Spacing is one of the easiest things to get wrong with herbs, because a young herb plant looks so small that the gap around it looks wasteful. A basil seedling in May is a few centimetres across, and it is tempting to plant a dozen of them a few centimetres apart. By July, those same plants are each 30 centimetres across, they are crowding each other, air cannot move between them, mildew spreads, and the harvest is worse than if you had planted half as many with room to grow.
The rule is to plant for the size the herb will be, not the size it is now. A rosemary plant that is 15 centimetres across today can be a metre across in three years. An oregano plant spreads steadily every year. Mint in open ground does not just grow — it takes over. This guide gives spacing for the common herbs, explains why spacing matters, and covers pots, beds and rows. Use our plant spacing calculator to work out how many plants fit in your space, and check your local extension service for the spacing that fits your climate and varieties.
Why spacing matters for herbs
Spacing matters for three reasons: light, air and water. A herb that is crowded by its neighbours gets less light, so it grows tall and leggy reaching for the sun, and its lower leaves yellow and drop. A crowded herb gets less air, so its leaves stay damp after rain or watering, and powdery mildew and leaf spot spread quickly through a dense, damp clump — mint and sage are particularly prone to mildew when they are packed tight. And a crowded herb competes for water and nutrients, so none of the plants grows as well as it would with room.
Spacing also matters for flavour. Herbs that are crowded and shaded produce soft, pale leaves with less flavour than herbs grown in sun with room to breathe. Mediterranean herbs such as rosemary, thyme and lavender produce their strongest flavour when they grow slowly in sun and lean soil, and crowding works against that in every way. Give herbs room, and they will repay you with healthier plants, better flavour, and a bigger harvest over the season — even though you planted fewer of them.
Spacing for common herbs
Small, compact herbs need the least room. Thyme, chives and parsley can be planted 20 to 25 centimetres apart, and cilantro and dill can be sown 15 to 20 centimetres apart in rows, thinned to that spacing. Basil needs 25 to 30 centimetres between plants, so each plant has room to branch into a bush. Mint needs a pot of its own, at least 30 centimetres across, and should never be planted direct into a bed with other herbs. Sage and oregano need 30 to 45 centimetres, because both spread steadily.
Large, woody herbs need the most room. Rosemary needs 60 to 90 centimetres between plants, because a mature plant can be a metre across. Lavender needs 60 to 90 centimetres for the same reason. Lemongrass needs 60 centimetres, and it grows into a large clump in a warm climate. Bay — if you grow it as a herb — needs room for a shrub or small tree, and it is best grown in a large pot. When in doubt, plant further apart than the packet says: a herb with room will fill the space, while a herb without room will suffer all season.
Spacing in pots and containers
In pots, the same rule applies: plant for the mature size, not the seedling size. A pot 20 to 25 centimetres across holds one basil plant, one parsley plant, or one cilantro plant comfortably — not three. A trough 40 centimetres long holds two or three small herbs, such as thyme, chives and parsley, if they want the same water — group Mediterranean herbs together and soft herbs together, and do not mix the two groups in one pot. A pot 30 centimetres across holds one rosemary plant or one mint plant, and nothing else.
Crowded pots dry out unevenly, because the plants compete for the same water, and they are harder to harvest — you cannot reach the inner leaves without damaging the outer ones. If a pot looks crowded in midsummer, it is better to move one plant to its own pot than to leave them fighting. And remember that herbs in pots need more frequent watering and feeding than herbs in the ground, because the compost has a limited supply of both — our watering calculator can help you work out how much they need.
Spacing in beds and rows
In a bed, space herbs in a grid or in rows, with the tallest herbs at the back and the lowest at the front, so each plant gets light. Leave paths or gaps between groups, so you can reach every plant to pick it without stepping on the soil or crushing its neighbours. A bed 120 centimetres wide, reachable from both sides, can hold two rows of basil or parsley with a path down the middle, or a row of rosemary at the back and a row of thyme at the front.
