Lemongrass repay a little planning around what grows beside them. Lemongrass are a tall, clumping tropical grass with a sharp citrus scent, grown for cooking, teas and a fragrant screen at the back of a summer bed. They need full sun, soil with a pH of 6.0–7.0, 24–36 inches of space and 90–120 days to reach maturity, so their neighbours need to suit the same bed and the same season. This guide lists the companions for lemongrass from our crop data, how each one is thought to help, and which close relatives to keep apart.
There are 4 companions listed for lemongrass here: Tomatoes, Peppers, Marigolds and Cabbage. Companion planting is traditional garden practice rather than proven science, so benefits below are described in those terms — what gardeners have long said and done. Lemongrass are in the Poaceae family, need moderate water, and are started indoors and transplanted out once the weather warms; they are tender, so frost will kill them and they should only go outside once all danger of frost has passed. Check any pairing first with the companion-planting finder.
Best companion plants for lemongrass
| Companion | Why it is grown with lemongrass |
|---|---|
| Tomatoes | A tall, sun-loving neighbour for the same warm bed; plant the herb at the sunny edge so it is not shaded out, and keep spacing generous for airflow. |
| Peppers | Another heat-lover for the same sunny bed; its upright habit leaves room at its feet for low herbs. |
| Marigolds | Grown as a border or dotted through the bed; its roots are traditionally said to discourage some soil pests, and its flowers attract beneficial insects. |
| Cabbage | Lemongrass's strong citrus scent is traditionally said to confuse pests, and it makes a tall, useful bed edge. |
Tomatoes are the first companion to reach for with lemongrass, and it grows into a big clump, so it works best as a backdrop or end-of-bed plant rather than squeezed between small crops. It is the tall neighbour that sets the shape of the bed: stake it well, keep the lower leaves clear, and plant the herb at its sunny base where it gets light without being shaded out.
How companion planting works
Companion planting works through four overlapping mechanisms.
Pest confusion. Many pests find their host plant by scent. Strong-smelling companions such as aromatic herbs are traditionally said to mask that scent, so the pest passes by. It is a delaying effect, not a barrier.
Pollinator and beneficial-insect attraction. Several companions here flower — Marigolds — drawing pollinators and beneficial insects in. Let a few flower.
Nitrogen fixing. Nitrogen fixing does not apply here — none of the listed companions is a legume.
Ground cover and root layers. No companion here is a ground-cover plant, so mulch does that job instead. Deep roots beside shallow ones also compete less for water and nutrients.
None of this replaces the basics. Spacing, watering, rotation and weekly inspection matter more than any pairing.
Plants to avoid near lemongrass
The plants to keep away from lemongrass are its own relatives. Lemongrass belong to the Poaceae family, and plants in the same family share the same pests and diseases — here, aphids, slugs, cutworms — so problems pass easily between them and build up in the soil.
| Plant to avoid | Why |
|---|---|
| Sweet Corn | Same Poaceae family; shares pests such as aphids, slugs, cutworms. |
Keep these relatives in a different bed and rotate the Poaceae family to fresh ground each year.
Planting layout and spacing
One clump needs 24–36 inches and a warm, sheltered spot; in cold zones it is grown as an annual and lifted or replaced each year.
Give lemongrass their full spacing of 24–36 inches between plants. Crowded lemongrass mean poor airflow, more disease and smaller harvests, and no companion plant compensates for it. Work out how many plants fit your bed with the plant-spacing calculator or the square-foot garden planner.
Plant companions in the spaces the spacing leaves, not instead of it. Low companions go in the gaps and along the bed edges; taller ones go at the north side so they do not shade the lemongrass; scented herbs go closest to the crop, dotted through the row.
Lemongrass are started indoors and transplanted out once the weather warms: sow under cover where needed, expect germination in 10–21 days, and set plants out once the weather is right. Work backwards from your last frost date with the seed-starting calculator. Lemongrass need full sun and soil with a pH of 6.0–7.0. Water needs are moderate, so keep the soil consistently moist with deep, regular watering rather than a light daily sprinkle, and mulch thickly to hold moisture in. The watering calculator gives a starting point for your bed size. Expect 90–120 days from sowing to maturity.
Common problems and fixes
The pests most often reported on lemongrass are aphids, slugs, cutworms. Companions may reduce pressure, but they do not prevent them — inspect leaf undersides and new growth weekly and act while numbers are low.
| Problem | What you see | First fix |
|---|---|---|
| Aphids | Sap-sucking insects on new growth; leaves curl. | Wash off with water; encourage ladybirds. |
| Slugs | Chewed leaves and silvery trails, worst in damp weather. | Beer traps or copper tape; clear debris. |
| Cutworms | Caterpillars that fell seedlings by chewing stems at soil level. | Cardboard collar around each young stem. |
Aphids
Wash them off with a strong jet of water and leave ladybirds and lacewings alone to eat them. Check the undersides of young leaves, where colonies start.
Slugs
Slugs feed at night in damp weather. Clear boards, pots and debris where they hide by day, and set beer traps at soil level near the worst-hit plants.
Cutworms
Push a cardboard collar an inch into the soil around each young stem. Check beds at night with a torch when seedlings start falling.
Unsure what you are seeing? Try the pest-identifier helper or the plant-disease checker. Remove badly affected leaves and rotate the Poaceae family next year.
Frequently asked questions
What is the best companion plant for lemongrass?
The most widely recommended companions are tomatoes. A tall, sun-loving neighbour for the same warm bed; plant the herb at the sunny edge so it is not shaded out, and keep spacing generous for airflow.
What should not be planted near lemongrass?
Avoid other members of the Poaceae family, including Sweet Corn. They share the same pests and diseases as lemongrass, so problems move easily between them. Rotate the family to a fresh bed each season.
Can I plant lemongrass with peppers?
Yes. Peppers are on the companion list for lemongrass. Another heat-lover for the same sunny bed; its upright habit leaves room at its feet for low herbs.
How far apart should lemongrass and their companions be planted?
Space lemongrass plants 24–36 inches apart, and put companions in the gaps, along the edges and at the ends of rows. The plant-spacing calculator works out how many plants fit your bed.
Does companion planting replace pest control?
No. It may reduce pest pressure, but it does not replace inspection, spacing, watering, rotation and good airflow. Check plants weekly and act early.