How to Grow Cilantro from Seed Hydroponically
You can grow cilantro from seed hydroponically with nothing more than a container, nutrient solution and a floating medium. The step-by-step Kratky method guide for cilantro covers the three setup steps. This post goes deeper into step three, planting the seeds, and into what happens in the first weeks.
What a cilantro seed is
A cilantro "seed" is really the dried fruit of the plant, and it holds two seeds inside a papery husk. Some growers lightly crush the husk before sowing so the seeds inside take up water more easily. Soaking the seeds in water overnight is another common trick. Neither is required, but both can help.
Set up the medium
- Prepare a clean container and mix the nutrient solution, as in the guide. See Kratky cilantro container: what size and type to use for choosing the container.
- Place the floating medium on or just above the solution, so it stays damp. The guide says to space the seeds evenly and make sure they have access to light.
- Scatter a few more seeds than you need. Not all will sprout.
Keep the seeds moist and cool
Seeds need constant moisture to germinate, which is easy in a Kratky setup because the medium sits against the solution. Cilantro prefers cooler conditions to hot ones, so avoid a spot that gets very warm. Germination often takes one to two weeks, and it can take longer.
Light after sprouting
Once the seeds sprout, give the seedlings light right away. Without it, they stretch and grow weak. At least six hours of sunlight a day, or grow lights, is the guide's recommendation. If the seedlings are already stretching, read leggy cilantro: causes and fixes.
Thin the seedlings
When several seedlings are crowded together, keep the strongest and snip the others at the base with scissors. Crowded plants compete for light and are more likely to grow thin and weak.
Feeding young plants
Seedlings need less nutrient than mature plants. Many growers start with a weaker solution than the label's full dose, then raise it as the plant grows. Follow your nutrient maker's directions and keep the pH between 6.0 and 6.8.
Choosing which seeds
Different varieties behave differently, especially when it comes to bolting. Our page on cilantro varieties compares Santo, Leisure, Calypso and Slow Bolt cilantro to help you pick.
What the first weeks look like
After the seeds sprout, you will see two thin, grassy seed leaves first. The lobed, lacy cilantro leaves appear next, and the plant starts to look like the cilantro you know. That is also the moment to check your light and your water level, because growth speeds up once the true leaves arrive.
Common questions
How long do cilantro seeds take to sprout?
Often one to two weeks, and sometimes longer. Cooler conditions and steady moisture help.
Can I plant coriander seeds from the spice aisle?
They are the same species, so they can sprout. Results can be uneven, though, and spice seeds may have been heat-treated. Seeds sold for planting are more reliable.
Do cilantro seeds need light to sprout?
Not to germinate, but the seedlings need light as soon as they appear. Without it they stretch and grow weak.