For herbs sown direct, such as dill and cilantro, sow in rows 30 centimetres apart and thin the seedlings to 15 to 20 centimetres apart in the row. Thinning feels wasteful, but a thinned row gives sturdy plants with plenty of leaves, while an unthinned row gives a mass of thin, weak plants that bolt early. Use the thinnings in the kitchen — young dill and cilantro thinnings are perfectly usable. Our seed spacing calculator can help you work out sowing rates and thinning distances.
Airflow, disease and the cost of crowding
Crowding is the main cause of powdery mildew on herbs, and mildew is the main reason herb leaves become unusable. Mint in a dense clump, sage packed tight against its neighbours, and oregano grown as a solid mat are all mildew waiting to happen, especially in late summer when warm days and cool, damp nights favour the disease. Space plants so air can move between them, prune or thin them to open up the centre, and water at the base in the morning so the leaves dry quickly. Our guide to powdery mildew treatment covers what to do if mildew appears, and our herbs disease prevention guide covers the full range of herb diseases.
Crowding also shelters slugs and hides pests. A dense mat of oregano or mint is a perfect hiding place for slugs in the day, and a crowded basil plant hides aphids on its inner leaves where you cannot see them. Spaced plants are easier to inspect, easier to pick, and easier to keep healthy — check your herbs weekly, turning the leaves over to look at the undersides, and you will catch problems while they are still small. If a problem does not match anything you recognise, check your local extension service for a diagnosis.
Common mistakes
The most common spacing mistake is planting for the seedling's size instead of the mature plant's size, so a bed that looked spacious in May is a jungle by July. The second is planting mint direct into a bed, where it spreads through the whole bed regardless of spacing. The third is putting three herbs in a pot that has room for one. The fourth is never thinning direct-sown dill and cilantro, so the row is a mass of weak plants. And the fifth is planting rosemary and lavender too close together, so they crowd each other within two years and the centres go bare. Plant fewer herbs, further apart, and they will grow better and taste better.
| Herb | Spacing between plants | Notes |
|---|---|---|
| Thyme, chives | 20–25 cm | Compact; good at the front of a bed |
| Parsley, cilantro | 20–25 cm | Cilantro 15–20 cm in rows |
| Basil | 25–30 cm | One plant per 20–25 cm pot |
| Dill | 15–20 cm in rows 30 cm apart | Thin ruthlessly; use thinnings in cooking |
| Sage, oregano | 30–45 cm | Both spread steadily; give them room |
| Mint | Own pot, 30 cm across | Never plant direct into a bed |
| Rosemary, lavender | 60–90 cm | Mature plants can be a metre across |
| Lemongrass | 60 cm | Grows into a large clump in warmth |
Frequently asked questions
How far apart should I plant basil?
Basil needs 25 to 30 centimetres between plants, so each plant has room to branch into a bush. In a pot 20 to 25 centimetres across, grow one basil plant, not three.
How far apart should rosemary plants be?
Rosemary needs 60 to 90 centimetres between plants, because a mature plant can be a metre across. Lavender needs the same spacing. Plant them at the back of the bed, where they will not shade smaller herbs.
Can I plant mint with other herbs if I space it out?
No — mint spreads by underground runners and will take over a bed no matter how far apart you plant it. Always grow mint in its own pot, at least 30 centimetres across, and keep the pot free-standing.
How far apart do I thin dill and cilantro?
Thin dill and cilantro to 15 to 20 centimetres apart in rows 30 centimetres apart. A thinned row gives sturdy plants with plenty of leaves, while an unthinned row gives thin, weak plants that bolt early.
Why does spacing matter for herbs?
Crowded herbs get less light and air, so they grow leggy, their leaves stay damp, and powdery mildew spreads quickly. Spaced herbs are healthier, taste better, are easier to inspect for pests, and give a bigger harvest over the season.