Coriander has caught me out more times than any other herb. Twenty-odd years of growing it in Oxfordshire and I still occasionally end up with a patch of plants that bolts to seed after a fortnight, leaving me with thin yellow stems and white umbellifer flowers instead of the bushy leafy plants I was hoping for. It is the herb everyone wants to grow and the herb everyone struggles with, and the gap between “easy” coriander and “constantly bolting” coriander comes down to a handful of small things that most beginner guides skip past.
So this is the guide I wish I had read 20 years ago. How to grow coriander in the UK in a way that actually gives you usable leafy plants for months rather than five days of leaves followed by seed stalks. We will cover sowing direct (which works), sowing in pots (which works), starting indoors (which usually does not), and the bolting trick that turned coriander from my most frustrating herb into one of my most reliable.
Why Coriander Is Different to Other Kitchen Herbs
Most kitchen herbs are perennial or semi-perennial. You plant them once and they crop for months or years. Coriander is properly annual. It germinates, grows leaves for a few weeks, then flowers and seeds and dies. That is its natural life cycle and there is no fighting it. Once you accept that, growing it becomes much easier.
The job is not to keep one coriander plant going forever. The job is to keep new plants coming through in rotation so you always have young, leafy ones available. Sow a small batch every two or three weeks from April to August, and you will have fresh coriander leaves nearly all season. That single shift in approach is the difference between failing at coriander and succeeding with it. How to grow herbs in the UK covers the wider herb picture, but coriander needs its own slightly different approach.
When to Sow Coriander in the UK
Coriander wants cool conditions to grow leafy. That means the UK climate actually suits it well for most of the year, with a couple of important exceptions.
- April to early May: First outdoor sowings once soil has warmed a bit. Plants establish well in the cool spring.
- Late May to June: Continue successional sowings, ideally in part shade as days warm.
- July to early August: The risky window. Hot weather is when coriander bolts fastest. Sow in shade or skip until late August.
- Late August to September: Autumn sowings often do brilliantly. The cooling weather slows bolting and you can crop into late autumn.
- October to March: Outdoor sowing pointless. Indoor sowing on a windowsill possible but slow.
The honest truth is that my best coriander crops in the last twenty years have nearly always been from May or September sowings. The May ones because spring is cool and damp, the September ones because the heat is fading. The mid-summer sowings have been hit and miss. UK vegetable planting calendar and what to sow in May in the UK cover the wider timing.
Why Coriander Bolts and How to Stop It
This is the section every other coriander article skips, and it is genuinely the most important thing to understand. Bolting means the plant rushing to flower and seed, which causes the leaves to go feathery, the stems to thin out, and the flavour to change completely. Once a coriander plant bolts there is no turning back, and most British gardeners’ coriander attempts fail at exactly this point.
Bolting in coriander is triggered by three things, often combined:
- Root disturbance. Coriander has a long tap root and hates being moved. Transplanting seedlings is the single biggest cause of bolting. Plants that have been moved often bolt within 2 to 3 weeks of being transplanted, regardless of what else you do.
- Heat. Once daytime temperatures regularly exceed 22 to 25ยฐC, coriander reads the conditions as “summer ending, time to make seeds quickly”. UK heatwaves in July and August nearly always trigger bolting.
- Stress. Drought, overcrowding, weak soil, or being kept in too small a pot all push coriander toward flowering.
The fixes are simple once you know the causes. Sow direct where the plant will grow rather than transplanting. Use part shade in summer to keep things cool. Keep the soil consistently moist (this matters a lot more for coriander than for most herbs). Sow in a pot or patch where there is room to thin to good spacing rather than crowded clumps. Choose “slow-bolt” or “leaf coriander” varieties when buying seed, which are bred for the UK climate and bolt significantly later than ordinary seed.
Two slow-bolt varieties worth knowing: Calypso and Confetti. Both stay leafy for considerably longer than standard coriander, and both are stocked by reliable UK seed suppliers like Suttons and Thompson and Morgan. If you only buy one seed packet a year, make it slow-bolt.
Growing Coriander from Seed in the UK
Coriander is almost always grown from seed because, as I said, transplanting bolts it. The good news is the seed is cheap, germinates readily, and you really do get faster results than buying a plant from a garden centre.
Sowing direct into the ground
This is the simplest method. Wait until the soil has warmed a bit (April onwards), rake the surface to a fine tilth, and sow seeds about 1cm deep in rows or patches. Thin seedlings to about 10cm apart once they have a few true leaves. Water if the soil is dry. That is genuinely it.
If you don’t know your soil yet, how to tell if your garden soil is clay, loam or sand covers the simple tests, and how to improve garden soil in the UK walks through the longer-term improvements.
Sowing direct into a pot
Same technique, but in a 25 to 30cm pot of fresh peat-free compost. Sow a generous pinch of seeds across the surface, cover with about 1cm of compost, water gently, place somewhere with good light but not in full midday sun in summer. Thin seedlings to maybe 6 to 8 strong plants per pot once they have 3 or 4 true leaves. Peat-free compost in the UK covers what to look for, and the best compost for vegetables is worth a read before buying.
