Kale is a versatile, leafy green vegetable that is packed with antioxidants and nutrients. The ultimate cut-and-come-again vegetable it is also easy to grow and, as this guide explains, harvest.
As well as explaining how to harvest kale we will share lots of useful care and growing tips, enabling you to get the best from your crop.
What is Kale?
Sometimes known as the curly leafed cabbage, there are a range of different Brassica Oleracea varieties available. As well as the common green leafed varieties there are also red, purple, yellow and ornamental types. In addition to color, you can identify the different Brassica Oleracea varieties by their stem length and leaf shape.
The plants come in a range of shapes, sizes and colors
This is a cold hardy plant that survives well into winter in many USDA growing zones. You can even overwinter the plants for an early spring harvest.
When to Harvest Kale
When you harvest kale depends on both the variety you are growing and why you are growing the plant. If you are growing the plants for baby leaves you can start to harvest kale sooner than if you want larger, mature leaves.
Starting the seeds undercover and transplanting once the last frost date has passed can also speed up the growing process, reducing how long you need to wait before you can start to harvest kale.
Plants directly sown into the ground require 55 to 75 days of growth before they are ready for cutting and eating. Seedlings started undercover in a MIXC Seed Starter Tray and transplanted into their growing position are ready in around 35 to 40 days.
Starting the seeds undercover enables you to cut fresh leaves sooner.
You can harvest kale’s baby leaves around 25 to 30 days after sowing. Red Russian is one of the best varieties to select if you want baby leaves.
If you are growing the plants for microgreens, you can pick the leaves even sooner.
In favorable conditions, you can start to harvest kale around 60 days after transplanting the seeds to their final growing position. At this point each plant should have at least 10 leaves. The leaves in the center of the plant are smaller than those on the outside.
The kale harvest period usually begins in late spring. If treating the plants as a cut-and-come-again crop, you can continue to remove fresh leaves until mid or late summer. Plants planted later in the year can be harvested in the fall or winter for fresh, late season greens.
Brassica Oleracea plants can grow from early spring to the start of winter. The plants are capable of tolerating temperatures as low as 20 ℉. This cold hardy nature has led to the plants sometimes being called Winter Kale.
Selecting the right variety enables you to cut and enjoy fresh leaves throughout the year.
There is no perfect time to harvest kale plants. If you want young leaves, pick them when they are small. If you prefer larger leaves, allow them to grow on the plant a little longer before you begin cutting them.
Do not wait too long before you cut your leaves. Old leaves can become discolored and fall from the plant. If this happens, remove the leaves and discard them.
Discolored leaves can be placed on the compost heap. Once the old leaves have been removed you can continue to fresh harvest kale leaves from the plant.
During the height of summer the leaves can become bitter. To avoid this, harvest kale leaves when they are young in the spring and fall. In frost free climates you can harvest kale throughout the year.
You can harvest kale throughout the year.
How to Harvest Kale
All varieties of Brassica Oleracea can be harvested in the same way. However, how you cut away baby leaves is a little different to removing mature leaves.
In general it is best to wait until the plant is around 4 inches tall before cutting the leaves. While large leaves can be full of flavor, often smaller leaves are more tender.
How to Harvest Baby Leaves
Pinch off the individual leaves from the base of the stem. They can also be cut from the plant with garden scissors.
A quicker way to remove a usable handful of leaves is to grab a handful and cut with a knife 1 to 2 inches above the ground.
When choosing where to harvest your leaves, consider the growth point. On Brassica Oleracea plants this is the central portion where the stems converge and new growth emerges. To allow new growth to emerge you should harvest the stems above this point. This keeps the smaller leaves intact and able to develop.
How to Harvest Mature Leaves
To harvest kale when the leaves are more developed or mature, grasp the stem at the base of an outer leaf and pull down and away from the plant until it breaks away. You can also cut the leaves away.
Cut as many leaves as you need. Try to leave at least 5 central leaves on the plant. This enables photosynthesis to continue, allowing the plant to continue growing.
Do not remove the central or innermost leaves. It is from these that new growth emerges.
If you are growing your plants in a soft or loose soil, or if the plants are newly established, it is better to cut the leaves with a knife or scissors than pull them away. This helps to prevent accidental lifting of the plant or damage.
Harvest time also provides you with an excellent opportunity to get up close and check the plants for any signs of slug or aphid damage. Discard any damaged, discolored or infected leaves. If slugs are a regular irritant in your garden, our guide to getting rid of garden slugs is packed with useful tips.
After the first harvest, allow the next set of leaves to grow to full size, roughly the size of an adult hand, before cutting away any more leaves.
Depending on the time of year and growing zone you can expect to harvest kale leaves once every 1 to 3 weeks. Continue to harvest kale plants for as long as they remain productive. This can be until the first frosts or snow of the year.
Allow the leaves to grow and develop before cutting.
How to Store Leaves
If you don’t want to use your kale harvest immediately you need to know how to store the plants. Correctly storing the leaves extends their lifespan, enabling you to enjoy the fruits of your labor for longer.
Wash the leaves before using.
To store fresh leaves, wash and then blot dry with a cloth. Once dried they can be stored in a resealable plastic bag. Place a kitchen or paper towel in the bag to absorb excess moisture. This prevents the leaves from becoming soggy or slimy.
