The 5 Kale Growing Stages & Development (Guide)

Regarded as a highly nutritious superfood, kale is a favorite amongst gardeners for the winter veggie garden.

With its effortless growing requirements and tolerance to cold temperatures, you can expect to have a good supply of fresh kale to harvest for at least six months of the year in temperate climates.

Kale goes through 5 stages of its growth cycle, starting from the seeds being planted and germination, followed by the seedlings being developed.

After the seedlings have formed, the vegetative growth stage will commence, and the kale lifecycle ends when you harvest it.

Whether it’s your first-time growing kale, or you are an avid veggie gardener, this article will shed light on the different stages of growth that kale goes through and the techniques you can use to help it along the way.

How Long Does Kale Take To Grow?

Kale is part of the Brassica family, which includes a range of widely known vegetables such as broccoli, cabbage, cauliflower, turnips, and many more.

As kale is a biennial plant, it takes two years to go through its full cycle, but most varieties are grown by gardeners as perennial which means it is fully harvested in the first year.

By allowing the plant to go through the flowering stage, you will stop leaf production, and the plant will concentrate on reproduction.

As kale is grown for its nutritious leaves, once the weather warms up and the plant begins to bolt, it is a sign that the kale growing season has ended. Kale reaches a matured size of 1-2 feet tall to 1-2 feet wide.

The root system of kale is medium depth and can extend 18- 24 inches long in the soil. This makes it ideal for growing in containers or garden beds.

Common nameKale, Ornamental Kale
Scientific NameBrassica oleracea
Family NameBrassicaceae
TypeHardy Biennial Vegetable
OriginEastern Mediterranean and Asian Minor
Maturity Size1-2 feet wide 1-2 feet tall
USDA Hardiness zone7-9
Light RequirementsFull Sun to light shade
SoilWell drained, Ph 6.0-7.5

Check out this time-lapse video of the kale growing stages:

5 Kale Growing Stages To Follow

Kale can be grown outdoors in full sun or part shade during the winter or indoors in window boxes or a conservatory.

As with other plants, kale seeds can be started indoors until they reach a good size to be planted out.

Kale takes 3 months to reach full maturity when in suitable conditions. If you want to speed up the process you can transplant seedlings that have been started in a local nursery.

Transplanting seedlings from a nursery will save you two months of care and you can start harvesting kale roughly one month after planting.

Follow the kale grow stages below to ensure you reap the rewards of a bumper crop this season.

1. Planting Seeds

Begin by planting the kale seeds in early spring or early fall.

To sow seeds in early spring, ensure you are planting a couple of weeks before the final frost date. You can start the seeds off by using a seedling tray or egg carton.

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Fill each cell of the seedling tray with an all-purpose well-draining potting soil. Kale thrives in high-nitrogen soil that is rich in nutrients.

Try adding a few scoops of organic matter or compost to the potting soil. You can purchase all-purpose potting soil from a local gardening store or the gardening section of a department store.

After each cell of the seeding tray is full, use a spray watering can to water the soil. Plant the seeds ½ inch deep into the soil and cover the seeds with a light layer of the potting mix.

If you are sowing the seeds directly outdoors, be sure to give them adequate spacing. One to two feet apart is a good distance to ensure they have plenty of space to fully mature.

If plants are grown too close together, you can run the risk of poor air circulation which will cause fungal infections and pests.

Try to avoid planting seeds in clay or sandy soil. These soil types compact over time and can cause root rot and stunt the growth of the plant.

Keep the seeds moist after planting and don’t let the soil dry out too much.

2. Seed Germination

Seed germination is the second stage of the kale’s growth cycle. Luckily, kale seeds don’t need high temperatures to germinate, and you can expect germination to happen around 8 days after planting.

To speed up the germination process, you can soak the seeds in lukewarm water for 24 hours before planting. Germination happens when the tiny seed case starts to crack and a small shoot forms.

During this time, it’s best not to move the seedling tray and keep them in the same spot to let them continue to the next stage of their lifecycle. As the kale seeds continue to germinate, keep the soil moist by using a light spray bottle.

Avoid using any water application at this stage. The seed hasn’t produced any root structure so it’s still very lightweight and can be blasted out of the soil.

3. Kale Seedling Stage

As the small kale sprouts grow into seedlings, they will start to form their first true set of leaves. These leaves are called cotyledons.

Cotyledons are used to provide light from the sun and help the kale plant photosynthesize in its early stages.

After 2 weeks, as the plant begins to mature, it will likely discard this set of leaves and continue to grow new leaves from its center.

During the kale growth cycle’s seedling stage, seedlings must receive 6-8 hours of direct sunlight to enhance their growth.

Continue with a watering regime where the soil is kept moist and when the seedling has produced around 5 leaves and is about 3 inches tall you can start considering where to plant them.

If you have already directly sown, the seeds in the beds outside, you can use a plastic bottle of clear plastic cover to protect the seedlings from any harsh weather changes or birds.

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4. Vegetative Growth

After potting or transplanting into the garden, the vegetative growth stage occurs. The seedlings have become over 3 inches tall and have produced four or more sets of leaves.

