Things You'll Need
Flats of marigold bedding plants
Marigolds are annual flowers which bloom from early summer until the last killing frost. While they are often added to gardens for their cheerful yellow and crimson beauty, they can also be used to ward off certain insects. As companion plants, marigolds may help protect tomatoes from many insects, including tomato worm, whiteflies and nematodes. For the purpose of companion planting, it's easiest to use flats of marigolds and plant them at the same time or soon after you plant your tomatoes.
Break up the soil for the marigolds with a garden hoe or spade. Plant the marigolds 2 feet away from the tomato plants; if you have a large tomato garden, plant the marigolds throughout the area. For smaller gardens, plant the marigolds around the periphery of the area. The marigolds should be about 2 feet away from the tomato plants.
Dig holes for the marigolds, spaced at least 9 inches apart and as deep as they are in the flat or pot. Larger marigold varieties may need broader spacing.
Remove the marigolds from the flat or pots and place them in their respective holes. Use a spade to fill in dirt around the plants and then water them.
Water your marigolds each time you water your tomato plants. Check growing marigolds a few times a day to make sure they are not drying out. Marigolds droop and wilt quickly when they get too dry, although they may be revived through watering.
While marigolds deter many pests, they attract slugs and spider mites. Keep an eye out for these pests.
If you are also planting beans or cabbages, marigolds may act like a herbicide on these particular plants. Keep marigolds away from them.