Kale Square Foot Gardening And Companion Plants

Kale is one of the healthiest crops, and you can cultivate them via square foot gardening with companion plants and in the greenhouse. One kale plant only requires one square foot, and you can grow it with a lot of companion plants. Kale can be neighbors with buckwheat, sorghum, hairy vetch, herbs, legumes, onions, marigolds, nasturtium, and sweet alyssum.

What is square foot gardening?

Square foot gardening was a method developed by Mel Bartholomew in the late 1970s. In particular, it’s a gardening method that is best for raised beds in limited space. From the name itself, square foot gardening means you’re using blocks for planting compared to the traditional planting in rows. 

Ideal Humidity in a Greenhouse

You will divide a garden bed into a grid where you’ll plant a crop in each square foot block. This is a space-saving method because you’ll be planning the plants and their required space per square. Square foot gardening will only be effective and successful if you have planned and measured everything beforehand. 

Because of the small space required by square foot gardening, you can save time, effort, and money in raising crops. You can produce as much food as you would with planting in rows. It’s also an easy and straightforward gardening method that you can do yourself even as a beginner. 

You can create your own raised bed box, whether it’s 4×4, 2×4, or 4×12 feet, and fill it with fertilized soil. Afterward, lay a square foot grid on top of this box that will serve as your guide for plant spacing. However, you have to know the appropriate plant spacing per square foot.

What is the kale spacing per square foot? 

Kale is one of the best crops to grow with square foot gardening because it’s a medium-size plant where you can plant one per square foot. You also want a space of 12 by 12 inches for kale.  Following this recommended spacing for kale will prevent you from overcrowding the bed. 

You can sow seeds or transplant kale at the center of your square. And what’s great with kale is that you can grow it with companion plants for more efficient cultivation. So what plants can you grow alongside kale?

What are the companion plants for kale?

With kale, its companion plants are buckwheat, sorghum, hairy vetch, herbs, legumes, onions, marigolds, nasturtium, and sweet alyssum. It’s also friendly with other crops like artichokes, beets, celery, chard, cucumber, mint, potatoes, radishes, and spinach.

Companion planting is a great way to protect crops and nurture their growth because it can help attract beneficial insects and deter pests. It can also save space and make gardening more efficient. The importance of knowing the companion plants for kale is that planting just any crop can create competition for nutrients and even attract pests.

On the contrary, pairing kale with the plants we mentioned is like having the perfect neighbor. Let’s discuss why these plants and flowers are the best companions for kale. At the same time, which crops should you avoid planting with kale?


Buckwheat is a great companion plant for kale because it is a nitrogen fixer. Therefore, your kale can benefit from the additional nutrients in the garden. It also serves as ground cover to keep weeds at bay and seal moisture in the soil to prevent degradation. 


The size of the sorghum can act as a shade for your kale. This is advantageous if you want to minimize the harsh heat that your plant gets. Sorghum is best if you position it south of your kale. 

Hairy vetch

Similar to buckwheat, hairy vetch can add nutrients to the soil because it’s a nitrogen fixer. In fact, adding ground cover plants like these crops can increase the yield of the plot with them. And as a bonus, they attract beneficial insects too. 


Herbs like basil, chamomile, rosemary, sage, and thyme make great companion plants for kale. They keep pests away by attracting insects that will feed on them. They can also repel pests, and they don’t even compete for the nitrogen in the soil since they are light feeders. 

But besides the herbs we mentioned, cilantro, dill, and lemongrass are also wonderful plants to grow alongside the kale. These herbs attract beneficial insects like hoverflies and wasps. These insects can feed on aphids and other pests in the garden. 

Lemongrass itself also repels pests to make sure your kale grows healthily. 


Legumes make excellent companion plants for kale because they increase the nitrogen in the soil. This will help your kale to grow healthily without needing to compete for the nutrients in the soil. You can choose from bush beans or pole beans as companion legumes for kale. 


Onions and similar crops like shallots, chives, and leeks all grow wonderfully with kale. They can deter crop pests like aphids, moths, and mites to keep your kale healthy and pest-free. Cabbage loopers and flea beetles that commonly consume kale leaves are also driven away by these alliums. 


