Growing Kale Hydroponically: A Tower Garden Growing Guide

Starting Kale from Seed

Kale is easy to start from seed and usually germinates readily when conditions are right. Start the seeds in rockwool or your preferred hydroponic seed-starting media and keep them evenly moist while they germinate.

Once the seedlings have developed their first true leaves and have a healthy root system developing through the rockwool, they can be moved into the Tower Garden.

Want more help with germination and knowing when seedlings are ready for the Tower? Our Tower Garden Seeds & Seedlings Guide covers the entire process.

Where Should Kale Go in a Tower Garden?

Kale doesn't vine and doesn't require a support cage, so placement is fairly flexible. The bigger consideration is how large the variety will become.

A mature kale plant can spread considerably farther than a young seedling suggests. Give larger varieties enough room that they don't completely shade nearby lettuce, herbs or smaller greens.

Regular harvesting helps. Removing mature outer leaves keeps the plant productive while also preventing it from taking over quite as much space.

Light & Temperature for Kale

Kale is usually classified as a cool-season crop, and it certainly grows well in cooler temperatures. But that doesn't mean you have to stop growing it when summer arrives.

We grow kale year-round here in the Florida Keys, including through our hot summers. That's one of the reasons we're careful about making blanket statements about growing seasons. Your climate, the location of your Tower Garden, reservoir temperature, water management and the variety you're growing can all affect how a crop performs.

In hotter conditions, pay particular attention to the reservoir and your plants. Keeping the reservoir topped up, protecting it from excessive heat and adjusting nutrient strength when conditions call for it can help you continue growing through weather that isn't normally considered ideal for kale.

Growing Kale Indoors

Kale is also a good candidate for an indoor Tower Garden because it doesn't need pollination. The biggest requirement is providing enough light for sturdy, compact growth.

With Tower Garden LED grow lights, we generally run the lights for 14–16 hours per day, followed by a period of complete darkness. Keeping the lights approximately 6–8 inches from the tops of the plants is a useful starting point, adjusting them as the plants grow.

For more detail, see our Tower Garden Light Guide →

Water, Nutrients & pH for Kale

Kale doesn't need a special nutrient formula. It can grow in the same Tower Garden Mineral Blend solution as lettuce, herbs and many of the other crops in your Tower.

Our standard Tower Garden nutrient strength is 20 mL of Mineral Blend A and 20 mL of Mineral Blend B per gallon of water. For young seedlings, we normally begin at about half strength—10 mL of A and 10 mL of B per gallon—while they become established.

Keep the reservoir topped up and aim for a pH of approximately 5.5–6.5.

For more help with water quality, reservoir care, nutrients and pH, see our Tower Garden Water Guide and Tower Garden Nutrient Guide .

Caring for Kale as It Grows

Kale is relatively low maintenance once established. Most of your work is simply keeping up with harvesting and watching for changes in the plant.

• Harvest mature outer leaves regularly.
• Leave the center growing point intact so the plant keeps producing.
• Remove yellowing or damaged leaves.
• Make sure larger plants aren't blocking light from neighboring crops.
• Watch the undersides of leaves for early signs of pests.

You don't have to wait for a kale plant to become enormous before you begin harvesting. Picking leaves regularly is one of the advantages of growing kale—you can take what you need and let the plant continue producing.

Common Kale Pests & Problems

Kale belongs to the brassica family, so many of the insects that like broccoli, cabbage and cauliflower are equally happy to find your kale.

Outdoors, keep an eye out for chewing damage and inspect the undersides of leaves regularly. Caterpillars can do a surprising amount of damage before you notice them if you're only looking at the top of the plant. Aphids can also gather on new growth and underneath leaves.

Indoors, pest pressure may be lower, but it isn't impossible—especially if plants were previously outside or new plants are introduced into the growing area.

If you find insects, unusual leaf damage or signs of disease, our Tower Garden Pests & Diseases Guide can help you narrow down what you're seeing.

How to Harvest Kale

Kale is generally ready to start harvesting about 4–6 weeks after transplanting a seedling into your Tower Garden. You don't need to wait for the plant to reach its full size before you begin enjoying it.

One of the best things about kale is that you don't have to harvest the entire plant at once. Start with the larger outer leaves and work inward, leaving the smaller leaves and center growing point in place. The plant will continue producing new leaves from the center.

Regular harvesting also keeps the plant more manageable in a vertical garden and helps prevent large leaves from shading neighboring plants.

Is Kale a Good Crop for Tower Garden?

Absolutely. Kale is productive, doesn't require pollination and can be harvested repeatedly from the same plant. It also grows well alongside many of the other leafy greens and herbs commonly grown in Tower Garden.

For beginners, it's a forgiving crop, and for experienced growers, having fresh kale available for repeated harvests makes it an easy crop to keep in the rotation.

Although kale is usually described as a cool-season vegetable, our own experience growing it year-round in the Florida Keys shows just how adaptable it can be. Give it good light, manage the reservoir for your conditions and harvest regularly, and kale can be one of the most useful crops in your Tower Garden.