Contrary to popular belief, container gardening isn’t just for herbs. Many vegetables such as kale do well growing in pots as well.
You can grow kale in a pot that you place on the balcony, patio, or outdoors. You should use the right sized container and potting soil to grow kale. Grow them in the cool-season and provide 6-8 hours of direct sunlight. Ensure the soil gets sufficient moisture.
This cruciferous crop can thrive in the contained growing environment of a pot. I wanted to learn more about how to grow the vegetable successfully. Check out what I learned during my research below.
1. Pick the best time to grow kale
While they’re often available year-round at the grocery store, kale is a cool-weather crop. It does best when temperatures are relatively low. That means no summer growing.
You can grow kale in a wide range of hardiness zones. The plant does well from zones 2 to 10. But, you need to grow at the right times.
The goal is to start planting in the early spring. The latter half of the summer season works well, too.
Like all plants, kale takes time to develop. This is especially true in the early stages of the plant’s life cycle. Early starts give the crop some time to establish itself before producing those delicious florets.
The last half of the growing cycle is most important. During this stage, the temperature is going to have a greater impact on how the crop develops. Ideally, your plant should have exposure to temperatures no higher than 75 degrees Fahrenheit.
By planting in early spring or late summer, your plant will do much of its vegetable production in the cool fall temperatures.
The Effects of Heat on Kale
When grown in hot temperatures, kale will start to experience a litany of issues. The heat can stunt the growth of the plant, leaving you with no substantial harvest at the end of the growing season.
Not only that, but summer growing will increase the plant’s chances of bolting. This is when the plant focuses its energy on producing flowers rather than vegetables. The plant will grow flowers, rendering the tiny crop useless from a culinary standpoint as it turns bitter.
Interestingly enough, it’s the soil temperatures that are important here. Hot soil affects the roots more than hot air temperatures. There are ways to get around excessive heat by protecting the soil. But, it’s far easier to just grow the plant at the right times of the year.
2. Understand how long kale takes to grow
The growing time for kale depends on many factors. The most impactful is the variety you’re growing and how you start the plant.
When grown from transplants, you can expect to harvest your crop about 30 to 40 days after planting in the pot. But if you start from seeds, your wait time could be between 55 to 75 days.
There’s no right or wrong way to grow kale. Many gardeners choose to utilize seedlings because it shortens the growth time. Plus, it eliminates a lot of hard work. Sprouting seeds is not always easy, as the young plants are very delicate.
That said, growing from seeds does offer more control. You have a greater selection of varieties to choose from. Furthermore, gardeners can easily pick a cultivar that works for their particular region.
Overall, I would recommend planning for at least three months of growth.
3. Pick the right pot to grow kale
Choosing the right pot for your kale is paramount. Standard plants are capable of reaching heights of 24 inches. Meanwhile, they can have a diameter of about 12-18 inches.
Here are some tips on choosing the right pot.
The first thing to decide is the pot’s size. There are a couple of methods of growing kale in containers. You can either grow them singly or in a small group.
Growing singly is the preferred method. It reduces the chance of root competition and gives the plant plenty of space to spread. For a single kale plant, you will need a pot that can hold at least 5 gallons.
For two or three plants, you need something larger. You can keep a couple of plants in a large 15-gallon container. It should be at least 18 inches wide and 12 to 18 inches deep. Of course, bigger is always better when grouping plants together.
The color of your pot is about much more than style. Colors will absorb heat differently. Lighter colors tend to stay much cooler than darker ones.
It’s best to grow kale plants in light-colored pots. Remember: high soil temperatures can stunt growth and cause bolting. So, you want to do everything you can to keep that soil cool. The easiest way to do that is by choosing a light-colored pot.
Finally, there’s the material. Technically, you can grow kale plants in any container. They do just fine in plastic or stone pots.
That said, I would go with terracotta. It all comes down to keeping the soil cool. Terracotta is naturally porous. The material absorbs water. This keeps the soil cool and moist for much longer.
4. Prepare the pot to plant kale
Once you have found the perfect container, there’s still some work to do.
Kale can suffer from serious health problems if your pot is not well-suited to its growing preferences. These plants need ample drainage to flourish.