Besides these crops, flowers like marigolds, nasturtium, and sweet alyssum are also great additions to your kale garden. Not only do they look good and smell good, but they attract predatory insects as well. Hoverflies will feed on aphids, and nasturtium itself repels cabbage loopers.

These flowers aren’t even heavy feeders, so your kale has no competition for nutrients. Are there other companion plants that are great for kale? You can also consider planting artichokes, beets, celery, chard, cucumber, mint, potatoes, radishes, and spinach in your kale garden.

What plants should you not grow with kale?

While kale has a lot of friends, you shouldn’t grow it alongside sunflowers, tree of heaven, and black walnut. There are also some considerations if you want to plant kale alongside tomatoes and similar brassica plants like cabbage, broccoli, and cauliflower. 

Sunflowers, tree of heaven, and black walnut are allelopathic. Because of the biochemicals they produce, they don’t make good neighbors to kale as they can affect your crop. For example, the biochemicals from sunflower leaves can prevent the germination of the seeds that are close to it. 

On the other hand, the tree of heaven has chemicals in its roots and bark that can be detrimental to the growth of the neighboring plants. It can also attract pests like spotted lanternflies. And lastly, black walnut’s chemical can cause death to the plants that are close to its tree. 

Can you plant kale with tomatoes and other brassica species?

Tomatoes can reduce the population of pests called diamondback moths. If you think about it, this is beneficial for kale. However, you have to be mindful of feeding both plants because tomatoes are not light feeders like herbs. 

On the other hand, brassica relatives of kale like cabbage, broccoli, and cauliflower may not make good companions in some sense. Planting these crops together can mean that you’re attracting a large number of pests and diseases since they are close relatives. This can lead easily to an outbreak if you fail to address the issues immediately. 

Types Of Kale

The common types of kale are Curly, Ornamental, Chinese, Lacinato, Red Russian, Siberian, and Redbor. 

Curly kale

If you think of kale, chances are you imagine the curly variant. This is the most common type of kale, and it varies from pale to deep green color. It also has fibrous stalks and ruffled leaves, and its flavor is bitter and peppery that goes well in salads.  


Ornamental kale is a colorful variant that ranges from white, pink, and purple. It has coarse leaves and looks like a flower, so it’s commonly used as a garnish. However, ornamental kale is still edible and can add some texture to your dishes. 

Chinese kale 

Like the other varieties, Chinese kale is packed with vitamins and minerals, including vitamins A and C, calcium, and iron. You can eat it boiled or stir-fried, but it also tastes good steamed. If you lack broccoli for a recipe, you can use this variant as a substitute. 

Lacinato kale 

Unlike the previous kale types, Lacinato kale is not frilled and curly. Instead, lacinato kale is reminiscent of savoy cabbage with dark blue-green leaves and unique leaf texture. It tastes sweet and not as bitter as your common kale. 

Red Russian 

Red Russian kale looks like oak leaves or the outer leaves of a mature cabbage. It ranges from blue-green to purple-red, and it tastes a bit sweet. However, the stems are tough and fibrous, which can be hard to digest, so it’s important to remove them. 

Siberian kale

If you live in a cold region, you can grow Siberian kale instead. It is a variant that can withstand the cold, and its large leaves can handle a handful of pests. This gray-green kale tastes better cooked compared to other variants. 

Redbor kale

Similar to the Ornamental kale, the large Redbor kale is both stunning to look at and tasty to eat. Its dark red leaves with purple veins will look good on the plate and also for the garden. At the same time, it is still edible and healthy for consumption. 

How To Grow Kale

Growing kale via square foot gardening and in the greenhouse with companion plants will be successful if you educate yourself with various considerations. You must know the ideal temperature to grow kale, the best time to grow kale, how to take care of kale, and when you can harvest kale. At the same time, don’t forget the other requirements of the companion plants of kale. 

What’s the ideal temperature to grow kale

Unlike most crops, kale seeds are capable of germinating in cool soil. In particular, you want to plant them above 70°F. Exceeding this temperature can lead to tough kale. Afterward, you can keep the temperature above 45 degrees to ensure successful germination. 

When is the best time to grow kale

Depending on your region, you should consider when to plant. For example, if you’re planting during the warm season, plant your kale with some shade. On the contrary, plant kale in full sun if the climate is cool. 

