Kale (Brassica oleracea) is a hardy vegetable belonging to the Brassica genus under the mustard family. Although broccoli and cauliflower belong to this family, kale most resembles its close relative, cabbage.
Frost-tolerant, kale is a great leafy green to grow in your home garden. Sow seeds from fall to early spring to avoid the summer heat which turns the leaves bitter.
While kale does well outdoors, growing kale in containers from seed indoors is a great way to keep a fresh source of greens year-round. As long as you have adequate sunlight and provide enough space and water, you’ll be able to reap the benefits of kale’s long growing season.
Why grow kale?
- Nutritious: Rich in nutrients, vitamins, and dietary fiber, kale is a super-healthy leafy green. Just one cup of raw kale contains:
- Vitamin A: 206 percent DV
- Vitamin C: 134 percent DV
- Vitamin K: 684 percent DV
- Easy to harvest: Kale is a biennial vegetable meaning you can harvest leaves and it will grow back.
- Easy to grow: A hardy plant that can withstand frost, kale is easy to grow from seed indoors, or directly sown in your outdoor garden.
Kale growing conditions and care
When growing vegetables indoors, it’s important they still receive the proper amount of sunlight (either naturally or artificially). Kale likes full to partial sun, generally around 6 to 8 hours of sunlight a day.
More sun encourages the production of its yellow flowers. If you’re placing your kale container outside and you live in a very dry, warm climate, be sure to give it some shade in the hot afternoon hours. Too much heat and sun turns kale leaves bitter.
Kale prefers a neutral soil with a pH of 6.0 to 7.5. Like collards, kale likes loamy, well-drained soil rich in organic matter—so don’t skimp out on the organic compost. You can add more compost every two months or so. If your soil is rich in organic matter, you might not need to apply any fertilizer.
When it comes to watering kale, slow and steady wins the race. Kale doesn’t need a lot of water, just ensure soil is kept moist for even growth. When growing kale in containers, keep a watchful eye on moisture levels as container gardens tend to dry out more quickly.
Varieties of kale to plant indoors
Kale has a large variety of cultivars to choose from, with varying colors ranging from all shades of green to lavender. Leaves can be curly, flat, bumpy, or a hybrid. Some kale varieties are planted purely for ornamental purposes.
Keep in mind that when selecting a kale cultivar, it’s best to stick with compact or dwarf varieties that produce a high yield when you’re growing indoors. This helps you get the best ‘bang for your buck’ so to speak when dealing with limited space.
Here’s a few suitable indoor kale varieties to consider:
- Dwarf Blue Curled: Also known as Scotch kale, Blue Scotch Curled, or simply as Vates kale, this is perhaps the type most people are familiar with as it’s commonly found in grocery stores. Characterized by its dark-green, frilly leaves and rich, robust flavor, it’s great for adding to smoothies, soups, and making crispy kale chips. Its compact-size makes it ideal for indoor container gardening. It’s also cool-hardy and slow to bolt in hot weather.
- Lacinato: Also known as Dinosaur kale or Tuscan kale, this kale variety has narrow leaves with slight dimples. With a more delicate flavor profile than Scotch kale, you’ll like to eat this variety fresh—great for salads.
- Dwarf Green Curled: Also known as Bloomsdale, Jamaica, or Dwarf Curled Scotch kale. With tightly curled, yellow-green leaves, this is an heirloom variety that remains compact, perfect for container gardening. It’s also cold-resistant, good for winter harvesting.
- Starbor: With dark, bluish-green, curled leaves this is a variety that’s great indoors as it’s compact and high-yielding—each stem carries tightly packed leaves.
Check out a list of over 50 kale varieties here.
If you’re planning on planting kale with other vegetables in a container, here are a few good kale companion plants:
Avoid planting kale near tomatoes, potatoes, beans, eggplant, and peppers.
Growing kale in containers indoors step-by-step
Make sure you select a sunny area that gets around 6-8 hours of sunlight a day and use an adequate-sized pot (at least 12 inches wide and deep).
Once you’ve selected your kale seeds and gathered a few basic gardening supplies, you’re ready to start!
- Quality kale seeds
- Plant container(s) with drainage, at least 12 inches wide and deep
- Quality potting soil and organic compost
- Clear plastic bag
- Nitrogen-rich organic fertilizer
- Watering can
Note: These are just general kale growing guidelines. If your seed package has specific directions, follow them.
Step 1: Select a grow site and containers
Kale needs around 6-8 hours of sunlight a day, so be sure to choose a sunny windowsill, ideally, a south-facing one. If you don’t have a sunny window, you’ll need to get a grow light.
While you can select any type of container you like, make sure it’s at least 12 inches (30.5 centimeters) wide and deep to accommodate proper kale growth. If there aren’t already drainage holes at the bottom, remember to drill a few. If you plan to use terracotta pots, keep in mind that these tend to draw out moisture and you’ll need to monitor moisture levels more closely.
Step 2: Prepare soil and containers
Fill the pots with a mixture of potting soil and organic compost. Each pot should hold roughly 3 gallons (11 liters) of soil. The optimal soil temperature is between 50-85 degrees Fahrenheit (10-30 degrees Celsius).
Step 3: Sow seeds and thin seedlings
Sow around three or four seeds ¼ inches (5 millimeters) deep in each place you want a plant to sprout. Water until the soil is damp. Place a clear plastic bag over the seeds until seeds begin to sprout. Germination happens in 7-10 days. Make sure soil is kept moist.
Thin your kale seedlings by leaving the sturdiest ones until they are at least 6 inches (15.2 centimeters) apart. Depending on the size of your growing container, you may only have room for one plant per pot.
Step 4: Apply mulch
Once your kale plants are several inches tall, and properly spaced out, you’ll want to apply a layer of mulch around 1 inch thick (2.5 centimeters) to the soil. This helps retain moisture. Indoor containers are especially prone to drying out quickly.
You may need to water your kale plants daily to keep the soil moist.
Step 5: Apply fertilizer periodically
While not absolutely necessary, you may find that your kale plants benefit from a bit of nitrogen-rich fertilizer applied every two weeks or so.
How to harvest kale
When growing from seed, kale plants generally are ready to harvest in 55-75 days. The great thing about kale is you can harvest a few leaves as needed, and it’ll continue to grow.
To harvest kale, pick the larger outer leaves for use, and leave the smaller more tender leaves to continue to grow. With this method, you can pick more leaves again in about a week.
Or, some people prefer to harvest the entire kale plant. This is more suited to your outdoor garden however. With indoor gardens, you may like to have plants continually growing.
Depending on how much kale you eat, you might want to plant more seeds every several weeks to have a steady supply of fresh kale
Did you know that you can also grow kale microgreens? Microgreens are smaller plants harvested when only one to two inches tall.
How to use kale in the kitchen
Kale is a versatile plant with a variety of colors, textures, and flavors (depending on the variety). Here are just a few ways to use kale in the kitchen:
- Juice or blend: Blend the outer leaves for use in green juices and smoothies.
- Salads: The small, inner leaves are tender and perfect for eating raw in salads.
- Soups and stews: Tough, outer leaves, or leaves of more mature plants can be cooked until tender.
- Omelettes: Use kale like you would spinach and chop and add as part of a hearty breakfast.
- Baked: Use Dwarf Blue Curled (aka Scotch kale) for baked, crispy kale chips.
- Stir-fry: A splash of oil and garlic turns these greens into a tasty addition to stir-fry.