If the plant’s roots sit in water, they could experience root rot. Root rot will effectively stunt growth. In severe cases, it could even kill the plant completely.
To prepare your pot, take a look at its bottom. Are there drainage holes? If not, take a power drill to it and create some. You may even want to punch additional holes if your pot only has a couple.
Position the holes in the center and around the perimeter of the pot. Kale roots can penetrate up to a foot deep. Not only that, but they will spread wide. You need to give the soil plenty of opportunities to fully drain.
Some gardeners like to utilize drainage medium. Some examples of this include gravel, pebbles, or broken pieces of terracotta. This isn’t required. But, it doesn’t hurt to have that extra peace of mind. Some drainage medium allows the water to flow away from the roots and out of the pot.
Preparing the Soil
Next, it’s time to prepare your soil. Kale prefers well-draining soil with a pH of around 6.0. This plant likes some slight acidity. You also need to have a nutrient-rich soil to promote growth.
Amend some loam-based soil with rich compost. Then, add some sphagnum peat moss. The moss will lower the pH a bit. Once your soil is mixed, it’s ready for planting.
5. Plant the kale seeds in the pot
Starting from seeds gives you greater control over how your kale grows. It takes a bit more work and time. But, the results are well worth the payoff.
You have two different options here. You can start your seeds indoors or sow them directly in your pot.
Starting Seeds Indoors
If you choose to go this route, you’ll need to plan ahead. Timing is crucial here. It’s also dependent on the growing season you’re aiming for.
For spring growing, start the seeds 4 to 6 weeks before the last frost date. If you want to grow in the fall, start them 10 to 12 weeks before the first fall frost.
You can use a seed-starting tray. Those with individual pods are best. Place seeds about half an inch into the soil and cover them.
Keep the soil moist and place the seeds in a warm area. You can use a heat mat or place the tray on top of a warm appliance. Refrigerators work well.
Kale seeds are quite resilient. They can still sprout in temperatures as low as 45 degrees Fahrenheit. However, optimal temperatures for germination are between 65 and 85 degrees Fahrenheit.
Depending on the temperature, your seeds should germinate in four to seven days.
Sowing Seeds in Pots
Sowing the seeds in the pot is great if you live in a warm environment that doesn’t experience frost very often. You can plant the seed in a pot outside. This will eliminate the hardening-off process. Just make sure the seeds are protected from pests.
Simply bury the seeds half an inch below the soil. Bury a handful of seeds in the pot to get a good germination rate. You can always thin the seedlings later. Keep the pot in a warm space away from direct sunlight.
6. Plant kale seedlings in the pot
It doesn’t matter where you get your seedlings from. They could be store-bought store or seedlings you germinated yourself indoors. Getting the seedling to the pot is a crucial step in the process.
The seedlings are very delicate at this stage. It’s not difficult to damage the plant. So, you must use a careful and steady hand.
Seedlings are ready for planting when they have their first pair of true leaves. But before you do this, you must ensure that the seeds are hardened off.
The hardening off process only applies to seedlings that grow indoors. You have to get the delicate plant used to the outdoor environment. Otherwise, they can die from shock.
Start by placing the seedlings outside in a shady spot for a few hours. Then, bring them back in. With each passing day, expose the baby plants to more time outdoors. Increase sun exposure every day as well. Continue doing this until you can safely leave them out throughout the entire day.
When you get to this point, you’re ready to plant the seedlings in the pots.
Loosen up the soil in your pot. Create a small hole that’s an inch or two deep. The roots of the seedling are not very long. But, you don’t want to crowd them into a shallow hole.
Now, gently remove the seedling from its tray or growth cell. Gently shake off the soil. Be extra careful not to damage the roots. Place the seedling in the hole and fill it in will soil. If you’re planting multiple seedlings in a single pot, space them 12 to 18 inches apart.
Give your newly planted seedling a thorough watering. It’s important to keep an eye on your seedling for the first few days. Make sure that the pot stays moist and weed-free.
7. Choose the right location for the pot
Kale is a sun-loving plant. The crop does best when it has full sun exposure for at least six hours a day.
Place your pots in a sunny spot where they can bask all day long.
