Master Kale Growing Stages: Tips for Thriving Plants

Published on:

Kale, a nutritious superfood and a favorite among garden enthusiasts, is a must-have addition to your winter veggie garden.

Its simple cultivation requirements, coupled with its ability to withstand cold temperatures, make it an ideal crop for at least six frosty months of the year in temperate climates.

From planting the seeds and germination to developing seedlings, through vegetative kale growth stages, and finally, harvest—kale goes through a fascinating journey. Whether you’re a first-time kale grower or a seasoned veggie gardener, this comprehensive guide on kale’s growth stages and care techniques is sure to enlighten you.

Mastering the Growth Stages of Kale

For most of us, kale is synonymous with those vibrant, blue-green leaves we spot at farmer’s markets and grocery stores. But what we often overlook is the 2-3 months of meticulous care and nurturing that went into producing those stunning leafy bundles.

Like several garden crops, kale undergoes a series of swift transformations within a short span. It’s most vulnerable as a seedling, but as it progresses through its growth stages, it becomes increasingly resilient and self-reliant. This guide aims to familiarize you with the 7 stages of kale growth and equip you with the knowledge to nurture your kale crop effectively throughout its lifecycle.

1. Starting with Seeds: Your Guide to Successful Kale Planting

Kick off your kale journey in early spring or early fall. Timing is everything when it comes to planting kale seeds.

If you’re choosing to sow in early spring, make sure to do this a couple of weeks before the final frost date. You can kick off the growing process by using a seedling tray or even an egg carton – a great way to recycle and garden at the same time!

When sowing kale, opt for an all-purpose well-draining potting soil which you can easily find at your local gardening store or the gardening section of a department store. Kale loves to grow in high-nitrogen soil that’s packed with nutrients.

To boost your soil further, consider adding a few scoops of organic matter or compost to the potting soil.

Once your seedling tray is full, use a spray watering can to dampen the soil. Plant the seeds ½ inch deep into the moist soil, then cover them with a light layer of the potting mix.

If you’re sowing the seeds directly outdoors, remember to give them enough space to grow. A distance of one to two feet apart will ensure they have plenty of room to reach their full potential.

Avoid planting seeds in clay or sandy soil as these types can compact over time, leading to root rot and stunted growth.

After planting, keep the seeds moist and don’t let the soil dry out too much.

2. Germination: What to Expect

The second stage of the kale’s growth cycle is germination. Good news – kale seeds don’t require high temperatures to germinate, and you can expect this process to start around 8 days after planting.

To speed things up, you could 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 to leave your seedling tray in one spot to let the seeds continue to the next stage of their lifecycle. Keep the soil moist with a light spray bottle – avoid using a heavy water application at this point. The young seedlings hasn’t developed any root structure yet, so it’s still very lightweight and can be easily blasted out of the soil.

3. Navigating the Kale Seedling Stage

Early microgreen of a kale seedling, emerging from compost soil, in a vegetable garden. Growing the leafy vegetable from seed, which has just germinated.

The seedling stage, extending from germination to the time of transplanting, is crucial in the life of your kale plant. This phase is delicate and demands careful monitoring and regular watering. At this stage, your baby plant is most vulnerable, and providing the right conditions can make a significant difference in its growth.

Kale plants start their life cycle as tiny black seeds – strikingly similar to their brassica cousins (broccoli, cauliflower, brussels sprouts). The seeds should be planted half an inch deep in well-drained, loamy soil rich in organic matter. An ideal soil pH level for kale ranges from slightly alkaline 6.0 to 7.5. If your soil is acidic, consider enriching it with compost, wood ash, or dolomite lime.

Typically, kale seeds are sown during two main periods:

Despite kale’s reputation for cold hardiness, its seeds need warmth for even germination. A soil temperature between 70 and 90°F is ideal. To ensure the seed starter mix maintains a temperature above 75°F until germination, use a soil probe thermometer. After germination, the plant can tolerate cooler soil temperatures.

Seedling Stage Pro Tip: At this stage, kale plants are extra vulnerable to cold weather, dry soil, and pest pressure. Using a row cover can solve these issues. As a seasoned vegetable farmer, I always protect my kale seedlings with a layer of row fabric. This creates a cozy microclimate, retains moisture, and keeps pests like flea beetles at bay.

The row cover also protects kale from the cabbage butterfly, which lays eggs that hatch into destructive cabbage looper caterpillars. I’ve seen farmers lose entire kale crops to these pests emerging from hibernation, so don’t skip this protective step!

