Growing Hydroponic Kale

Hydroponic Kale
Difficulty Light EC Range pH Range: Time to Harvest
Easy 16hours 1.6 -2.5 5.5 -6.8 4 weeks
Nutrient and Health Info -High in vitamins A, K, C. It's a great anti-inflammatory food with healthy amounts of fiber and calcium.
Tips & Tricks - Grows well with chives, beans, peppers and spinach, swiss chard and bok choy. Grows incredibly fast once mature. Should be harvested often. Use the cut and come again harvest method you will have lots of Kale for several months or longer.


Kale is known for its earthy and often bitter flavor, in addition to its incredible health benefits discussed below.  Like other leafy greens with strong flavors (i.e. arugula) younger kale leaves will not taste as strong, and will also have softer and thinner leaves that are more enjoyable to eat raw.  Kale also has 10-20 different varieties, with sometimes unique flavors, such as Red Russian Kale, which is known to be a sweeter variety.

Kale’s nutritional value makes it a favorite of many gardeners.  It’s a great deal healthier than lettuce.  Per calorie, kale has more iron than beef and more calcium than milk.  A single cup of raw kale is said to have over 200% of your daily value of Vitamin A, nearly 700% DV of Vitamin K and 134% of your Vitamin C.  It’s also a great source of antioxidants.  Finally, kale’s quite low in fat, but a large portion of the fat that it does have comes in the form omega-3 fatty acids (the same great stuff that you get from eating fish).


Kale will typically grows well from seed.  Consider using our Seedling Starter Kit, or simply using the paper towel method if you have any troubles. But, you shouldn’t have trouble sowing your kale seeds directly in the iHarvest® or uHarvest®.  Your seeds will likely be a little slower to develop seedlings, but you will still have a high rate of success.


Kale is a very fast grower (especially with hydroponics), so giving it 16 hours of light a day will support its energy needs.  And, because the iHarvest® and uHarvest® use high efficiency LED lights, it will not lead to a drain on your energy bills.

EC Range:

Your iHarvest® comes with an EC (electrical conductivity) tester to measure the amount of the nutrients in your water solution.  When growing kale, keep your EC between 1.6 to 2.5.  This means that your kale will grow well with chives, beans, peppers and spinach, for example.

pH Range:

Adjusting your pH allows your plants to absorb the nutrients they need as efficiently as possible.  Keep your pH between 5.5-6.8 for optimal growth of kale.


Kale is leafy plant that you don’t want to flower and does not fruit, so it’s going to grow great with an all-around hydroponic growing solution for greens.  Mix your Green Machine nutrients in the reservoir until your EC is between the range of 1.6-2.5.  Remember to mix thoroughly, either by stirring your reservoir or letting the pump run for 15-minutes after adding nutrients, before measuring to determine if the EC is just right for your kale to thrive.

Pruning and Harvesting:

Trim the mature outer leaves, while allowing immature leaves to grow larger quickly.  Remember, harvesting younger leaves will reduce the strong flavors of kale that some prefer to stay away from. 

Kale will grow incredibly quickly when it matures, so don’t overplant unless you use lots of it often.  It can also take over, and prevent other plants from getting the light they need to grow, so harvest frequently.

Time to Harvest:

Kale is an aggressive grower that you will be able to begin harvesting within 4 weeks of planting. Kale is very slow to bolt, and is known for not bolting until the second year of its life, and even then often takes a change to higher indoor temperatures to make it happen.  Unless you want to let your kale to go to seed, you should remove the flowers and consider removing the entire plant if it begins to taste less to your liking.


Kale’s many health benefits make it a favorite of many to grow in the iHarvest.  Planting kale in only a few spots will go a long way, as it’s such an aggressive grower. Harvesting leaves while they are young will mean that they will taste less bitter and earthy, which some prefer. Mix them into a salad, use them soups, sauté them or use them to make kale chips in the oven.  These dynamic greens have many uses to go along with their many health benefits.

Check Out Our Kale Recipes!

Let's grow together!