How to Grow Coriander: A Practical Guide from Seed to Harvest

Coriander is one of those herbs that's easy to grow, but it doesn't always behave quite how you expect. The seeds germinate readily and the plants grow quickly, but warm weather can suddenly send them into flower just when you've got used to picking the leaves.

I prefer to sow small amounts regularly rather than trying to keep one batch of coriander going all summer. That way, when one lot starts flowering, another is coming along behind it.

Coriander grows well in the ground, raised beds and pots, so you don't need much space. Give it reasonable soil, regular water and a little protection from the hottest summer sun and you'll usually get a good supply of fresh leaves.

And if a plant does run to flower, don't immediately pull it up. The flowers are useful for pollinating insects and, if you leave them, you'll eventually get coriander seeds to harvest too.

When to Sow

Coriander has quite a long sowing season, but I wouldn't sow a huge amount at once.

You can start under cover from February or March if you want an early crop. I often sow a pot and put it on the windowsill. From around April, sow directly outside as the soil begins to warm, then continue with small sowings every few weeks through spring and summer.

Succession sowing really is worthwhile with coriander. A short row or a pot every three or four weeks will give you a much steadier supply of leaves than one big sowing.

During hot summer weather, coriander can bolt very quickly. If you have a spot that gets some afternoon shade, it's a good place for your summer sowings.

You can sow again towards the end of summer and into early autumn. As temperatures cool, plants are generally slower to flower and you can often get some lovely leafy growth.

And if you've missed an earlier sowing, don't worry. Coriander grows quickly enough that there's usually time to start another batch.

How to Sow

Coriander is straightforward to sow and the seeds are large enough to handle easily.

For direct sowing, make a shallow drill around 1cm deep and sow the seeds fairly thinly. Cover with soil, gently firm the surface and water if conditions are dry.

For pots, use a container with drainage holes and fill it with multipurpose compost. Sow the seeds over the surface, cover them lightly and water gently.

I like sowing coriander reasonably close together when I'm growing it mainly for young leaves. If you're growing plants on to produce seed, give them more room to develop.

Keep the soil or compost moist while the seeds germinate.

Coriander doesn't particularly enjoy being moved once it has developed a good root system, so direct sowing or starting it in the container where it's going to grow is usually the simplest approach.

Thinning and Growing On

Once the seedlings appear, thin them if they're badly overcrowded.

If you're growing coriander mainly for leaves, you don't need enormous gaps between every plant. Somewhere around 5–10cm apart is usually enough, and you can harvest some of the crowded seedlings as they grow.

For plants you're allowing to mature and produce flowers and seed, give them more room — around 20cm apart is useful.

Don't waste the thinnings. Once they're large enough, the young leaves and stems can go straight into the kitchen.

Keep weeds under control while the plants are small, taking a little care around the roots.

Coriander grows quickly when conditions suit it, so there isn't usually much growing-on work involved. When a plant begins stretching upwards and producing finer leaves, it's preparing to flower.

You can slow this down by keeping plants watered and reasonably cool, but eventually the plant is going to win that argument. That's why I always like to have another sowing coming along behind it.

Watering and Feeding

Coriander grows best when the soil stays reasonably moist.

You don't need to keep it soaking wet, but don't repeatedly allow plants to become completely dry either. Give them a proper watering when they need it rather than just wetting the surface.

Coriander growing in containers needs a little more attention because pots can dry out remarkably quickly.

In reasonable garden soil, coriander doesn't need much feeding. If you're growing it in fresh compost or reasonably fertile ground, I'd generally leave it alone.

Container plants that have been growing for a while may benefit from an occasional general-purpose liquid feed, but there's no need to overdo it.

If your aim is plenty of fresh leaves, steady growth is what matters. Coriander is a quick crop — I tend to sow another pot rather than spend too much time trying to revive an old, tired plant.

Harvesting

You can start harvesting coriander as soon as the plants have produced enough leaves to make picking worthwhile.

For young plants, snip off individual outer leaves and stems and leave the centre to continue growing. If you've sown fairly thickly, you can also harvest whole young plants to thin the crop.

Once plants start flowering, the leaves become finer and the flavour can change. At this point I usually let some plants carry on because the flowers are useful to insects and the seeds are worth harvesting.

For coriander seed, allow the flower heads to mature until the seeds have formed and begun turning brown. Cut the stems and finish drying them somewhere airy before storing the seed.

So don't think of a flowering coriander plant as a failure. You've just moved from harvesting the leaves to waiting for the seeds.

Common Problems

Bolting

Bolting is probably the biggest frustration when growing coriander. The plant suddenly stretches upwards and starts flowering instead of producing lots of leafy growth.

Hot weather and dry conditions can bring it on. Summer shade, regular watering and repeated small sowings will help keep you supplied with leaves.

Once a plant has properly decided to flower, I wouldn't spend too much time fighting it. Let it flower and start another sowing.

Poor Germination

Coriander normally germinates readily, but cold, very wet soil can slow things down.

For early crops, start seeds under cover or wait until outdoor conditions improve. Once you've sown, don't let the compost or soil completely dry out while you're waiting for the seedlings to appear.

Aphids

Aphids can occasionally gather around tender new growth and flower stems.

Small colonies can usually be washed or rubbed away. Once coriander flowers, you'll often find plenty of beneficial insects visiting the plants too.

Yellowing Leaves

A few older yellow leaves aren't usually anything to worry about. More widespread yellowing can be caused by waterlogged soil, exhausted compost or badly overcrowded plants.

Have a look at the growing conditions before automatically reaching for fertiliser.

Wilting in Hot Weather

Coriander doesn't do particularly well in the worst of the summer heat and can wilt quickly when the soil dries out.

Keep an eye on pots in particular, and move containers somewhere with a little afternoon shade during really hot spells if necessary.

Plants Flowering Too Soon

Sometimes coriander seems determined to flower almost as soon as you've started harvesting it. That's particularly common during summer and doesn't necessarily mean you've done anything wrong.

This is why I don't rely on one sowing. Sow a little every few weeks and let the older plants flower when they're ready. You'll have younger plants for leaves, flowers for insects and eventually seeds for the kitchen — which isn't a bad return from a packet of coriander seed.