You can drape the row cover directly over your kale seedlings or create hoop supports using bent wire or arched PVC. Secure the cover with sandbags, rocks, or landscape staples. A raised bed makes securing everything easier. You can keep the kale under the row cover throughout spring until the temperature under the fabric gets too high.

4. Growing Kale in its Teenage Phase

Often, we find the perfect term to describe a situation in the least expected places. The term “teenager” isn’t a scientific term, but it aptly characterizes the transition phase of kale from being a seedling to becoming a mature plant. Kale plants in this stage are usually found in cell trays or have just been transplanted into the garden.

When you buy kale starts from a store, they are typically at the cusp of this teenage phase. These plants are around 4-8 inches tall, boasting several sets of medium-sized true leaves. However, the leaves might not be large enough for harvest, unless you have a preference for baby greens.

Here’s what you need to know about this phase:

One crucial factor to remember during this phase is soil drainage. The plants work tirelessly to expand their roots and anchor into the soil in preparation for a lengthy growth season. If your soil is heavily compacted or high in clay content, it complicates the establishment of kale plants.

Pro Tip for the Teenage Stage: Before transplanting your kale, consider broad forking. Broadfork is a substantial garden tool that aerates the soil without tilling it, and it can be used to mix in compost without disrupting the below-ground ecosystem. You can also use a pitchfork to loosen the lower soil. Avoid tossing and flipping the soil layers.

Broadforking creates ample pore spaces and air holes, facilitating the breathing and expansion of kale’s roots. If you’re using a well-prepared raised bed, broad forking may not be necessary as your soil layers already offer plenty of texture and aeration.

Inadequate drainage makes the kale plant susceptible to root rot or the dreaded (and incurable) Black Leg disease. Remember, like all brassicas, kale dislikes “wet feet.” If these plants are sitting in water or soggy soil, they will grow very slowly or may die before they reach the maturity phase.

If you’re unsure about your soil drainage, add more aerating materials (compost, vermiculite, perlite, peat moss, or coco coir) and cut back on watering.

During this stage, it’s crucial to ensure that the plants don’t experience any stress as it might cause them to bolt, which means they will prematurely produce seeds and the leaves will no longer be edible.

As the leaves mature, the plant also works below the soil surface, producing a robust root system. It’s prime time to feed it 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. Follow the instructions on the back of the pack before application.

Continue your regular watering routine at this point in the kale’s growth cycle, and you will prevent the plant from drying out and growing tough leaves.

5. Harvest

Harvesting kale is a rewarding task, and technically, you can pick the leaves at any point. However, for optimal growth, it’s best to start harvesting the outer leaves when they are at least the size of your hand. Leave at least two robust clusters of leaves in the center to fuel further growth.

Microgreens and baby kale salads are harvested while the plant is still in the seedling stage. Though bear in mind, harvesting at this stage can slow down the plant’s growth. So, if you’re looking to enjoy fresh kale throughout the season, wait until the leaves have grown to palm size.

The most succulent, salad-ready kale comes from young leaves that are about 6-8” long. You may need to utilize scissors or a knife to cut the leaves at this stage, as snapping them off could potentially harm the developing stem.

For steamed kale or larger bundles of greens, you’ll want to wait until the leaves are about 12” long. These can be easily snapped from the robust central stalk. Start by harvesting the largest bottom leaves first, leaving the upper core to continue growing.

When the kale plant reaches 6-8 inches tall, it’s time for the harvest you’ve been waiting for! If you start harvesting during peak growing season, you can expect to gather fresh leaves every two weeks. When gathering kale leaves, use a clean, sharp pair of scissors or secateurs.

Avoid plucking the outer leaves off the plant directly, as this could potentially wound the stem and slow down growth. Instead, make a clean cut to ensure your kale plant remains unharmed.

As a rule of thumb, snip away the outer leaves when they are 6-8 inches (15-20 cm) tall. The kale plant will continue to produce new growth in the center, resulting in a bushier appearance.

6. Maturity Stage

Once kale has matured, it becomes incredibly hardy and requires minimal care, save for regular harvests. Most kale varieties typically take 50-70 days to mature from the time of seeding. You can find the estimated Days to Maturity noted on your seed packet or in a seed catalog.

During the maturity stage, the central stem of the kale plant begins to resemble a tough stalk. By the end of its lifespan, a kale stem can become a rugged 3” thick woody wand. This makes harvesting a cinch, as you can easily snap off the outer leaves without worrying about damaging the stalk.

As long as fall kale reaches maturity before the first hard frost, it can last throughout the winter in zones 5 and warmer. There are even reports of the ‘White Russian’ kale variety surviving in negative temperatures!

