People keep asking “What are we doing wrong?” in growing coriander (or cilantro*). I hope this will be helpful.
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If you bought plants or sowed seed in May, when you put the rest of your garden in – tomatoes, beans, corn, basil, zucchini – it was green and leafy for a while. Now, when your tomatoes are red, your coriander has turned, first thin and feathery-looking, and then tall, coarse and leggy, with white flowers and then little green seed capsules. You’ve tried watering it and cutting it back, but it’s getting yellower and yellower. Soon it will be brown and dead looking. (The rest of your garden is doing great.)
It’s not anything you’re doing wrong. All your other plants are warm-weather crops. You can’t even set them out until danger of frost is past. It’s when you’re doing it. Cilantro, on the other hand, is what we call a “winter annual.” It may sprout in very cool weather, and live through all but the coldest. Like the weeds that were already green and thriving when you started your garden, and are now going to seed all over the place. Many weeds are winter annuals. As soon as weather is warm and drier, they go to seed. So does Cilantro.
So what about your salsa? (Or grilled fish, or tandoori chicken, or Thai scallops?)
One answer is to enjoy coriander when it’s in season. If you can your own tomatoes, and let your coriander go to seed now, in the dead of Winter you can go out and get some nice green leaves from under a light mulch, and enjoy salsa that you can’t tell from fresh. You can sow cilantro in November, February, March or April, and have it stay green and leafy for weeks longer than if you sow it in warm weather.
But your tomatoes are red and juicy now! Okay. There are a few simple steps for growing coriander throughout the gardening season.
First, forget about buying plants. Why pay a dollar for 4 seedlings of an annual, when you can get a packet of 100 seeds for a little more? Then, nurseries offer cilantro seedlings with all their other bedding plants, April-June. Once yours have bolted, theirs have too! So you’ll have trouble finding replacements. Another problem is that coriander has a long fibrous taproot, like carrots, to which it’s related. Unless you transplant ver-ree carefully, disturbing the root sends the plant a signal that it’s been “pulled up.” Cool weather or not, it may then bolt (set seed) as a survival mechanism. It’s best just to sow it where it’s going to grow.
If it’s been a hot and dry year, keeping fresh cilantro on hand has required special attention. Here are some of the tricks that have worked for me.
1. Where? It doesn’t require particularly rich soil, but that long taproot grows better where the ground is well-tilled. Pick a row in your vegetable garden where the soil is deep and loose, maybe where one of your Spring crops has quit for the summer – like lettuce. Wood ash is very helpful in keeping the soil light: dig in a cupful every foot or so. Divide the row into sections and sow a dozen seeds about every three weeks.
2. Shade. If you have a garden section that’s near trees, use that for cilantro. If it gets morning sun but is shaded when the day gets hot, it will grow – not as thick as in full sun, but it won’t bolt as soon either.
3. Repeat sowings. Don’t wait for bolting to start before sowing more seed. When the seedlings in one section have sprouted, sow the next section.
4. Keep soil as cool and damp as possible. Try this: after cultivating thoroughly, soak the ground to a depth of a few inches, late in the evening. The water will cause the soil to cool overnight. In the early morning, apply a thick but loose layer of dried grass clippings over the cool damp soil. Then sow the seeds right into this mulch. Keep the mulch damp till seedlings emerge. (Don’t use fresh grass clippings, they’ll compact too much).
5. Thin. Crowded plants bolt faster than well spaced ones (another survival tactic). As soon as seedlings are large enough to handle, pull any one that is growing right next to another. You’ll find many close “pairs” of seedlings. That’s because the “seeds” are actually seed capsules with two seeds in each. You’ll wind up with a nice handful of delicate-flavored ”baby cilantro,” a trendy restaurant ingredient!
6. Pull whole plants instead of cutting off leaves. It will allow more room for the remainder to grow. Plus, cutting off leaves may – you guessed it! Trigger the plant to bolt!
*Just another point we can clarify while we’re at it. Books keep saying “The fresh leaves are Cilantro and the seeds are Coriander.” That’s nonsense. Cilantro is simply the Spanish word for coriander. Leaves and seeds both are botanically Coriandrum sativum, from which the words coriander and cilantro are derived. The leaves were rarely, if ever, used in the US till widespread interest in Hispanic cuisines got started in the 1980’s. So we got to know leaf coriander under the name by which it was known to Hispanic cooks. In Spanish-speaking countries, the seed is also called cilantro. Q.E.D.