When NOT to start indoors
Most herb guides will tell you to start coriander indoors in modules and plant out. After many failed attempts at this approach I am here to tell you it is the worst possible method. Transplanting bolts coriander, every time. The plants you raise carefully on a windowsill will be flowering within three weeks of going outside.
The exception is if you sow into the actual pot the plant will live in for its whole life. That is fine, because the plant is never moved. But sowing into a tray and pricking out is asking for bolting. Skip it. Sow direct.
Growing Coriander in Pots
Coriander does brilliantly in pots if you treat it right. The key advantages of a pot are that you can move it into shade when it gets too hot, keep it watered more easily, and protect it from the worst of summer heat. Done well, a single pot can crop for six or eight weeks.
Pot size matters
Bigger than you think. Coriander has that long tap root and a 30cm deep pot is a sensible minimum. Wide and shallow does not work. Tall and narrow is closer to what you want. A pot with at least 30cm of depth lets the roots develop properly, which delays bolting and gives stronger leaf growth.
The smaller the pot, the faster the plant feels stressed and the quicker it bolts. This is genuinely the single biggest cause of coriander failure in containers. Growing vegetables in pots in the UK covers the wider container principles, and the best vegetables to grow in pots includes coriander among the herbs that work well in containers.
Position
Morning sun and afternoon shade is honestly the sweet spot. Full sun works in spring and autumn but cooks the plant in mid-summer. Part shade slows bolting and keeps the leaves tender. If you only have a sunny patio, position the coriander pot behind a taller plant or against a wall that gets some shade later in the day.
Growing Coriander Indoors
Coriander on a windowsill works better than people expect. It actually likes the cooler steady conditions indoors better than the heat and unpredictability of outdoors in summer. A south or south-east facing windowsill, a decent-sized pot, and regular watering will give you a six to eight week crop indoors in winter when nothing much is growing outside.
The main indoor risk is the same as outdoor: bolting. Indoors this is often triggered by heat from a radiator, low humidity, or the pot drying out. Keep the plant somewhere cooler if possible, not directly above a heat source, and water consistently. A pot of coriander grown by a window from September onwards can give you fresh leaves right through to Christmas, which is genuinely useful.
Don’t try to keep supermarket coriander pots going for long. Like supermarket basil and parsley, those pots are crammed with seedlings designed to be eaten within a week. They are not made to grow on. Better to sow your own seed in a proper pot.
Watering and Feeding Coriander
Consistent moisture is the single most important thing for stopping bolting and keeping the leaves tender. Coriander hates drying out. In pots especially, check the compost every couple of days in summer and water when the top centimetre feels dry. How often to water plants in the UK covers the wider principles, but for coriander I would say err slightly on the side of moister than you would for other herbs.
Feeding is barely needed. Fresh compost has enough nutrients for the few weeks coriander is growing. Heavy feeding can actually push the plant toward flowering by speeding up growth. If you have a long-cropping plant in a pot, a light liquid feed every three or four weeks is plenty. Feeding vegetables properly in the UK covers the wider principle.
In a heatwave, move pot-grown coriander into shade and water in the morning and evening rather than midday. Protecting garden plants during heatwaves covers the wider summer care, and why vegetable plants wilt in UK gardens covers the wilting that can come from heat versus dryness.
Harvesting Coriander to Keep It Going Longer
The way you harvest matters more than people realise. Snipping leaves off the top is fine for occasional use but it actually shortens the plant’s productive life. The better technique is to cut whole stems from the outside, leaving the smaller central leaves to keep growing.
Better still, cut the whole plant back by half once it has 8 to 10 true leaves. This sounds drastic but it forces the plant to push out fresh leafy growth from the base rather than racing upwards toward flowering. You lose a week of harvesting but you gain three or four weeks of cropping at the end. I have got plants going for eight weeks this way that would have bolted in five if I had been gentler with them.
Once you see the first flower stems appearing (tall, thin, with smaller feathery leaves), the leaf game is up. At that point either pull the plant and start fresh from a new sowing, or let it go to seed and harvest the coriander seeds when they turn brown. Coriander seeds are useful in their own right for curries and pickling, and they save themselves for next year’s sowing.
Companion Planting and Pests
Coriander grows happily alongside most things and is genuinely useful as a companion plant. The flowers, when you let them happen, attract beneficial insects like hoverflies and parasitic wasps that prey on aphids, which the RHS has good detailed advice on. So even bolted coriander has a job to do in the garden, which is some consolation when your latest batch has run to seed.
Pests are rarely a serious problem. Slugs can take young seedlings in damp conditions, so worth protecting in the first couple of weeks if your garden has heavy slug pressure. Aphids occasionally turn up on stressed plants. A blast of diluted soapy water deals with both. Otherwise coriander is one of the more trouble-free herbs to grow.