Understanding the Bolting Stage for Kale

Seeing kale in its reproductive stage is uncommon for most gardeners, as kale is usually considered an annual plant and harvested before it starts flowering. However, factors like extreme heat or certain stressors can cause kale to bolt in its first year.

The bolting phase of kale marks the end of the plant’s life. This article will guide you on how to prevent bolting or how to enjoy the unique beauty and benefits of kale’s raab flowers.

Key Points in the Bolting Stage

Understanding the Life Cycle of Kale

Kale is technically a biennial plant, meaning it takes two full growing seasons to complete its life cycle:

However, kale can bolt in its first year if exposed to significant temperature fluctuations or water stress.

Preventing Kale from Bolting

To prevent kale from bolting, consider the following tips:

If your kale has begun to bolt, the leaves may start to taste bitter. This is a signal that the plant is shifting into the reproductive stage, where it will go to seed and eventually die.

Extending Your Kale Harvest

You can extend your leaf harvest and delay bolting with these strategies:

When your kale eventually blossoms, there is no turning back. But don’t worry – kale flowers are edible and delicious! These eye-catching yellow blooms are similar to mustard flowers and make a beautiful summer garnish.

Enjoying Kale Flowers

Here’s how to enjoy kale flowers:

Understanding When Your Kale is Ready to Harvest

Kale, a nutrient-rich leafy green, is ready to be plucked from your garden when its leaves have grown to about the size of your hand. A good rule of thumb is to harvest around a fistful of outer leaves each time, taking care not to pluck more than one-third of the plant at a single go.

It’s crucial to avoid picking the terminal bud positioned at the top center of the plant. This bud plays a vital role in maintaining the plant’s productivity.

Interestingly, kale continues to grow until temperatures plummet to 20°F/-7°C. Don’t halt your harvesting activities; in fact, a touch of light frost, can actually enhance the sweetness of kale. To prolong your harvest period, consider protecting your kale plants with row covers, tarps, or even old blankets propped up by hay bales.

The Art of Overwintering Kale

Overwintering kale isn’t a common practice among growers. This is because the leaves produced in the subsequent season tend to be somewhat bitter, compromising their taste. In colder regions, the oldest leaves will typically perish.

Once kale plants have completed their leaf production phase, they enter the reproductive stage. During this time, the plant concentrates on producing flowers and seeds. Come spring, your kale plant will exhibit tall stalks topped with yellow flowers, designed to attract pollinators. This makes kale an excellent companion plant.

While these flowers add a touch of beauty to your vegetable garden, they can cause the kale leaves to become tougher and more bitter. However, they remain edible and can be included in various dishes. Some kale cultivars, such as Siberian and Russian kale, even produce edible flower buds.

Eventually, you’ll notice the emergence of long, thin, green seed pods as the plant continues to grow. These pods signal the end of each kale plant’s life cycle, containing seeds that can be used to grow more kale. If you’re interested in collecting these seeds, wait until the seed pods dry before removing them. This will reveal the small seeds nestled within.

Cultivating Kale: A Comprehensive Guide

Kale, a member of the Brassica family, is a nutritional powerhouse that shares its lineage with well-known veggies such as broccoli, cabbage, cauliflower, and turnips.

While it biologically completes its life cycle in two years, many gardeners grow kale as an annual crop, yielding a harvest in the first year itself.

The key to successful kale cultivation lies in understanding its growth stages. Once the plant enters the flowering phase, the leaf production ceases, and the plant focuses on reproduction. Therefore, when the weather warms up, and the kale starts bolting (flowering), it’s a signal that the growing season for kale has concluded.

With a mature size of 1-2 feet in both height and width, kale plants are ideal for container or raised bed gardening due to their medium-depth root system that extends 18-24 inches into the soil.

Here’s a handy table summarizing the kale growing stages:

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

For a more dynamic perspective, check out this time-lapse video of the kale growing process:

Does Kale Regrow After Cutting?

You’ll be pleased to know that kale does regrow after cutting, provided it receives the necessary light (6-8 hours daily) and temperature (65-75°F) conditions.

However, there are a few obstacles that might halt your kale’s growth, including root rot, disease, or pest infestation. Root rot is a common issue when the kale plant is placed in poorly-draining soil or over-fertilized, leading to excess salt buildup.

To ensure healthy growth, plant your kale seedlings in well-draining soil rich in organic matter. Regularly inspect your kale plant for any signs of pests or diseases. If you spot any, don’t panic. Simply use an organic pesticide or fungicide to tackle these issues.

How Tall Does Kale Grow?

