How to Sow Coriander (Cilantro) Direct and Get an Even Stand

Sow where the plant is going to stand

Coriander, sold as cilantro wherever the leaf is the point, puts a slim taproot straight down within ten days of germinating. Lift it after that and the tip breaks. The plant survives the move but reads the check as a season ending, and it runs to flower weeks earlier than a direct sown plant beside it.

This is why supermarket pots and garden center plugs bolt so fast in the garden. They were grown warm and crowded, their roots are already circling, and the transplant is the final trigger. Sow into the ground or straight into the final container instead. Two minutes of sowing saves you a crop that flowers before you have cut anything from it.

1. If you must raise plants under cover, use deep cells In a cold spring, sow into cells at least three inches (8 cm) deep, three or four seeds to a cell, and plant the whole cell out as one clump within three weeks. Never transplant individual seedlings and never split the rootball.
2. Sow into the final pot For containers, fill the pot you intend to keep it in and sow into that. Moving a seedling from a small pot into a large one costs you two weeks of leaf just as surely as planting out from a plug.
3. Loosen the soil deeper than you think Fork the bed to a spade's depth. A taproot that meets a compacted pan at four inches (10 cm) forks, the plant stays small, and it bolts on the first warm week.

A plant that has been moved shows it: the lower leaves stay broad and flat, but the center pushes up a thin, ferny shoot far sooner than it should. That shoot is the flower stem starting.

Each seed is a husk holding two seeds

What you sow is not a seed but a dry, ribbed fruit with two seeds inside it. That is why coriander germinates raggedly: the halves take up water at different rates, and one may come up a week behind the other. It also means a packet holds roughly twice as many plants as it looks like.

Cracking the husk evens things up. Roll the seed under gentle pressure on a hard surface until you hear the papery shells split, then soak the pieces in cool water for a day. Soaked seed sown into damp soil comes up in seven to ten days instead of the fourteen to twenty a dry, unsplit husk takes.

1. Split, do not crush Press with the flat of a rolling pin or the heel of your hand. You want the husk in two halves with the seed inside intact. Anything reduced to powder is wasted.
2. Soak for 24 to 48 hours Cool water, changed once. Longer than two days and the seed starts to sour. Sow it damp, straight from the water, and do not let it dry again.
3. Sow thickly and thin later Expect around 60 to 70 per cent of split seed to come up. Sowing at half inch (1 cm) spacing along the row and thinning gives a better stand than trying to space single seeds accurately.

Depth, spacing and soil temperature

Coriander germinates over a wide range but has a clear preference. Below 50F (10C) it simply sits, and above 77F (25C) germination drops away and the seedlings that do appear bolt almost immediately. The sweet spot is a soil around 59 to 68F (15 to 20C), which is why the two reliable sowing seasons are spring and late summer, not the middle of summer.

A shallow window box will grow you one cutting and then bolt. The depth of soil under the plant does more for how long it stays in leaf than the width of the container does.

Sow again every two or three weeks

This is the whole trick with coriander. A single sowing gives you three or four weeks of cutting and then flowers, no matter what you do. Growers who always seem to have leaf are not growing it better, they are sowing a short row every fortnight and pulling the old one out.

Keep each sowing small. A row two feet (60 cm) long, or a third of a trough, is enough for a household. Sow the next one when the previous sowing has its first true leaves, and you will never see a gap.

Where winters are mild, a sowing made as the days shorten sits small through the cold and then grows away fast in early spring, giving you leaf a month before a spring sowing does.

Thinning, and what to write down

Thin in two passes rather than one. Take the crowded seedlings out at two true leaves, leaving them about two inches (5 cm) apart, then thin again a fortnight later to the final spacing. Snip the unwanted ones at soil level with scissors instead of pulling, so you do not disturb the taproot of the one you are keeping. Every thinning is edible.

Coriander rewards record keeping more than most herbs because the useful information is all about timing. Note the date you sowed each row, the date the first true leaves appeared, and the date you first saw a flower stem push up from the center. After one season those three dates tell you exactly how many weeks a sowing lasts in your garden, and therefore how far apart to space the next year's sowings.

1. Log the position of each sowing Sketch which end of the bed each successional row went into. Coriander self sows freely, and next spring you will want to know whether a patch of seedlings is a volunteer or the row you sowed.
2. Note the weather in the bolting week Write down the highest temperature in the week a row ran to flower. That number, more than any calendar date, tells you when to move sowings into shade.
3. Record which sowing tasted best Leaf from a cool autumn sowing is broader and milder than leaf cut in a hot spell. Noting it stops you blaming the seed for a flavor that came from the heat.