Bolting Cilantro - Why Does Cilantro Bolt And How To Stop It

Cilantro (Coriandrum sativum) is used in a great many different dishes, particularly in Mexican and Asian cuisine. Despite the growing popularity for this herb in cooking, many gardeners choose not to grow it, primarily because it seems to bolt, or go to seed so easily.

Cilantro Growing Conditions

The most important thing to remember when growing cilantro is that it doesn’t like hot weather. Cilantro growing in soil that reaches 75 F (24 C) will bolt and go to seed. The Ideal cilantro growing conditions are cool but sunny. You should be growing cilantro where it will get early morning or late afternoon sun, but be well-shaded during the hottest part of the day.

Why Does Cilantro Bolt?

As an amazing survival mechanism, cilantro will bolt when temperatures heat up in late spring or summer, quickly producing stalks of little white flowers and seeds to ensure its own reproduction. The plant is unable to tolerate the heat, and so proceeds to do the most logical thing.

How to Keep Cilantro from Bolting

It is impossible to completely forestall bolting. It’s a fact of nature that cilantro will react to heat this way. However, there are some things you can do to delay bolting or to work around it to your advantage:

Plant cilantro in the shoulder seasons

Cilantro does best in spring and fall when the weather is cooler. Plant in early spring and again in late summer to get two harvests under the best conditions.

Harvest regularly

Remove leaves regularly from your cilantro plants. This will help to remove immature flowers before they have fully formed and slow down the bolting process a little bit.

Use mulch

It is the temperature of the soil that pushes cilantro to bolt. Keep the soil cooler and help it retain moisture by mulching around the plants.

Water regularly and find shade

Once you’re into the hot part of the summer, you can extend the life of your cilantro by keeping it as moist and cool as possible. Water daily and move pots of cilantro to shadier areas of the garden during the hottest afternoon hours.

Prune

Though you can't completely stop cilantro from bolting, you can delay it by cutting back immature flower stalks when they first appear.

Succession plant cilantro

Ultimately, gardeners must accept that each cilantro plant has a short season. To get around this and to continue to harvest throughout the growing season, practice succession planting. Plant seeds every couple of weeks. When one set of cilantro plantings is bolting, the next will be ready to harvest.

Look for slow bolt cilantro

Slow bolting cilantro varieties tolerate heat a little better, and are slower to bolt in the summer heat. Some varieties to look for include Slow Bolt, Calypso, and Leisure.

Can You Eat Flowering Cilantro?

There is nothing about cilantro flowering that makes the plant inedible or toxic, but the leaves do lose much of their flavor. The plant will also grow smaller and leaves will take on a lacy, fern-like appearance.

What to Do When Cilantro Goes to Seed

Cilantro’s delicate white flowers are a happy development for pollinators, and this is the stage when the plant begins to produce its delicious seeds. But as the plant starts to use its energy to blossom and make seeds, it shrinks and the flavor in the leaves begin to fade. Cilantro leaves at this stage, while edible, won’t have the same punch of flavor as when the plant is young. When the plant bolts, the depleted leaves are no longer worth harvesting.

Cilantro Seeds

When it has bolted, cilantro gives us an opportunity to harvest the seeds and propagate the plant. If your cilantro seeds look familiar, that's because they are also known as the spice coriander, which is a common addition to many cuisines.

The seeds come in pairs encased in a hard, round husk. When the husk turns brown the seeds are ready to harvest. Just roll the seeds in your hand to remove the outer hull. To prepare coriander seeds for cooking, dry them in the oven on a low heat until they’re crumbly, then grind them into a powder. To prepare them for planting, dry them naturally and prepare them for germination.

How to Plant Cilantro

Before you plant them in the ground, prepare the cilantro seeds to increase the chances that they will germinate. After removing them from the husk, soak the cilantro seeds in water for 24 to 48 hours. Remove them from the water and allow them to dry.

Once you have prepared the cilantro seeds, you can either start cilantro indoors or outdoors. If you’re starting the seeds indoors, you’ll be transplanting it to the outdoors later on.

Here’s how to direct-sow the seeds in your garden. Place seeds in the garden bed and cover them with about a 1/4-inch (6mm) layer of soil. Keep them consistently watered until they sprout. Let the seedlings grow until they’re at least 2 inches (5 cm) tall. At this time, thin the plants to be about 3 to 4 inches (7.5 to 10 cm) apart. It’s good to grow cilantro in crowded conditions because the leaves will shade the roots and help to keep the plants from bolting in hot weather.

If you’re transplanting cilantro seedlings into your garden, wait until they have developed a couple sets of true leaves. Dig holes 3 to 4 inches (7.5 to 10 cm) apart and place the plants in them. Water thoroughly after transplanting.

Additional Tips for Growing Cilantro

Even with ideal growing conditions, cilantro is a short-lived herb. Taking the time to prune cilantro frequently will help delay bolting and prolong your harvest time, but no matter how much you prune cilantro, it will still eventually bolt. Plant new seeds about every six weeks to keep a steady supply throughout the growing season.

Cilantro will also reseed itself in many zones. Once the cilantro plant bolts, if you let it go to seed and it will likely grow again for you next year, or collect the cilantro seeds and use them as coriander in your cooking.

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