Kale is a hardy vegetable and easy to grow outdoors
Photo: Kale ‘Nero Di Toscano’ (Organic) from Suttons
Kale is a versatile, nutrient-dense vegetable that is often called a superfood. This hardy brassica can be harvested as it leaves cut-and-come-again almost all year round and, with a flavor that is only enhanced by frost, it can keep you through the ‘hungry gap’ if there is little else in the season. We asked experienced allotment grower Lee Senior for his advice on growing kale. Here are his top tips.
Browse our full range of kale seeds for inspiration.
The best varieties of kale to try
There are so many different types of kale that there is something for everyone. Kale ‘Scarlet’ is my personal favorite – it looks and tastes the part! This variety has attractive crimson/purple leaves with a medium color that gives the plants a decorative appearance. It also freezes well.
The Italian variety ‘Black Magic’ has dark green leaves and is suitable for growing as a ‘cut and return’ plant. It has good cold weather tolerance and good resistance to rotting. During the long harvest, it will continue to plant from the beginning of September until the end of February.
If you are short on space, Kale ‘Dwarf Green Curled’ is the variety to go for as it is compact in height. This plant will be able to withstand anything winter throws at it and is a reliable crop from October until the end of March. I like to steam it to use as a nutritious winter vegetable. In short, this plant is a real toughie!
Finally, for something a little different, why not try the ‘Buttonhole Starmaker’ variant? This kale is not like the others, it has attractive pink veins. The plants resemble ornamental cabbages at first, although ‘Buttonhole Starmaker’ is completely edible and its mild, sweet flavor works well in stir-fries. If you don’t have a large veg patch or allotment, these varieties wouldn’t look out of place in a decorative flower bed!
How and when to sow kale seeds
This attractive pink color is sweet and soft
Photo: Kale ‘Buttonhole Starmaker’ seed from Suttons
Kale seeds are easy to grow and do not require special conditions. Temperatures of 15C-18C (59F-64F) are ideal. It takes about 28 weeks to reach full maturity, so it needs a long growing season.
I usually plant two. The first one is in the middle of March when I sow the seeds in a low temperature under the glass. I use small pots containing proprietary compost, to lightly cover the seeds and remove weak seedlings. Prune the seedlings at the 5 or 6 leaf stage after firming them up. Young leaves will be ready for small harvest from August onwards.
I also do sowing in late May or early June. At this time the seeds are sown outside in a well-ground and specially prepared planting area. I use a proprietary fertilizer to plan the seed holes and sow the seeds very thinly at a depth of 13mm (0.5 inch). The seeds should be kept moist until they germinate, which takes about 5-7 days. Small plants can be planted in their final position at the 4 or 5 leaf stage. This is my main winter plant to supplement the original planting.
When planting kale
This tender black kale plant can be harvested as a cut plant and regrown
Photo: Kale ‘Cobra’ F1 seed from Suttons
A useful property of kale is that it will tolerate partial shade and sunny parts of your allotment or vegetable patch. It is not very fussy about the location, but it is better to avoid windy or exposed areas.
It works best in well-drained soils that contain plenty of well-rotted organic matter. However, kale will also tolerate poor soil, although the resulting plants will not be as tall or as big.
When it comes to growing outdoors, remember that your plants need a lot of space to fully develop. Discard any weak transplants as you won’t need too many plants at any one time. I space my plants about 50cm (20 inches) apart. However, in smaller spaces, you can find spaces that are a little closer together.
I think curly kale looks really attractive with a bunch on it. You might consider growing some in a visible spot near a path or building, or as a focal point in a bed or container.
How to care for kale
This subspecies has attractive, black, strongly ribbed leaves that are incredibly strong
Photo: Kale ‘Dwarf Green Curled’ – Seed from Suttons
Stick your young plants into the soil really well when planting them in their final growth areas. Most species can reach a height of over 90cms (3ft) so, in humid climates, you may need to stake them with a bamboo frame to prevent them from leaning or falling over. Miniature varieties are shorter than this and are suitable for growing in large containers.
Water your plants well during dry weather.
Kale is part of the brassica clan and is one of the hardest winter crops. So it doesn’t need any protection, even in the worst frost. However, you may need to protect the plants from cabbage white butterflies and pigeons by covering them with fine netting.
Kale is a slow-growing plant that takes about 24 weeks to start planting and 28 weeks to reach maturity. This is something to keep in mind when planning to rotate your plants. The land will be available from mid-March when you finally dig the plants up.
Avoiding common problems
The deeply curled purple leaves of ‘Scarlet’ are rich in vitamins A & C
Photo: Kale ‘Scarlet’ seeds from Suttons
Cabbage white butterflies are a pest in mid and late summer. The adults burrow into all the brassicas and try to lay eggs that will eventually hatch into those predatory caterpillars we all know so well!
Cover the hoops with butterfly netting or a cage to prevent the adult from laying its eggs. Alternatively use the finger and thumb technique to collect and move, or destroy, small caterpillars as they emerge. This method works well if you don’t hide too much and if you can check the plants regularly.
Pigeons also have a penchant for all brassicas. They will eat the leaves, leaving the remains of bones. Protect the plants from these aerial attacks by covering them with netting. Affected plants may recover but subsequent growth and vigor will be reduced.
Clubroot is a fungal disease that affects brassicas. Try to choose a resistant variety if your soil contains fungus and you aim to keep the PH on the slightly alkaline side.
Finally, cabbage root flies are insects that lay their eggs on the bottom of the transplant containers of all brassicas. The resulting flies bite the roots, causing the plants to wither and become weak and useless. Protect your plants with well-sized discs around the stem to prevent eggs from being laid.
When to harvest kale
These sweet, white and green leaves can be planted in a vegetable patch or a decorative border
Image: Kale Seed (Borecole) F1 ‘White Peacock’ from Suttons
It is actually possible to harvest kale from the end of August to the end of March, which gives a planting time of about seven months. That’s what I call good value! Don’t forget that you can also use your small kale thinnings in salads instead of just throwing them away.
Kale can be considered a ‘cut and come back’ plant, a trick I use all the time. It’s best to grow more plants if you intend to do this, so you don’t rely too much on the same plants and weaken them. Taking a few leaves from each plant regularly does not stress them out unduly. Healthy plants will soon grow new leaves. In good seasons, I start taking a few leaves from August onwards and leave the plants to recover for a few weeks before repeating throughout the Autumn.
To harvest kale, simply pinch the leaves off the main stem. They should be easy to separate and clean.
Finally, for something very different, why not grow kale on the windowsill? Young, young kale seedlings grow well on a windowsill during the winter months as a healthy, fast-growing green snack. The seeds germinate within a few days in a shallow seed tray where they can be planted without replanting. Keep the tray moist and avoid strong sunlight. Harvest the seedlings with scissors within 7-21 days.
Kale is a healthy, decorative plant that provides an almost year-round supply of leaves. Smoked, roasted, added to salads, battered in pesto, baked in cream or added to smoothies - a must-have plant for any garden. For more of Lee's practical, hands-on, vegetable-growing tips, head over to her monthly share pages.
