When Is Kale Ready To Harvest and How To Pick

Kale (Brassica oleracea) is much more than just a trendy leafy green. It’s a member of the brassica family — alongside popular veggies like cabbage, broccoli, Brussels sprouts, and cauliflower — that is incredibly easy to grow in the home garden.

Part of what makes kale so beginner-friendly is its impressive cold tolerance. While many vegetables grow best in warm climates, kale’s flavour is actually improved by frost. I highly recommend kale to any fellow cool-season gardeners.

Harvesting kale at the right time is crucial to getting the most from this nutritious crop. In this article, I explain how to tell when kale is ready to harvest and the best way to harvest leaves to ensure continued growth. 

when is kale ready to harvest
Kale plant ready for harvesting

When To Harvest Kale

It is possible to harvest kale in spring, early summer, and fall, with mid-summer often best avoided in warmer regions. As described by the University of Minnesota, heat and drought will turn kale very bitter, and yield a poor-tasting crop. To prevent this, you want to avoid growing and harvesting kale during the peak of summer or planting in an area with a location with partial shade away from the intense midday heat. 

Many gardeners plant two separate rounds of kale that are then harvested in the spring and fall, respectively, One of the wonderful things about this vegetable is the continued harvesting. By taking just a few outer leaves of several plants new leaves will continue to grow to extend the cropping duration.

Kale can even be grown and harvested throughout winter in particularly mild climates, as a hardy plant it will even cope with light snow and frosts.

When planning my harvesting period, I prefer to work backwards from my planned harvest date to determine the best time to plant kale in my garden. Keep in mind that each kale cultivar requires a certain number of days to mature. If your area’s final frost date is relatively late in the spring, I also recommend starting kale from seeds indoors to prevent frost damage and early bolting.

Kale Growth Cycle

Kale, like other brassicas, is a biennial plant. However, only the first year of growth has any value to us vegetable gardeners.

In its first year, kale produces large, edible leaves. These leaves allow the plant to store energy for winter and the following spring. They also make excellent salad greens.

The second year is when kale flowers and goes to seed. In some cases, a flower stalk will appear at the end of a kale plant’s first year of growth. This is known as bolting.

Bolting often occurs when kale is planted too early in the spring. The cool temperatures trick kale into thinking an entire winter season has passed and that it is time to flower.

Whether bolting occurs in the first or second year of growth doesn’t change the fact that flowering kale turns very bitter. Any plants that have bolted should be discarded instead of harvested.

How Long Does Kale Take To Grow

Most kale varieties are ready to harvest approximately 60 days after planting. However, this process can take up to 95 days in cases of slow-growing cultivars or poor growing conditions.

You can start to harvest baby kale in as little as 25 to 30 days after planting. Baby kale is another name for leaves that are harvested when they are young and tender.

How To Tell If Kale Is Ready To Pick

As a rule of thumb, kale is ready to harvest when the outer leaves are about the size of your hand. However, there is plenty of flexibility when it comes to harvesting kale from the home garden.

Baby kale, for example, is usually harvested when the leaves are 2 to 3 inches long. You want to wait until the plant has several sets of leaves this size to ensure a good harvest.

You can also harvest mature kale when it is a bit smaller if you want more tender greens. The only downside to harvesting kale early is that the total yield will be far less than if you waited just a few extra weeks.

While it’s nearly impossible to harvest kale too early, you can definitely wait too long. Old leaves may appear discoloured, get thick and tough, or they may even begin to rot. Simply remove these leaves from the plant and continue harvesting the newer growth towards the centre.

Picking a curly kale leaf
Pick curly kale before it gets tough

How To Harvest Kale

My go-to method for harvesting kale is to gently pull mature leaves away from the stem until they break off. Be careful not to damage the main stem itself as you do this. Alternatively, you can use a pair of clean garden shears or scissors to easily remove the desired leaves.

Only the largest, outermost leaves should be removed from a kale plant (unless, of course, you are harvesting baby kale). These leaves are the oldest and will quickly be replaced by newer growth.

Cutting Kale So It Keeps Growing

Kale will continue growing after harvest as long as the terminal bud remains intact. The terminal bud is located at the top of the centre stem and is where all new growth develops. Harvesting only the outermost leaves is the best way to prevent damaging the terminal bud.

To ensure good future harvests, I also recommend limiting the number of leaves cut from your kale plant. The usual advice is to harvest no more than one-third of a kale plant’s leaves at a time. The remaining foliage is necessary for the plant to continue photosynthesizing and growing.

How Many Times Can You Harvest Kale

Harvest outer leaves every 1 to 2 weeks during the peak growing season. As long as you follow the guidelines I described above, there is no set number of times you can harvest leaves from a kale plant before it stops producing. 

Kale will continue growing and producing until temperatures drop below 20°F. 

In areas where winter temperatures stay above this range, kale plants will produce throughout winter. Otherwise, you can extend your kale’s growing season by sheltering in-ground plants with fabric tarps or row covers in the fall. 

Varieties of Kale

As a plant species, kale is incredibly diverse. In addition to the many edible varieties worth growing, you’ll also come across some intended for ornamental use. 

Kale cultivars may differ in size, texture, colour, and leaf shape. However, deciding which kale varieties to plant in your garden largely comes down to how you intend to use the harvested leaves. Here are 3 types I recommend:

Cavelo Nero

This is my favourite kale, with its tall dark leaves making it a very handsome plant, offering a delicious flavour and tender leaves when picked at the right time. BBC Food describes the taste as “…pleasantly tangy, bitter flavour, with a sweet aftertaste”, which I is a nice description, it’s not too bitter so a great option for anyone looking for a milder flavour.

Curly Kale

Curly kale is the most classic form of this leafy green. It has curled or ruffled foliage and a distinctive peppery flavour. If you’re interested in growing “traditional” kale in your garden, a variety of curly kale is what you should plant.

Purple Kale

While several types of kale boast purple leaves, the most common variety is Redbor kale. Since the leaves are quite tough, Redbor kale is usually cooked rather than eaten raw. It’s also very popular in health food circles because it contains the antioxidant alpha-lipoic acid.

Redbor kale is grown as an edible vegetable as well as a cool-season ornamental. When choosing seeds for your kitchen garden, be sure to select those bred for culinary use. The texture and flavour of ornamental cultivars can be extremely unpredictable.

Red Kale

Red kale, or Russian Red kale, is often used in salads and other fresh dishes. This type of kale gets its name from its red stems. The actual leaves, however, are green. Red kale tends to be sweeter than other varieties but still has that distinctive kale pepperiness.

FAQ’s When Is Kale Ready To Harvest

Citation

BBC Food – Cavelo Nero

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Ben's horticultural interest grew when graduating from Hertfordshire University in 1997. Having contributed to numerous publications including Better Homes & Gardens, Garden Design Magazine, and The English Garden. He is also the author of Propagating Houseplants Made Easy.