Many vegetables & herbs can be grown with tomatoes. Companion plants are beneficial plants
that can be grown in the spaces between tomato plants. I haven't practiced much companion planting yet,
but I will mention a few that are known to enhance tomatoes.
Basil
Ocimum basilicum - Mint family
A great plant to grow with tomatoes. The flavor of basil and tomatoes is hard to beat. The two go together
very well in just about any tomato dish, and they go together well in the garden too.
Basil has been said to keep insect pests away from tomatoes. I've heard that people had fewer
hornworm problems on tomatoes that were planted with basil. Seemingly, aromatic plants like basil
and others in the mint family may deter insects. It has even been said that basil enhances
the flavor of tomatoes when it is grown with them. Definitely worth a try and easy to grow, basil
will make a valuable addition to your tomato garden.
Parsley family
Apiaceae
This family of plants includes parsley, carrots, cilantro, celery, dill, fennel, anise, and cumin.
Some plants in this family are beneficial to tomatoes, notably parsley and carrots.
Planting carrots with tomatoes may stunt the carrot roots because of competition with tomato roots,
but both will otherwise benefit from each other.
Cilantro is known to repel aphids, which often will infest tomato plants.
Onion Family
Onions, garlic and similar plants keep some pests away. Plant these around tomatoes to help keep away insect pests.
Plants to avoid
Black walnuts. If you have black walnut trees, don't grow tomatoes near them. All parts of the plant contain a substance
called juglone that is poisonous to tomatoes and other nightshade-related plants.
Crucifers (cabbage family). Cabbage and related plants such as lettuce, broccoli, and cauliflower, are bad
for tomato growth.
Fennel. Fennel has been said to inhibit growth of many other plants. It should generally
be avoided as a companion plant. Also avoid planting dill with tomatoes.
Potatoes. These are related to tomatoes (both are in the nightshade family) and they can carry a lot
of the same diseases. So if you grow one with the other, and one gets infected, then they both get infected.
Other Web sites on companion planting
Here are some Web sites with information on companion planting with tomatoes.
Basil
Parsley family