Do You Plant Basil and Tomato Plants in the Same Hole or Just a Few Inches Apart?

The Science

• Planting tomatoes and basil together is supposed to be beneficial, but it's difficult to prove that theory. A West Virginia University dissertation by M.K. Bomford devised an experiment to prove that yields were greater. What he found was that basil yielded more mass when grown solo, but it was not a large percentage more. The tomatoes yielded more fruits per plant than those without basil companion plants. Some yield discrepancies in basil may be caused by larger root masses in tomatoes. From the standpoint of maximizing space, it is a good idea to plant the basil and tomatoes together.

Spacing

• Tomatoes can grow quite large and shade basil if the herb is not given enough room to itself. It can be difficult when the plants are small to guess how much extra space you'll need when they're grown. In a square-foot garden, you can plant one bush type tomato or four vines on a trellis. The highest yields in the West Virginia study came from plants with larger amounts of space between them. This indicates that it's not a good idea to plant the basil in the same hole as the tomato.

Other Factors and Benefits

• Improved crop yield and growth outcomes are affected by numerous other factors. Spacing is important but so is the soil preparation, planting times, cultivation and care -- and the ratio of herbs to fruits. In the experiment, the basil was found to have only one pest on it, which occurred more frequently when the basil was planted alone. Blind taste tests found no discernible difference in taste when tomatoes were planted alone or with the basil.

Other Planting Considerations

• Many plant combinations are said to be beneficial. However, every plant needs its own root space and room to grow. Lower-growing leafy plants need enough exposure to sunlight to perform photosynthesis. Competition for nutrients and water resources causes less vigorous plants to become puny and fail. The companion plant may not be one to drive away pollinators. Some other companion plants for tomatoes are garlic, marigold, mint, peas, parsley and chives.