a garden. It is a good idea to plant onions, garlic, nasturtium, dill and mint herbs to help with pest control. Avoid planting tomatoes, strawberries and potatoes with kale.
Cucumbers are very easy to grow and will work best when planting near peas, beans and most cabbage vegetables. The one vegetable that cucumbers dislike is potatoes. They also are not fans of aromatic herbs like sage, rosemary, and basil.
Peppers and tomatoes belong to the same family and similar to tomatoes, peppers do not like to be planted with vegetables they can compete with. Peppers are prone to pests but much less than other nightshade vegetables. The main vegetables that are to be avoided are fennel and kohlrabi.
Although melons are in the same family as tomatoes and potatoes, they do not like to be planted together. Instead plant near corn since melons can provide a weed barrier for the corn plant. Melons grow low to the ground, so it is best planted with taller plants.
Onions do best when planted with cabbage vegetables and do very well with root crops like beets and carrots. Asparagus is the one vegetable to avoid since it will compete with the onion plant for nutrients.
Potatoes do well with many plants, especially tall and short plants like cabbage family members, corn, peas and beans. Deter pests by planting marigolds or nasturtium. Generally, potatoes do not like to be planted with spinach, cucumber, squash and tomatoes. Tomatoes and potatoes are part of the same family so they will be attacked by the same pests.
Squash is a fall favorite and does best with onions, radishes and beans. Because squash is soft, they can tend to attract many pests, so planting marigold or mint can help keep disease away. Avoid pumpkins and potatoes with squash.
Beets are another vegetable that is easy to grow and gets along with most vegetables. They mature quickly and have high yields. However, avoid planting with mustard or pole beans.
Another easy to grow vegetable that gets along with many others like beans, beets, carrots, peas, squash, to name a few. The vegetables that do not agree with radishes are broccoli, grapes, potatoes and turnips.
Eggplants benefit from nitrogen fixation so planting with legumes is great for this vegetable. Other vegetables that are compatible are potato, spinach and peppers. Black walnuts are known to interfere with eggplant growth.
Strawberries are heavy feeders and ideally like beans planted around them to get the nitrogen from the soil. Conversely if you plant them with onions, sage and thyme, they will benefit from the pest control. Avoid planting with vegetables in the cabbage family.
Peas are a great companion to most plants as they provide nitrogen to plants that need it. However, garlic and onions should be avoided because they produce a chemical that will inhibit pea growth.
Dill is an aromatic herb and is known for repelling pests. They are most compatible with onion, lettuce and cabbage but have a hard time with carrots and tomatoes.
Garlic is another staple to any garden, its pungent smell repels many pests. However, it has a hard time repelling pests from beans and peas. Do not plant these two together unless you provide a significant space between them.
Zucchini is fast growing like cucumbers and should not be planted with potatoes. Potatoes deplete nutrition in the soil so it is best to stay clear of this vegetable. Zucchini loves to be planted with beans or corn since it is a vining vegetable.
There are many reasons why certain plants should not be planted together. Above we highlighted some popular vegetables and the plants that should be planted with them, but it is also important to have a general understanding of the reason behind this.
Many plants release different levels of chemicals such as nitrogen and potassium that can directly affect the ph level of your soil. As mentioned above, some vegetables thrive off of these chemicals, while others will not survive. Some plants are also susceptible to certain pests, especially if they are part of the same family, so adding in pest repellent plants will help mitigate this.
There are general planting recommendations for every garden, for example: cucumbers thrive when planted with bush beans, lettuce and radishes, but they do not do well with potatoes. Beans, beets, cabbage, carrots, cauliflower, corn, cucumbers and strawberries make good companions to each other, but avoid including onions, garlic, leeks and shallots in the same bed. Peppers do well with carrots, eggplant, onions and parsley but do not do well with kohlrabi. Lettuce should be kept away from cabbage. Conversely, keep onions away from asparagus, beans and peas. Spinach is one of the few vegetables that is a companion to most plants.
Aside from vegetables, flowers and herbs can be great pest repellants. Using marigold, dill, nasturtiums and rosemary, can help keep pests away. Diversity your garden by adding in flowers between each vegetable. Cross-Contamination is a detriment to many garden beds which means that similar vegetables or opposite vegetables can attract certain pests that can take out your entire garden. Knowing which pests will attack specific vegetables will help you pick better companion plants.
Lastly, another important consideration is sun versus shade. Planting tall towering plants with smaller plants that are lower to the ground, will affect the sunlight that the lower plants may need. If you are challenged by space, think of planting vegetables that need the same lighting conditions with similar height, or combine shade loving small plants with sun loving tall plants.
Use the above information for specific plants to help guide you with your garden bed planning! Start small and space out your plants to avoid overcrowding, pests and cross-contamination.