How to grow herbs in a greenhouse: year-round UK guide
By Matt W. Originally published: . Last updated: .
You can grow herbs in a UK greenhouse for much of the year, but each herb needs slightly different care. Basil wants warmth, while parsley, chives, mint, rosemary and thyme cope better with cooler conditions. Use separate pots, adjust watering as growth slows, and move tender herbs indoors before frost. An unheated greenhouse can still extend autumn harvests and protect hardy plants through winter.
Key takeaways
- Grow herbs in separate pots so you can match their watering and position.
- Keep basil warm and bright; it will not tolerate frost.
- Give rosemary, thyme and sage excellent drainage, especially through winter.
- Sow coriander in small batches because each plant has a short leafy season.
- Water less as temperatures fall and growth slows.
Start with the herbs you use
Five well-kept pots are more useful than a crowded shelf. Choose the herbs you cook with, then learn how quickly each pot dries. You can add more once you know which parts of the greenhouse stay warm, bright or shaded.
Which herbs grow well in a greenhouse?
Basil, coriander, parsley, chives, mint, rosemary, thyme and sage all suit greenhouse growing. They do not need identical conditions. Basil enjoys warmth and good light. Coriander prefers cooler conditions and can flower early when it becomes hot or dry. Parsley and chives tolerate cooler weather, while rosemary, thyme and sage need free-draining compost.
Keep mint in its own pot because its roots spread quickly. Mediterranean herbs can share similar care, but separate pots remain easier to manage. You can move rosemary and thyme towards the brightest glass without forcing mint or parsley into the same dry position.
| Herb | Best greenhouse position | Watering | Winter plan |
|---|---|---|---|
| Basil | Warm and bright | Keep evenly moist | Move indoors before frost or resow in spring |
| Coriander | Bright but away from strong midday heat | Do not let young plants dry out | Autumn sowings can extend the harvest into early winter |
| Parsley | Bright light or light shade | Water when the surface begins to dry | Keep under glass for useful winter leaves |
| Chives | Bright position | Keep lightly moist | Growth may die back before returning in spring |
| Mint | Light shade | Likes more moisture than rosemary or thyme | Keep in its own pot and expect some dieback |
| Rosemary, thyme and sage | Sunny and airy | Water lightly and let excess drain | Protect pots from prolonged frost and wet compost |
When should you sow greenhouse herbs?
Spring is the easiest time to start most herbs. Sow basil somewhere warm in March or April, then move young plants into the greenhouse after cold nights have eased. Parsley and chives can also start under cover in early spring. Coriander grows quickly, so sow small amounts every few weeks instead of filling one large tray.
Late summer and early autumn offer a second useful sowing window. Coriander can provide leaves into early winter under glass. Parsley started earlier in the year can move into the greenhouse when outdoor growth slows. Rosemary, thyme, sage and mint are usually simpler to raise from young plants, divisions or cuttings.
| Season | Useful jobs | What to watch |
|---|---|---|
| Spring | Sow basil, parsley, chives and coriander | Cold nights and wet compost |
| Summer | Harvest often and resow coriander | Overheating, dry pots and early flowering |
| Autumn | Bring parsley and potted herbs under glass | Falling light and slower drying |
| Winter | Pick hardy herbs lightly and protect pots | Frost, stagnant air and waterlogging |
How should you arrange herbs in a greenhouse?
Put sun-loving herbs on the brighter upper shelf. Rosemary, thyme, sage and basil suit this position when temperatures are suitable. Parsley and mint can sit lower down, provided they still receive useful daylight. Keep enough space between pots for air to move around the leaves.
Staging keeps containers off a cold floor and makes them easier to inspect. Slatted shelves also let surplus water drain. Our greenhouse staging and shelving guide explains the main layouts. You can also browse greenhouse staging by width and style.
View and buy the Vitavia 2 Tier Silver Staging - £99
How often should you water greenhouse herbs?
Check the compost instead of following a fixed timetable. Push a finger just below the surface and lift smaller pots to judge their weight. Basil, parsley, coriander and mint use more water while they are making leafy growth. Rosemary, thyme and sage prefer compost that drains freely.
Water pots thoroughly, then let the surplus escape. Do not leave Mediterranean herbs standing in a full saucer. Morning watering gives damp leaves and staging time to dry before night. Reduce watering during cool weather because growth slows and compost stays wet for longer.
Most container herbs only need occasional feeding during active growth. Follow the product label and consider any feed already mixed into the compost. Too much feed can produce soft growth with weaker flavour. Repot crowded herbs rather than trying to correct every problem with fertiliser.
How do you prepare greenhouse herbs for winter?
Sort the pots before the first frost. Move basil to a warm, bright indoor position if you want to keep it longer. Another option is to harvest the remaining leaves and start again in spring. Parsley, chives and mint can stay under glass, although their growth will slow.
Move rosemary, thyme and sage away from roof drips and cold puddles. Raise containers on staging or pot feet so water can drain. Grouping pots together can reduce exposure during a cold spell. Wrap vulnerable containers or cover the plants temporarily when severe frost is forecast.
Ventilate on mild, dry days. A sealed greenhouse can remain damp for long periods, encouraging grey mould and rotting leaves. Water sparingly and remove fallen material. Our guide to using an unheated greenhouse through the year covers other winter crops. If you are considering frost protection, check the greenhouse heating cost guide before heating the whole space.
How do you harvest herbs without weakening them?
Pick little and often while plants are growing strongly. Snip basil above a pair of leaves so the plant branches. Take outer parsley stems near their base. Cut chives a few centimetres above the compost, leaving the centre of the clump intact.
Remove small sprigs from rosemary, thyme and sage instead of cutting deeply into old bare wood. Harvest mint regularly to keep fresh shoots coming. Coriander leaves are best picked before the plant flowers, although the seeds are also useful in the kitchen.
Use fresh herbs promptly. You can freeze chopped soft herbs in small portions. Woody herbs are easy to dry in loose bundles somewhere airy and out of direct sun. Discard any leaves showing mould or decay rather than storing them.
What problems affect herbs under glass?
Aphids gather on soft growing tips, while slugs and snails can hide beneath pots. Grey mould becomes more likely when leaves remain damp and air cannot move. Inspect young growth and the undersides of leaves whenever you water.
Start with simple corrections. Give crowded pots more space, remove badly affected material and improve ventilation. Avoid spraying anything onto herbs until you have identified the problem. Check that any treatment is suitable for edible plants. Our greenhouse pest guide can help with identification.
Frequently asked questions
Can herbs grow in an unheated greenhouse?
Yes, many herbs grow well in an unheated greenhouse. Parsley, chives, mint, rosemary and thyme cope better than tender basil. Growth still slows during cold, dark weather.
Which herbs can stay in a greenhouse over winter?
Parsley, chives, mint, rosemary, thyme and sage can remain under glass. Protect their pots from prolonged frost and keep Mediterranean herbs away from waterlogged compost.
Can basil survive winter in a greenhouse?
Basil will not survive frost in an unheated greenhouse. Move it to a warm, bright indoor position or harvest it before temperatures fall.
How often should I water greenhouse herbs?
Water when the compost begins to dry at the surface. Check each pot separately because mint and basil usually need more moisture than rosemary or thyme.
Should mint share a pot with other herbs?
No, mint is easier to manage in its own container. Its spreading roots can crowd slower-growing herbs and make watering harder to control.
When should I sow herbs in a greenhouse?
Spring is the easiest sowing time for most greenhouse herbs. Start basil somewhere warm, and sow coriander in small batches for a longer harvest.
