'Cavolo Nero' or 'Nero Di Toscana' is the only kale grown in Italy, simply because it is by far the best tasting kale. Its large strap like leaves are fantastic in a stir fry with excellent taste and strong dark green colour. Kale is a nutritional powerhouse with powerful antioxidant properties and is also anti-inflammatory. Ideal for successive cutting it keeps on producing tender leaves for months on end.
Where to grow kale:
There is an ideal soil and site for Kale but rest assured, it will grow in almost all conditions, even part shade and sandy soils will produce a reasonable crop. For the ultimate crop, grow in a soil that was enriched with compost or manure the previous season. Full sun is best but they will grow well in part shade.
When to grow kale:
With the exception of rape kale, sow the seeds in a seed bed around April to May time. The timing is not crucial because kale will germinate in temperatures as low as 5°C / 42°F and as high as 35°C / 95°F. That's an enormous range for any vegetable.
Sow the kale seeds about 1.5cm (½in) deep in rows which are 22cm (9in) apart. germination will take about 10 days. When the plant is about 22cm / 9in high and four leaves have developed (about 6 weeks after sowing) transplant them to their final positions.
Seeded or transplanted kale should be spaced 6 inches between plants in the row with rows 1 foot apart.
Make a hole with a dibber or suitable stick (A piece of an old broom handle is ideal). Place the seedling plug in the hole and firm gently around the roots, water well. Kale should be planted slightly deeper than they grew in the seed bed. Spacings are 45cm / 18in apart with rows the same distance apart.
I recommend sowing Kale in modular trays, you will find the plants establish better and it's far easier than growing in a seed bed. Why?
- Excellent crop establishment
- Uniform plant development
- Quick transplanting with minimum root disturbance
- Gives the plant a head start against weather and garden pests and diseases.
Sowing in Modular Trays
Use a seed compost which has a finer texture and lower nutrients than your standard multipurpose compost. We use a seed module tray with each section being approx 2 inches deep. Here's what you do:
- Fill the seed tray with compost and brush off any excess. When filling the tray rub the compost through your hands to break up any lumps. Give the tray a sharp bang on your table to settle.
- With your fingers make small depressions in each cell about a fingernail or 2 cm deep.
- Sow 1 seed per module.
- Cover the seeds with another layer of compost then scrape across the top of the tray with a stick to remove excess.
- Gently water your seeds. A good tip is to use a plastic bottle with small holes punched in the cap. This is less likely to wash the seed around than the heavy spray from a watering can.
- Place your trays in your greenhouse, polytunnel, cold frame or windowsill to germinate. They should be ready to plant out in about 4 weeks.
Hardening Off Kale Seedlings
Plants that have been raised indoors will need to get used to the outdoor temperature and conditions before they can be planted outside, this will take about a week to 10 days depending on the weather.
The best way is to use a cloche or mini greenhouse. You can leave the cloche off the plants on dry frost free days and replace at night. Gradually increase the time with the cloche removed until the end of the week when you leave it off day and night.
If the weather is mild you may not need the cloche, just move the plants outside for longer periods each day.
If you have started your seeds on a windowsill you will need to leave them in an unheated room for a day or two before moving outside to the cloche.
Caring for your crop
Almost no care is required because these are one of the strongest and most disease resistant of all vegetables. Remove yellowing leaves which will appear round the base of plant. Keep the weeds under control with regular hoeing.
Dwarf varieties of kale (see curly / crinkly kale to the right) will withstand winter winds especially well.
The spacing for Kale is 60cm between plants and 50cm between rows.
Water your seedlings well an hour or so before transplanting. To plant, make a hole in the soil the approximate size of the seedling 'plug', try not to dig up too much of the surrounding soil. You need to push the soil in around the roots firmly with your fingers to get good contact with the soil.
Water the plants after planting but do not soak them. You are better to transplant on a dull day or in the evening to prevent the plants wilting on a hot, dry day.
Keep watered if conditions are dry although kale is much more forgiving than any of the other brassicas.
Kale will benefit from a sprinkle of poultry manure spread widely around the roots. Our 'Seamungus' seaweed-chicken manure pellets are an excellent source of nitrogen which will be perfect for leafy crops like kale. If you want to give the plant a quick boost a liquid seaweed feed is ideal.
Hoe regularly to control weeds and to stimulate the growth of the plant. One of the best gardening tools you'll ever buy is the oscillating stirrup hoe. It's a very effective old fashioned tool that really works properly.
Hoeing not only removes the weeds but it also breaks up the surface of the soil and creates a fine texture or 'tilth'. A good tilth lets air and moisture in to the soil, microbial activity is increased which then feeds nutrients to the roots of your plants.