When grown outdoors, kale typically reaches a height and width of 1-2 feet. The leaves can grow up to 8 inches (15-20 cm) in length and 6 inches (10-13cm) in width.

A useful harvest tip: wait until the kale leaves are about the size of your hand before harvesting. If the leaves grow larger than this, they tend to develop a bitter taste and a tough texture.

Top-Notch Fertilizers for Kale: Make Your Greens Thrive

When it comes to kale, the best fertilizer is a well-balanced all-purpose variant. You can readily find these in online stores or local gardening shops near you.

Keep an eye out for a label that reads ’10-10-10 ratio’. This magic combination of 10% Nitrogen, 10% Phosphate, and 10% Potassium is the secret sauce your kale needs to flourish.

If organic fertilizers like rotted chicken manure, fish manure, or worm castings are out of reach, don’t fret. Slow-release granulated fertilizers are a great alternative. Always remember to follow the instructions on the packet when fertilizing.

Remember, less is more when it comes to fertilizing. Overdoing it can damage your plant irreparably or create issues that are tough to correct down the line. A monthly dose of fertilizer and a good mulch on top of your plants to deter weeds should do the trick.

Kale Maintenance and Care: Watering Practices and Overwatering

Did you know that you can actually overwater kale? Overwatering can cause the roots to rot and stunt the growth of your plant.

Water your kale only when the top 2 inches (5 cm) of the soil has turned dry. You can check this by inserting your finger into the soil to feel for moisture or, for a more precise measure, use a moisture meter, easily available at garden stores.

Aim to give your kale plants 1-2 inches of water each week, or whenever the soil surface has dried out.

To Flower or Not: The Kale Conundrum

The decision to let your kale bloom is a matter of preference. If you’re aiming to attract pollinators to your garden or collect seeds for the next growing season, then let those kale flowers burst forth! However, if your goal is a tasty and tender harvest, you might want to halt the blooming process in its tracks.

Once the kale begins to flower, the leaves can take on a bitter flavor and a rough texture, making them less than ideal for your next stir-fry or salad.

Frequently Asked Questions about Kale’s Growing Stages

We’ve compiled a list of common queries related to the growth and maintenance of kale. Let’s dive in!

How Can You Tell When Kale is Done Growing?

Kale wraps up its growth when the plant has overwintered and starts to sprout flower stalks. At this stage, it’s time to bid adieu to your kale plant.

You can gently uproot the plant and remove the leaves. Make sure to give the leaves a good rinse before storing them in a plastic container or bag. Stored properly in the fridge, your kale leaves can stay fresh for up to six days.

Is Overwatering Kale a Thing?

Absolutely. Overwatering is a common gardening misstep that can lead to root rot, stunting your kale’s growth.

To avoid overwatering, wait until the top 2 inches (5cm) of the soil is dry. You can check this by simply pushing your finger into the soil. If it comes out clean, your soil is dry and ready for a watering session.

Should You Let Kale Flower?

We’ve brushed upon this earlier, but it bears repeating. Allowing kale to flower can be beneficial if your aim is to draw bees to your garden or harvest seeds for future planting.

However, flowering kale can lead to bitter-tasting, rough-textured leaves. So, if it’s a delicious harvest you’re after, you might want to intervene before the blooming stage.

How Often Should You Water Kale?

Watering frequency for kale is tied to the moisture levels in your soil. As a rule of thumb, water your kale when the top 2 inches (5 cm) of the soil feel dry to the touch.

You can also use a moisture meter, available at most garden stores, for a more precise measurement.

Typically, kale plants need around 1-2 inches of water each week, or whenever the surface of the soil has dried out.

How to Properly Store Your Kale

Keep your kale fresh and ready for use by storing it in a loose plastic bag tucked away in your refrigerator. If stored correctly, it should remain fresh for approximately one week.

Wrapping Things Up: Growing and Utilizing Your Winter Kale Crop

Kale is an excellent winter crop that is not only easy to grow but is also versatile when it comes to kitchen use. A little dedication and care can ensure a continuous supply of this nutritious leafy green throughout the chilly winter and fall months.

However, the most critical factor to consider when planting kale is the timing. Any exposure to high temperatures will cause the plant to bolt and start flowering. Sadly, once this occurs, the leaves lose their edibility. To avoid this, it’s best to plant your kale seeds during the early fall or early spring to dodge the peak summer temperatures.

Photo of author


Adam White is the founder and chief editor at He has years of experience from years of Gardening, Garden Design, Home Improvement, DIY, carpentry, and car detailing. His aim? Well that’s simple. To cut through the jargon and help you succeed.