Many gardeners refer to this stage as ‘coming into full leaf’.

During this time, it is important to ensure the plants do not experience any stress as it can cause them to bolt, which means they will prematurely produce seeds, and the leaves will no longer be edible.

As the leaves have started to mature, the plant is also working below the soil surface too. The kale plant will be producing a healthy root system during this stage which makes it prime time to give it a boost of nutrients.

Use a balanced fertilizer of 10-10-10 (10% Nitrogen, 10% Phosphate, and 10% Potassium). You can use a granulated slow-release fertilizer or a liquid fertilizer.

Either way, follow the instructions on the back of the pack before application.

Continue with your normal watering routine at this point of the kale’s growth cycle, and you will prevent the plant from dying out and growing tough leaves.

5. Harvest

This is the time you have been waiting for! The harvest stage of the kale plant will happen when the plant has reached 6-8 inches tall.

If you start harvesting during the peak growing season, you can expect to continue to harvest new leaves every two weeks. When harvesting kale leaves, you can either use a clean, sharp pair of scissors or secateurs.

Some gardeners are happy to gently pluck the outer leaves off the plant. This can potentially wound the stem and slow down vegetation. Use a clean cut to ensure you don’t cause your new kale plants any harm.

As mentioned, snip away at the outer leaves of the kale plant when they are 6- 8 inches (15-20 cm) tall. The kale will continue to produce new growth in the center of the plant and will bush out.

Does Kale Regrow After Cutting?

Kale regrows after cutting, providing that it still receives the suitable light (6-8 hours) and correct temperature (65-75°F) requirements. Some reasons your kale may stop growing are due to root rot, disease, or pest infestation.

Root rot is common when the kale plant is not planted into well-draining soil, or there is an excess of salt buildup from over-fertilizing.

Make sure you plant the kale seedlings in well-draining soil that is rich in organic matter. Regularly check your kale plant for any pests or diseases and use an organic pesticide or fungicide to combat these problems.

How Tall Does Kale Grow?

Kale grows 1-2 feet tall and 1-2 feet wide when grown outside. The leaves will grow to 8 inches (15-20 cm) in length and 6 inches (10-13cm) in width.

A good rule of thumb is to allow the kale leaves to get to the size of your hand when harvesting. Allowing the leaves to grow beyond this size will cause a bitter taste and a rough texture.

Which Type Of Fertilizer Is Best for Kale?

The best fertilizer to use on kale is a well-balanced all-purpose fertilizer. You can purchase these online or in your local gardening stores.

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Look out for a 10-10-10 ratio on the label. This means 10% Nitrogen, 10% Phosphate, and 10% Potassium.

Slow-release granulated fertilizers are great if you don’t have access to organic fertilizers, such as rotted chicken manure, fish manure, or worm castings. When fertilizing, follow the instructions on the packet.

Less is more with fertilizer, as the damage to the plant from over-fertilizing can be irreversible or a challenge to correct later on. Apply fertilizer once a month and mulch the top of your plants to prevent weeds.

FAQ About The Kale Growing Stages

What are signs that kale is done growing?

Kale stops growing when the plant overwintered and started to produce flower stalks.

Remove the plants from the ground or pot and remove the leaves. You can store the clean leaves in a plastic container or bag in the fridge for up to 6 days.

Can you over water kale?

Yes, but overwatering kale will cause the roots to rot and stunt growth.

Water when the first 2 inches (5cm) of the soil is dry. You can check by pushing your finger in the soil. If your finger comes out clean, then it is dry and you can give it a drink.

Should you let kale flower?

Letting kale start its flowering stage is only beneficial if you want to attract bees to your garden or collect seeds for the following season.

After the kale has started producing flowers, it will cause the leaves to have a bitter taste and rough texture.

How often should you water kale?

Water kale when the first top 2 inches (5 cm) of the soil is dry. You can check the soil’s moisture levels by inserting your finger to feel moisture or by using a moisture meter available from garden stores.

Give the kale plants 1-2 inches of water each week or when the soil surface has dried out.

Finishing Up

Kale is a great winter crop to grow and has many uses in the kitchen. With a little bit of care, you can ensure that you have an abundant supply of nutritious leafy greens throughout the winter and fall. The most important factor when planting kale is the time of year; any hot temperatures will cause the plant to bolt and start flowering. Once this has happened, the leaves will no longer be edible. Plant seeds in early fall or early spring to avoid the summer’s peak temperatures.

Lucy Young

Meet Lucy, a seasoned gardener with a green thumb and a wealth of experience cultivated over 10 years in her own backyard oasis. Now, she channels her passion into writing, sharing invaluable gardening knowledge on her website. From nurturing plants to expert pruning techniques, Lucy's articles are a treasure trove for both seasoned enthusiasts and budding gardeners. Join her on this leafy journey as she sprinkles insights, tips, and tricks to help you create your own flourishing paradise. Get ready to dig into her gardening wisdom and unlock the secrets of a thriving garden!

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