Saving Coriander Seed
If a plant bolts (and it will), let it. The seeds it produces are not only useful for cooking but will also grow next year’s plants for free. Leave the seed heads on until they turn light brown, then cut the whole flower stalk off and hang it upside down in a paper bag in a dry place for a fortnight. The seeds will drop into the bag as they finish drying. Store in a jar in a cool dark place and you have got next year’s coriander supply.
One sown plant left to flower will often give you 30 to 50 seeds, more than enough for the following year. After a couple of seasons of saving seed I haven’t bought a fresh packet of coriander in years, except occasionally to bring in a new slow-bolt variety.
Coriander Through the Year
March. Too early for outdoor sowing in most of the UK. Plan and prepare beds.
April. First outdoor sowing once soil has warmed. Direct sow in pots or beds.
May. Continue successional sowings every two or three weeks. This is the best month for new sowings. What to sow in May in the UK covers what else is going in.
June and July. Sow in part shade to avoid bolting. June gardening jobs in the UK covers wider summer care.
August. Skip new sowings in hottest weeks. Resume late August.
September. Best month for autumn sowings. Cool weather slows bolting and crops well into late autumn.
October to February. Outdoor sowing pointless. Move to indoor windowsill sowings for fresh winter leaves. Save seed from any plants that have bolted and gone to flower.
Common Coriander Problems
- Plant bolting within 2 to 3 weeks. The classic problem. Causes: transplanting, heat, drought, small pot. Use slow-bolt seed varieties, sow direct, keep watered, move to shade in summer.
- Yellow lower leaves. Usually overwatering, sometimes nutrient depletion in old compost.
- Leggy weak plants. Not enough light, or sown too thickly. Thin seedlings ruthlessly.
- Plant looks fine then collapses. Almost always damping-off (a fungal seedling disease) caused by overwatering or stale wet compost. Sow into fresh compost, water from below.
- Seeds not germinating. Coriander seed loses viability fast. Use fresh seed from a recent packet, not the bottom of last year’s tin.
Common Questions About Growing Coriander
Why does my coriander keep bolting?
Bolting in coriander is triggered by root disturbance, heat, drought, and stress. The biggest single cause is transplanting seedlings, which sets the plant off bolting within 2 to 3 weeks. To prevent it, sow direct where the plant will live, choose slow-bolt varieties like Calypso or Confetti, grow in part shade in summer, and keep the soil consistently moist.
When is the best time to sow coriander in the UK?
April to May is the best spring sowing window, once the soil has warmed slightly. Late August to September is an excellent second window, often producing better crops than mid-summer sowings. July and August sowings tend to bolt fast in hot weather unless grown in shade.
Can you grow coriander indoors in the UK?
Yes, and it often works better than outdoor summer growing. Coriander likes cool steady conditions, which a UK windowsill provides well from September through to spring. Sow direct into the final pot, choose a south or south-east facing window, keep the compost moist, and avoid placing the pot above a radiator.
How long does coriander take to grow?
Coriander seeds typically germinate in 7 to 14 days. From sowing to first harvest is around 4 weeks, and a well-treated plant will keep cropping for 6 to 8 weeks before flowering. Sowing a new batch every 2 to 3 weeks keeps a steady supply going through the season.
Should I sow coriander in modules or direct?
Direct, always. Coriander has a long tap root that resents being disturbed, and transplanting from modules nearly always triggers bolting within a couple of weeks. Sow into the final pot or bed where the plant will grow, then thin seedlings rather than moving them.
Does coriander prefer sun or shade?
In a UK summer, part shade is much better than full sun. Morning sun with afternoon shade is the sweet spot. Full sun causes heat stress and rapid bolting in July and August. In spring and autumn full sun is fine because the weather is cooler.
Can I save seed from a coriander plant?
Yes, easily. Let a bolted plant flower and seed. Wait until the seed heads turn light brown, cut the whole stalk, and hang it upside down in a paper bag in a dry place for two weeks. The seeds drop into the bag. Store in a jar in a cool dark place and they will sow the following year.
A Sensible Place to Start
If you have never grown coriander, here is the plan. Buy a packet of slow-bolt seed (Calypso or Confetti). In April or May, sow a generous pinch into a 30cm pot of fresh peat-free compost. Stand it somewhere with morning sun and afternoon shade. Water whenever the compost feels dry. Thin the seedlings to about 8 plants per pot once they have a few true leaves. Start harvesting once stems are 15cm tall, cutting the outside ones first.
Sow another pot three weeks later. Then another three weeks after that. By high summer you have got three pots at different stages, two cropping while the third grows on. That single rotation keeps fresh coriander coming for nearly the whole growing season. Twenty years in, this is still the most reliable system I have used.
To build a wider herb collection, how to grow herbs in the UK covers the full picture, and the cluster guides for parsley, mint, chives, and basil walk through the other kitchen essentials. Gardening for beginners in the UK covers the wider first-year approach if coriander is your first proper crop.