Growing Hydroponic Watercress

 Watercress plant with flowers

Watercress is a semi-aquatic species of plant, making it perfect for growing in hydroponic systems.  It’s super easy to grow in hydroponics, and it happens to be extremely healthy as well.  In fact, the CDC recently stated that watercress is the most nutrient dense food you can eat!  Watercress has super high values of vitamin K, and contains significant amounts of vitamin A, vitamin C, vitamin B6, calcium, riboflavin, and manganese.  The leaves, stalks and flowers of watercress are all edible. 

Related to mustard greens, radish and wasabi, watercress is known for a peppery or even spicey flavor that some say is reminiscent of horse radish, but with less of a kick.  They make a wonderful addition to salads, sandwiches, soups, stir fries, green juices, and smoothies.  You may be able to use larger watercress leaves that grow up to 6 inches in diameter to make stuffed vegetable leaves.

Watercress’ natural environment is marshlands, streams and slow-moving rivers.  Because of this, the stalks are hollow to allow the leaves to float on the surface of the water.  The leaves generally grow to 3-6 inches long.

Whiteflies and spider mites are known as common pests for watercress, so keep an eye out and consider combining 1 tablespoon of non-toxic or organic dish soap with 1 quart of water, then spraying your leaves at the first sign of problems.  More on this can be found here.

Hydroponic Watercress
Germination Light EC Range pH Range: Time to Harvest
Easy 12-16 hours 0.4-1.8 6.5-7.0 4-6 weeks
Nutrient and Health Info - Watercress has super high values of vitamin K, and contains significant amounts of vitamin A, vitamin C, vitamin B6, calcium, riboflavin, and manganese.  The CDC says its the most nutrient dense food you can eat!
Tips & Tricks - While easy to grow, watercress may attract whiteflies and spider mites. Read above for more information.



Watercress typically grows along cool streams and rivers, so it will love being germinated directly in your iHarvest® or uHarvest® hydroponic system.  Germination will generally require 7-14 days.


Watercress will survive well under the low light conditions it experiences in shaded streams and rivers but will flourish more quickly with 14-16 hours of light per day.

EC Range:

Watercress typical absorbs many of its nutrients from water or shorelines, and has adapted well to grow in a variety of more or less nutrient rich environments.  Because of this, it is suitable to use a relatively wide range of EC’s when growing watercress. Any EC between 0.4 – 1.8 will do the trick.  However, nutrient levels on the upper end of that range are likely to result in faster growth.

pH Range:

Keep your pH range between 6.5 – 7.0 for great results!


The IGWorks® Green Machine nutrients are ideal for watercress.  There is no need to combine or switch your nutrients to our Flower Power nutrients in order to encourage the edible flowers to grow, although you will see more aggressive flower growth if you do.  Personally, I grow watercress much more for the greens than I do for the flowers. 


Time to Harvest:

Plan to begin harvesting leaves and stems in 6-8 weeks.

Pruning and Harvesting:

You will be using the cut and come again method of harvesting with watercress.  You can harvest from the base of the edible stems, and new shoots will emerge.  Of course, try to refrain from harvesting too much all at once, so that the plant can photosynthesize efficiently and constantly supply you with fresh greens.


When you think of super healthy, easy to grow greens, I hope that you will think about watercress.  The leaves are packed with vitamins and minerals!  The peppery, wasabi-like flavor is also a wonderful addition to green juices, smoothies, salads and more.

Check Out Our Watercress Recipes!

Let’s grow together!