If there is one herb that often catches me off guard more than any other, it’s cilantro (or coriander, depending on where you are in the world).
You can plant it with the best of intentions, giving it your best soil, and water it diligently, and within weeks it can grow quickly into a spindly stalk of white flowers, leaving you with very little to harvest for your carrot and coriander soup!
Cilantro bolts (grows flowers and develops seeds) because of some specific identifiable triggers, and once we understand what the triggers are, we can work around them much more easily than most of the cilantro articles and guides that I have read.
I have personally made lots of mistakes when growing cilantro, but learned from each one! Here’s my personal experience…
What Bolting Actually Is (And Why Cilantro Does It So Aggressively)
So, bolting is just the process by which the cilantro transitions to vegetative growth (growing its lovely leaves) to ensure its survival by growing flowers and then setting seed. Cilantro makes this transition faster and is more reactive than any other herb!
Why? I did the research, and it’s to do with climate. Cilantro is a cool-season crop native to areas where growing windows are very short. Therefore, it has to complete its entire life cycle very quickly, whilst the conditions signal that there is warmth or stress coming, so it produces seeds before the season ends.
Once we understand this, we can understand that every bolting trigger is essentially the cilantro detecting an environmental cue that the growing season is closing, so set seed now!
Once I understood this, it reframed everything. You’re not trying to fight the plant. What we need to do is convince the plant that the growing window isn’t closing just yet.
The Grocery Store Trap (And Why Repotting Causes Immediate Bolting)
We have all done this! You grab a lush, beautifully dense cilantro from the supermarket and bring it home to carefully untangle its root ball and plant it into my best premium soil.
Within a week, rather than bushy leaves, it shoots upwards into a single stalk of white flowers.
It’s really confusing because it seems like you did everything right.
From research, I found out what actually happens. The supermarket herbs are grown hydroponically under optimal and intense conditions, with multiple cilantro plants crammed into a single pot.
The root systems of cilantro are very sensitive and have a long taproot that doesn’t respond well to being disturbed.
When you disturb this tap root during your repotting, even if you do it carefully, you send a stress signal through the plant.
How does it respond to this trigger? By panic bolting! An emergency reproductive response to what it perceives to be a survival threat.
Cilantro’s sensitivity to root disruption is also why I find it better to direct sow the seeds rather than transplant them.
Starting seeds in a small pot, then moving them, also has the same sorts of risk.
Therefore, if you are starting from seed, I would recommend sowing directly into the container or bed where you want the cilantro to grow and do not move it! This change eliminates one of the most common triggers of bolting altogether.
My Biggest Mistake: Treating Cilantro Like a Summer Herb
Very early in my gardening years, I treated my cilantro like basil and planted it in the sunniest, warmest spot in the garden or windowsill during June, and it bolted before it reached even 6 inches tall.
Here was my error…treat a cool-season crop like a tropical annual!
Our cilantro plants do not want maximum summer sun like basil does, but it wants the moderate temperatures of early Spring and Fall, between 50°F and 75°F (10–24°C), and once the temperatures exceed 80°F (27°C) consistently, then bolting becomes inevitable, no matter what you do, as temperature increases are a bolting trigger.
I learned that timing your planting is the best way to prevent bolting.
- Planting in the Spring…Sow the cilantro seeds as early as your last frost date allows. Cilantro tolerates a light frost in my experience and thrives in the cool weeks of early spring before summer heat arrives and causes it to bolt.
- Planting it in the Fall…Here’s what works for me…a second sowing of cilantro seeds in late summer for a fall harvest is usually more productive than a summer planting, as the cooling temperatures work in your favour rather than against you
- Succession sowing…Rather than one large planting, I sow small amounts every two to three weeks from early spring, usually in March, so that when one batch bolts, the next is ready
The Microclimate Trick That Extends Your Harvest
If you want to grow cilantro throughout the warmer months, then I found the answer isn’t just to plant it in the shade, but from my own experience, it is far more nuanced than that.
Plant your cilantro on the northeast side of taller crops such as tomatoes, kale, or anything else that sort of a similar height. This way, as the summer sun gets high and hotter, the larger plants can cast a moving shadow over the cilantro during the most intense hours of the afternoon sun. The cilantro effectively experiences a cooler and shorter day during the time period that is most likely to trigger bolting, whilst still getting enough morning light for healthy growth.
I have experimented with this approach and have extended harvests by several weeks. It is the closest thing I have tried to trick the cilantro into thinking it’s still spring and time to grow its leaves, rather than bolt.
The Early Warning Sign Nobody Tells You About
Most of the articles I have read online tell you to watch for flowers as a sign that bolting has begun. By then, you have already missed the growing window as the bolt starts the weeks before the white petals appear, and the plant tells you it’s coming if you know what to look for.
Cilantro produces two visually distinct types of leaves across its life cycle.
The juvenile leaves (which are the tastiest and the leaves you want) are broad, flat and more deeply serrated, and in my opinion resemble flat leaf parsley.
When the cilantro begins to prep for bolting, the newer growth that emerges from the centre shifts noticeably too, and the leaves become finer, feathery and rather dill-like than the broad flat leaves.
The moment you see the feathery fronds appearing at the centre of the cilantro, the clocks ticking!
The flavour of the leaves can deteriorate from this point. The leaves become bitter and even soapy as the cilantro redirects its energy from leaf growth to growing seeds.
In this scenario, I would recommend harvesting every remaining broad leaf immediately.
I have found that if you catch the transition early enough and snip the plant back hard, even removing the central stem where the feathery growing is emerging, then you can sometimes delay the bolting by a week or two.
This is not guaranteed, but I have found it is worth trying before the flower stalk develops fully.
When It Bolts Anyway: The Green Seed Pivot
As we discussed, even with perfect management, the cilantro always bolts eventually. What most gardeners do at this point is pull p the cilantro and start again. However, there is a better approach which turns it into something useful.
After your cilantro flowers, it produces seeds, and more people know these as dried coriander seeds, which are a spice.
They are crunchy, very citrusy and complex with a flavour profile that bears no resemblance to the dried spice.
I like to use them in Thai curry pastes and pickled with vegetables, and add fresh to salads and salsas.
So when your cilantro bolts, then let it run to seed and watch the seeds as they develop, and they start green and firm before drying to a pale brown of the spice we all know and use.
I would recommend that you harvest a portion while it’s green and taste one. The flavour is surprising enough that most people who try it actually start deliberately letting some of their cilantro bolt just for this.
Also, leave a bolted cilantro to go to seed, give you a free seed supply for your next year’s sowing, and I have found that cilantro self-seeds quite readily in many climates, meaning a bolted plant can effectively plant next season’s crop for you!
The Short Version
Cilantro bolts because of heat, root disturbance, and stress, which trigger the response to grow seeds.
In my experience, the most effective interventions are timing (sowing in spring and Fall rather than in Summer) direct sowing to protect the tap root and good positions to create afternoon shade.
And when it bolts, just harvest the edible green seeds. In my opinion, they are one of the most underrated ingredients in the garden.
Have you found a way to keep cilantro from bolting that works for your climate? Share it in the comments, I’d genuinely love to know.