Hydroponic cilantro
Kratky Cilantro: Growing Cilantro in a Jar, Step by Step
Cilantro is one of the faster herbs to grow with the Kratky method, and one of the quickest to quit. It likes a cool room and bright light, and it bolts (runs to flower) as soon as it gets warm. This guide covers the jar setup, the light and temperature it needs, and how to keep a steady supply by starting a new jar every few weeks.
Step by step
Kratky Cilantro in Five Steps
Set Up the Jar
A quart mason jar or a small tub with a lid works. Fill it with hydroponic nutrient solution up to the bottom of the net pot, so the base of the pot just touches the liquid.
Sow the Seeds
Fill a net pot with rockwool or clay pebbles and sow 5 to 8 seeds about a quarter inch deep. Each cilantro "seed" is a husk holding two seeds; cracking it gently first can speed germination.
Give It Light
12 to 16 hours a day under a grow light, or the brightest window you have.
Keep It Cool
50°F to 75°F. Much warmer than that and cilantro bolts within weeks.
Harvest at 4 to 6 Inches
Cut the outer leaves and let the center keep growing.
Benefits
Why Kratky Suits Cilantro
No Pump, No Air Stone
You fill the jar once. As the plants drink, the level drops and the upper roots grow into the air gap, where they get their oxygen. Nothing needs power.
One Fill, Most of a Crop
Cilantro lives fast, so one fill of solution usually lasts most of its useful life. If the level drops below the roots early, top it up part way, not to the brim.
Fits a Windowsill
A quart jar takes up less room than a pot of soil and nothing drips, so a few jars fit on a sill or a shelf under one light.
Easy to Stagger
Jars are cheap to start, so sowing a new one every 3 to 4 weeks keeps fresh leaves coming while the older jar bolts.
Light
How Much Light Cilantro Needs
Cilantro needs 12 to 16 hours of light a day. A winter window rarely gives that much, so most indoor growers use a basic LED grow light. Set it a few inches above the leaves and raise it as the plants grow. LEDs run cool, which matters for an herb that bolts in heat; an old-style bulb close to the jar can warm the plants enough to push them into flower.
Signs the Light Is Wrong
Too little light shows first: long, pale stems that lean toward the window and flop over. Move the light closer or add hours. Too much shows as bleached or crisp leaf edges nearest the light; raise it an inch or two. A plug-in timer keeps the hours the same every day, and turning a windowsill jar a quarter turn every few days keeps the plants upright.
12-16hours of light
Temperature
Keeping Cilantro Cool
Keep the room between 50°F and 75°F (10°C to 24°C). Heat is the main reason cilantro bolts: the center stem shoots up, flower buds form and the new leaves turn thin, feathery and bitter. Once that starts it doesn't reverse. Keep jars away from heaters, ovens and hot afternoon glass. In summer, a cooler room or a spot with moving air helps; a warm windowsill in July will bolt cilantro faster than anything else. The solution matters too: a jar sitting in full sun can heat the roots, so a jar sleeve or an opaque container helps.
50-75°F10-24°C
Harvest
When and How to Cut Cilantro
Start cutting when the plants are 4 to 6 inches tall. Take the outer stems near the base with scissors and leave the small center leaves to keep growing. Take no more than a third of the plant at a time, and give it a week or so before the next cut. Regular cutting slows bolting a little, but it won't stop it, which is why a new jar every 3 to 4 weeks is the easiest way to always have some.
After the harvest
Timing, Storing and Keeping Cilantro
Timing Your Cilantro Harvest
Pick in the morning, when the leaves are crisp. Watch for a tall center stem or flower buds: once you see them, harvest the rest of the jar, because the leaves only get thinner from there. If you'd like coriander seed, let one jar flower and dry on the plant instead.
Storing Freshly Harvested Cilantro
Stand the stems in a glass with an inch of water, put a bag loosely over the top and keep it in the fridge. Change the water every couple of days and it keeps about a week. For a small handful, a damp paper towel in a bag works too.
Extending Cilantro's Shelf Life
Freeze it. Wash and dry the leaves, chop them and pack them into ice cube trays topped with water or olive oil, then drop a cube into soups, salsa or curry. Dried cilantro loses most of its flavor, so freezing is the better way to keep a big harvest.
Go deeper
More on Growing Cilantro
This page is the short version. Our sister site Kratky Cilantro covers cilantro in depth.
- Kratky Cilantro: the full guide to growing cilantro with the Kratky method
- Growing cilantro from seed: sowing and germination
- Stopping cilantro from bolting: heat, light and timing
- Storing fresh cilantro: keeping the harvest fresh longer
Related Kratky Herbs
Cilantro is fast and short-lived, so start a new jar every few weeks. Parsley and chives are slower herbs that keep going.