What to Plant With Basil: Basil Companion Plants (and Planting Tips)

Basil is one of the easiest herbs to fit into a vegetable bed. It is compact, it grows fast once the weather warms, and it is ready at the same time as the crops it is usually cooked with. Companion lists rarely say much about basil beyond its famous partnership with tomatoes, so this guide sticks to what extension sources actually list, then covers when to plant, spacing, pinching and how to keep it from flowering.

Good companion plants for basil

Tomatoes

Oregon State, Penn State and Maryland Extension all list basil as a tomato companion. The two share the same planting window, the same need for full sun and steady watering, and the same harvest season. Tuck a basil plant between tomato cages or along the sunny front edge of the bed, where the tomatoes will not shade it. See what to plant with tomatoes. Virginia Extension also lists basil and tomatoes as companions for asparagus, so all three can share the edge of a permanent asparagus bed; see what to plant with asparagus.

Peppers

Maryland Extension suggests interplanting basil among peppers as a way to make good use of space. Peppers are set out a little later than tomatoes and like the same warm soil, so basil can go in at the same time. More in what to plant with peppers.

What not to plant with basil

None of the extension sources we use list a vegetable as incompatible with basil, so we do not show a keep-apart table here. A few practical cautions still apply:

• Shade from tall crops. Basil needs six or more hours of direct sun. Keep it on the sunny side of trellised tomatoes, corn and pole beans, not behind them.
• Crowding. Maryland Extension notes that good air circulation helps reduce basil downy mildew, so do not pack it into gaps with no airflow.
• Cool-season timing. Basil cannot go in with early peas, lettuce and spinach, because it is damaged by cold. Plant it later in the space they leave.

For pairs that sources do list as incompatible, see the keep-apart chart.

When to plant basil

Maryland Extension advises sowing basil after all danger of frost has passed, since it is not tolerant of chilly temperatures. Penn State Extension adds that the soil should have warmed to at least 60°F. If you start seeds indoors, about four to six weeks before your last frost date is a typical lead time, and transplants go out once nights stay warm. Our planting calendar puts basil with the crops planted out after your last frost.

Planting and spacing

• Sun: full sun, six or more hours of direct sun a day in summer.
• Soil: moist but well drained. Avoid heavy fertilizing; Maryland Extension notes that overly lush growth may reduce flavor.
• Spacing: in rows, thin seedlings to about 12 inches between plants and 18 inches between rows. In a raised bed, one plant per square foot works well.
• Depth: basil seed is small; sow it shallowly, about ¼ inch deep.
• Mulch: a light straw mulch once the soil is warm helps hold moisture and keeps weeds down.

Pinching and stopping flowers

Pinch stems as they lengthen to keep plants bushy and compact. A common approach is to cut just above a pair of leaves once a stem has six to eight leaves; two new stems grow from that point. Pinch off flower buds as soon as they appear, since flowering slows new leaf growth and can change the flavor. Regular picking does most of this work for you.

A simple salsa-and-pesto bed

1. Tomatoes along the north side.

   Staked or caged so they grow up, not out.

2. Peppers in the middle row.

   A listed basil companion that likes the same warm soil.

3. Basil along the sunny south edge.

   Interplanted between the peppers and in front of the tomatoes.

4. Onions at the corners.

   Listed companions for both tomatoes and peppers, planted earlier in spring.

This is the same idea as the salsa bed in our raised bed layouts, with more room for basil.

Harvest

Maryland Extension notes basil leaves can be picked about six weeks after planting. Pick from the top, cutting just above a leaf pair, rather than stripping lower leaves. Harvest everything before the first fall frost: basil blackens in cold weather, and leaves can discolor below about 40°F.

Basil in containers

Basil is one of the best herbs for pots. Use a container with drainage holes and a fertile potting mix, keep it in full sun, and water when the top inch of mix is dry. A pot also lets you move basil next to tomatoes on a patio, or indoors to a sunny window before frost.

Frequently asked questions

What grows well with basil?

Extension-listed companions for basil in our checker are asparagus, peppers and tomatoes. The table on this page explains why each pairing works.