Removing dead leaves
Remove any yellow, discoloured leaves from the plant as they may harbour disease which will spread to your crop.
Pest and Disease Control
Kale suffers the usual brassica pests and diseases but to a far lesser extent.
I don't want to put you off but there are a couple of things you'll need to look out for when you've planted your seedlings. Sprouts belong to the cabbage or Brassica family so all the same pests and diseases apply as cabbage. As with so many things, prevention is better than cure so here we go:
Cabbage root fly
Cabbage root fly is a small grey fly a bit like a small house fly. It lays it's eggs at the base of cabbage seedlings, the eggs hatch into maggots and then burrow down to feast on the new roots of your plants.
Young plants will begin to wilt and eventually stop growing. The leaves will start to take on a blue\green colour. If you bite the bullrt and pull up the plant you will see white maggots tucking into the roots.
The best organic method of control is to cover your calabrese with bionet (micromesh) to stop the fly laying it's eggs. Make sure the net is sealed all the way round to prevent access by the fly.
Cabbage collars. You can either buy or make these yourself from roofing felt or carpet underlay.
The collars are a circle of material covering the soil around the base of the plant which helps prevent the root fly laying its eggs around the stem and stops the maggots burrowing down to the roots.
Nematodes. These are naturally occuring microscopic worm which attacks the larvae of the cabbage root fly. The nematodes are in your garden soil anyway you're just increasing the numbers. It is a non chemical product so is safe for use around pets and children. You will need to do a couple of applications but in my opinion it's well worth it as you'll also protect a whole host of other crops.
Cabbage White Caterpillars.
The caterpillars of the cabbage white butterfly will reduce your plants to a skeleton within a couple of days so clearly it's best to keep on top of them. Look out for the yellow eggs of the butterfly under the leaves and brush them off. It's much easier to remove the eggs than the caterpillars so this is well worth doing. The caterpillars in the photo are babies, they'll get a lot bigger and do a lot more damage if you let them!
The best and easiest method however is to cover your crop with bionet as with root fly.
The Cabbage whitefly is an aphid (Like a greenfly, except white), it is less troublesome than other cabbage pests but worth keeping an eye on. The adults are tiny white insects which you'll find on the underside of the leaves. They produce a sticky substance called 'honeydew' which will probably cause a grey mould later.
Remove any yellowing leaves at the base of the plant as they may be harboring aphid eggs. You can wash off whitefly, honeydew and grey mould with a strong jet of water.
Clubroot is one of the most tricky diseases you'll encounter in the garden but with proper precautions it can be successfully controlled. If you start a new vegetable garden the chances of having clubroot are pretty slim and you can prevent it entering quite easily. If you do get clubroot the cysts survive for up to 9 years in the soil. You won't be able to grow any of the cabbage family (Brassicas) until it's gone so you've been warned!
The disease usually arrives in your garden through infected transplants or by walking from infected soil into a virgin patch. If you have an isolated garden you are unlikely to get it whereas you need to be more careful in established allotments.
Poor growth with wilting leaves of a reddish-purple colour. If you pull up the roots you'll see swollen, knobbly deformed growth with a pungent foul odour. In more advanced cases the roots will have dissolved into a slimy pulp.
If you have clubroot already seek out varieties with resistance to the disease, this will be clearly marked as an advantage on the pack.
Otherwise you'll just have to live with it, you can minimise it's effects by doing the following:
- Not composting your brassica roots, burn them.
- Don't sow brassica famiy green manure. (Mustard, Rape)
- Start your plants in modules. (I'd recommend that anyway).
- Lime the soil the previous Autumn to make it more alkaline (Clubroot likes acid conditions).
- Grow in raised beds as clubroot likes wet conditions.
Cabbage White Butterfly
Remember to keep an eye out for cabbage white butterfly eggs on your kale plants. Look under the leaves for the little yellow eggs and brush them off.
It is much easier to cover your crops with micromesh (enviromesh) if you haven't done so already. Make sure no butterfly gets in while you're doing it!
They provide a crop between late September to early May.
Harvest the bottom leaves first, the top of the plant will continue to grow and produce new leaves. Larger, mature leaves have a bitter taste so it's best to remove them for the compost bin. This will stimulate the plant to produce more young tender leaves. Harvest kale only when you need it because it does not keep well even in the fridge.
You can harvest a number of leaves in one go but make sure 8 or so remain to give the plant energy to grow on. Pull the leaves off the plant with a sharp downward tug. Remove any yellow or damaged leaves to keep the plant healthy. As you harvest Kale and it continues to grow the plant will end up with a tall stem with foliage on the top. Earth up the stems and tread in firmly to prevent them blowing over on windy winter days.