Remember that it’s best to let kale mature at a cool temperature to prevent harvesting tough and bitter crops. You can sow seeds indoors as early as six weeks before the last frost to prepare them before the intense heat. For a continuous harvest, you can plant seeds or transplants every three weeks as well. 

If you sow seeds, kale will mature in 75 days. On the other hand, you can start harvesting at 40 days if you use transplants. 

How to take care of kale

You can give an inch of water every week, especially when you’re growing kale in the summer. Afterward, you can limit the amount once the cool weather starts. As for fertilization, make sure that your crops are well-fed throughout the growing season. 


When can you harvest kale?

A good indication that it’s time to harvest kale is when the leaves of the crops are the same size as a hand. Start harvesting with the outermost leaves and then work toward the center. Remember to leave some central leaves for continuous growth, and you can still harvest from it in 5 to 7 days. 

Growing Kale In The Greenhouse 

You can do square foot gardening with kale in the greenhouse along with other companion plants. It involves planting and germination, feeding and watering, and harvesting. What’s great with growing kale in the greenhouse is that it’s easy to meet these requirements, and you can refer to Krostrade.com for greenhouses for growing kale. 

Planting and germination

It’s best that you grow kale in the greenhouse six weeks before the last frost date. This way, you can have your crops ready before it gets too hot in the summer. Kale will still grow in warm weather, but the plants end up bitter, so it’s best to avoid that. 

Depending on the kale variety, you can even harvest crops after a snowfall or have a winter crop. Now, in the greenhouse, remember to plant the seeds about half an inch under fertile soil. The soil should be rich in nitrogen and slightly acidic, and you can keep the soil moist with mulch. 

Kale can take ten days to develop, and you can transplant them when the seedlings are about 9 inches tall. 

Feeding and watering

Once your kale seedlings emerge, you can start fertilizing at a rate of 50 to 100 pm N and K. Then, you can increase the rate at 150 to 250 ppm N and K when you transplanted the crops. Once the temperatures drop, you can reduce fertilization to 50 ppm N and K to ensure good coloration on plants. 

As for the watering requirements, you can use an automated watering system or drip irrigation in the greenhouse. It’s important to keep the soil moist but never overwater the crops. 


You can harvest kale from the base up to get mature single leaves. However, you can also harvest full heads of kale. Just remember that after the first frost, the leaves will no longer grow, and those that are touching the ground will rot. 


Benefits Of Growing Kale

Growing kale via square foot gardening with companion plants outside or inside a greenhouse offers a lot of benefits. With kale, you can have your own source of nutrient-rich crops, improve the look of your garden, and get continuous production.

Have your own source of nutrient-rich crops

Growing kale means that you will always have access to freshly-harvested nutrient-rich crops. You can get your own kale in your garden or greenhouse for a quick salad or vegetable stir-fry. Kale is easy to grow and eat, but it’s also a good source of vitamins and minerals.

Kale is rich in vitamins A and C, as well as folate and minerals like calcium, potassium, magnesium, iron, manganese, and copper. These are all important nutrients to sustain the body and keep all the processes working efficiently. 

Improve the look of your garden

The different varieties of kale offer various colors and textures. They are not only aesthetically edible pieces on the plate. But kale also improves the look of your garden because of the varieties’ unique colors and looks. 

Continuous production

Another advantage of growing kale among other crops is that it’s resistant to cold temperatures. Some variants like the Siberian kale are even hardier. And since you can start harvesting single leaves, the plant will continue producing throughout the growing season. 


One plant of kale requires one square foot, and you can grow it alongside buckwheat, sorghum, hairy vetch, herbs, legumes, onions, marigolds, nasturtium, and sweet alyssum. Square foot gardening is an excellent way to reap the benefits of kale, even with limited space and time. Cultivating this healthy and delicious crop in the greenhouse will also ensure that it will always get the requirements for a successful harvest. 

You can choose a kale variant that matches your region and preference. And as long as you are knowledgeable of the ideal temperature to grow kale, the best time to grow kale, how to take care of kale, and when you can harvest kale, you shouldn’t have any problem with this hardy plant. Educating yourself with square foot gardening and kale farming in the greenhouse is also a must for a positive outcome. 

Leave a Comment