You must ensure that your plants are getting ample sunlight. If they don’t receive at least six hours, you will run into some problems.
During the growth process, a lack of sun will result in extended growth. The plant can become leggy. This means that the plant will use energy to produce longer stems and bigger leaves. It’s the plant’s attempt at reaching more sunlight. While it results in a bigger plant, your harvest will be small. The goal is to give your plants enough sun to use its energy for vegetable production.
Even if the crop does grow vegetables, quality could suffer without ample sun. Plants that receive less than six hours grow small vegetables with tight heads. The tight heads can easily crumble in your hands. Not exactly the most appetizing vegetable to eat.
8. Water the potting soil with the kale plant
Watering your kale plant can be a bit tricky. For many gardeners, the go-to is to saturate the soil. Some plants love this. Unfortunately, kale is not one of them.
These plants require even moisture. Pouring large volumes of water on the plant is only going to damage it. Even with well-draining soil, too much water can cause serious issues.
You run the risk of causing root rot. Plus, fungal issues can creep up around the base of the plant. To avoid health problems, you need to water the plant lightly.
Kale plants only need between 1 and 1.5 inches of water each week. That’s not a lot compared to other plants.
Limit watering to once or twice a week. Aim to keep the soil moist but not saturated.
The best time to water kale is in the early mornings. Focus the water on the base of the stem. Do not get water on the kale heads once they start developing. Doing so will only promote rot and fungus.
9. Thin the unwanted kale seedlings
Thinning is another crucial step you don’t want to ignore. Chances are, you started your seeds very close together. Mature kale plants need 12 to 18 inches of space to truly thrive. So, you’ll need to thin the herd a bit to avoid competition over water and nutrients.
The best time to thin kale seedlings is when they’re 1 to 2 inches tall.
Find the strongest seedling. That’s going to be the one that you want to develop further. Everything else that’s in the plant’s future growing space will have to go.
Use small gardening shears or pruners to snip each seedling at the base. Many like to simply pull the seedlings out. You can do this as well. But, there is a risk of damaging the root system of the seedling you want to keep. Make sure to cut those that are close to the primary seedling.
You can toss the discarded seedlings in your compost pile. Or, you can keep them. Kale seedlings and sprouts are very nutritious. They taste great in a salad, too.
10. Add fertilizer to the potting soil
Fertilization is a great way to give your plant a boost of extra nutrition. It can help your plant reach its full potential and develop larger heads. But, it’s not always necessary.
If you amended the soil well before planting, the kale should have all it needs to grow. You don’t have to worry too much about things like nutrient runoff. So, a well-prepared soil mix can support your plant throughout its life.
If you do choose to utilize fertilizer, you have a couple of options. You can use a slow-release product or a side-dress.
Slow-release fertilizers are best applied before you plant your kale. You can add the fertilizer during the preparation phase. This ensures that the nutrients supplement the plant during the growth cycle.
Standard 10-10-10 or 14-14-14 fertilizers work just fine. Mix the granules into the soil and treat it as you would traditional compost.
These products come in granular form that you must dilute in water. There are a couple of strengths available. For regular fertilization, you can use a low-strength formula. They work best if you want to fertilize every two weeks.
Generally, kale plants will only need one application of high-quality fertilizer. This application occurs when the plant starts heading. Dilute your mixture and apply it to the soil next to the plant. Avoid getting any on the stem, as this could cause burning.
11. Harvest kale from the pot
The best way to harvest kale is with the cut-and-come-again method where you keep pruning the leaves and it keeps growing more of them.
When the kale leaves are grown big enough, you can either pluck them or cut them off with a pair of gardening pruners. The stalk will still remain in the ground and keep growing new leaves.
You want to harvest the old leaves that have grown big. Avoid cutting the smaller leaves that are starting to grow from the center.
The best time to harvest kale is in the morning when the leaves will be fresh. They would taste even better if there is a light frost on them when they develop more sugar and become sweeter.
The growing season will end once the hot weather of summer or the freezing cold of winter arrives. You can harvest the entire plant before this happens by cutting it off at the base of the plant with the gardening pruners.
You can dispose of the oldest and lowest leaves of the kale plant because they will have the least flavor.