You can now place the leaves in the refrigerator where they keep fresh for around 2 weeks.
You can rehydrate the leaves before using, by placing them in a bowl of lukewarm water for around 10 minutes.
How to Freeze Excess Leaves
Freezing the leaves enables you to store them for longer. It is a good way to store any excess leaves that you harvest.
Wash the leaves in cold water, removing any soil or dirt that you find.
Blanch the leaves for 2 minutes in a saucepan filled with boiling water before immediately cooling in a bowl of ice cold water. This step is not strictly necessary. However, if you choose not to blanch the leaves you will need to separate the stems from the leaves at a later point.
Not blanching the kale leaves can cause them to become bitter. It may also not keep as long.
Dry the leaves with paper towels or a OXO Good Grips Salad Spinner if you have one. The leaves must be as dry as possible before you freeze them. Freezing wet leaves can cause them to become bitter.
Once dry, remove the woody stems with a sharp knife. Remove as much of the stem as possible.
If you haven’t blanched the leaves you will also need to remove the portion of the stem that runs up the center of the leaf. This can be done by folding the leaf in half along the stem and cutting away the stem.
Chop or tear the remaining leaf into smaller pieces.
Remove the stems before freezing.
Spread out the leaf pieces on a large baking tray and freeze until solid. This usually takes 1 to 2 hours.
The frozen pieces can then be stored in an airtight bag and returned to the freezer. Squeeze out as much excess air as possible before sealing in Hefty Slider Freezer Bags.
Freezing the leaf pieces separately enables you to easily separate and use small pieces without having to defrost a large clump. If you want to store a large batch of leaf pieces, place them together in a sealable freezer bag.
Kale leaves keep in the freezer for up to one year.
Before using the leaves, thaw them in a refrigerator for 1 hour.
Brassica Oleracea Care Tips
Brassica Oleracea is often grouped with cooking greens such as collards, swiss chard and mustard.
While green leaved varieties are most commonly grown, you can also find purple and ornamental plants. Plant in a full sun position. If you are growing in a warm climate, planting somewhere with a little afternoon shade can help to prevent bolt.
The plants grow best in a sunny spot.
Other ways to prevent bolt include directly sowing the seeds into their final growing position and warming the garden soil with plant covers such as Happybuy Geotextile Fabric before planting. A number of bolt resistant varieties are also available, these include:
- Red Ursa,
- Premier or Early Hanover.
Allowing the plants to bolt can impair the flavor.
These plants do best in an organic rich soil. Before planting or sowing the seeds work in lots of compost.
You can grow kale in pots, beds and even indoors as long as you use well draining potting soil and can provide the plants with enough light. When growing indoors, you can supplement natural light levels with artificial grow lights.
Most varieties can be planted 3 to 5 weeks before the last frost date. With the right care it takes around 3 months for the plants to mature if you are growing from seed. You can start to take cuttings and harvest kale leaves in as little as 28 days.
A cool weather loving crop, in USDA Zones 8 and warmer you can plant in early fall for a late fall or winter harvest.
This is an easy to care for plant.
Watering the plants regularly encourages healthy growth. Try to keep the soil evenly moist but not soggy. Moist soil and cool temperatures encourages the plants to produce crisp, sweet leaves.
Mulching the soil around the plants helps to keep the soil cool. Do not allow the mulch to contact the base of the plant. This can encourage disease or infestation.
Fertilize the plants regularly throughout the growing season with a nitrogen rich or vegetable fertilizer such as Dr Earth Vegetable and Herb Fertilizer.
Regularly check your growing plants for signs of disease or infestation. A number of common garden pests can target kale plants, these include:
- Cabbage Looper,
- Flea Beetles,
Infestations can be treated with an application of homemade insecticidal soap. Black rot and club rot can also affect the plants.
Check the leaves for signs of infestation.
Different Varieties to Grow
Kale plants are typically divided into curly leaf and flat leaf types.
Curly leaf types, which include Siberian and Scarlet, tend to last longer in the cold.
Flat leaf types, which include Red Russian and Tronchuda, are usually quicker to establish in their planting position and start growing.
You can also find Bump Leaf varieties. Also known as Lacinato or Dinosaur, varieties include Nero Di Toscana Cabbage and Black Magic.
Some of the most popular types of kale include:
- Lacinato, a puckered heirloom variety that is originally from Tuscany. A hardy plant, Lacinato’s thick leaves remain edible even after snowfall.
- Red Russian produces smooth, tender leaves with attractive purple veins and edges. Red Russian is a sweet variety.
- Vates, a dwarf type that is ideal for growing in pots. Producing blue-green leaves, this curly leaf plant is pleasingly cold tolerant.
- Hanover Salad is a fast growing variety. A good choice if you want to enjoy an early crop of leaves, Hanover Salad has a pleasant flavor even when eaten raw.
This is an easy to grow plant.
An easy to grow addition to the vegetable garden, knowing how to harvest kale is a vital part of correctly caring for these leafy green plants.
Jen is a master gardener, interior designer and home improvement expert. She has completed many home improvement, decor and remodeling projects with her family over the past 10 years on their 4,500 sf Victorian house. She is also a passionate farmer who keeps goats, chickens, turkeys cows and pigs on her farm, and an instructor for her community’s Organic and Sustainable Farming project.