5 Companion Planting Problems with Tomatoes

Best Companions for Tomatoes

Are you unknowingly ruining your chances of a successful tomato crop? Want to avoid the biggest mistakes when placing tomatoes near other plants in the garden?

There are several plants that may stunt tomato growth and there is one tree that could potentially kill your tomato plants! Stay clear of these vegetables and your tomatoes will grow better under less stress:

  1. BRASSICAS: Cabbage and tomatoes will get along but they are both heavy feeders and will compete for nutrients. All brassicas including cauliflower, broccoli, Brussel sprouts, kale and kohlrabi might best be grown in a separate raised bed or planted at least 3 feet away from tomatoes.
  2. CORN: Planting tomatoes alongside corn makes your tomatoes more prone to damaging caterpillars, specifically the fruitworm or earworm.
  3. FENNEL: When fennel flowers it attracts beneficial insects but that’s not a good enough reason to grow it next to your tomatoes. It may stunt tomato growth because it blocks light and will compete for water and nutrients. Some research claims it may have allelopathic properties, meaning it may be detrimental to other plants because it releases biochemical that will impact the growth of other plants. Many studies investigate the use of fennel as a weed control measure.Best Companions for Tomatoes
  4. POTATOES: “Potato” might rhyme with “tomato” but combined they are not poetry in the garden. If your potatoes start exhibiting signs of blight fungus or leaf spot, your tomatoes could be infected next. Fungus spores can travel in the wind to other plants or infect the soil through diseased tubers and fallen/decaying plant matter. Both early and late blight affects both potatoes and tomatoes.
  5. BLACK WALNUT TREE: The ultimate “no-no”, the black walnut tree, its roots and its leaves release a chemical called juglone that is toxic to many plants including tomatoes. Some studies suggest that you should plant at least 25 feet away from a black walnut tree.

For more information, check out this interesting research by M.K. Bomford, Principal Investigator and Extension Specialist in organic and sustainable vegetable production with the Kentucky State University Land Grant Program.