If you grew cavolo nero this year, October is when it starts to pay you back. If you did not, this is the post to bookmark for May, because it is one of the most useful vegetables you can grow in an Irish garden.

Cavolo nero is Tuscan black kale. The leaves are long, narrow, dark green nearly to black, and deeply blistered. It is cooked slowly in soups and stews all over Italy in winter. In Ireland it has one big advantage: it is tough. Wind, rain and frost do not bother it, and the cold makes it better.

Why frost makes it taste better

The seed packet information for our cavolo nero says it plainly: the flavour improves markedly after a frost. When the temperature drops, the plant turns some of its starch into sugar to protect its leaves. The result is a leaf that is sweeter and more tender than the same leaf picked in September. You do not have to protect it or fuss over it. You wait for the first cold nights, then you pick.

The same is true of the two cabbages in this post: the savoy and the red cabbage both sweeten in the cold.

When to sow cavolo nero in Ireland

This is the part to write in your diary now. Sow cavolo nero from May to July, in modules or trays, about 1 to 1.5 cm deep. Seed germinates in 7 to 12 days at 10 to 20°C. Transplant when the seedlings are 15 to 20 cm tall, 45 to 50 cm apart. You can also sow straight into the bed where it will grow and thin it out.

Sowing in May to July is what gives you plants that are large enough to stand through winter. Sown now, in October, it is too late. Save your packet for next summer.

How to pick it so it keeps going

Pick individual leaves from the bottom of the plant upwards, and always leave the crown at the top. The plant keeps making new leaves from the top, so one plant feeds a household for months. Plants reach 60 to 90 cm. They do not need staking unless the site is very exposed.

Two practical points:

• Pick leaves when you need them, not all at once. Cavolo nero stays in the ground better than it does in the fridge.
• Wash the leaves just before you cook. The blistered surface holds grit and the odd slug.

Two more winter brassicas worth planning for

If you have space for more than one, these are the two to add:

• Savoy Cabbage Invernale Mantovano: a very cold-hardy winter savoy with large dense heads and thick crinkled leaves. Sow May to July. It takes 110 to 140 days, so it is a long crop, but it stays in the ground all winter and the flavour sweetens after cold weather. The crinkled leaves soften beautifully in soups and slow braises, and they are good for stuffing.
• Red Cabbage Tête Noire 3: firm, dense, deep-coloured heads, frost resistant, harvested October to February. Sow May to the end of July. It stores well, and braised slowly with apple and red wine vinegar it is a proper winter side dish.

If you like cauliflower, Verona Tardivo is the late-winter heritage variety: sow in spring, transplant in early summer, harvest November to February.

From garden to table: cavolo nero, white bean and bread soup

This is a one-pot winter soup. Quantities are for four.

1. Soften one chopped onion, a carrot and a stick of celery in olive oil for ten minutes.
2. Add two cloves of garlic and a pinch of chilli, then one tin of chopped tomatoes. Cook for five minutes.
3. Strip the stalks from a big bunch of cavolo nero, chop the leaves roughly, and add them with 750 ml of stock and two tins of white beans (cannellini or similar).
4. Simmer for 30 minutes, until the leaves are completely soft.
5. Tear in two or three slices of stale bread and stir for a minute. Serve with olive oil and black pepper.

It is better the next day. It freezes well. The leaves are exactly the ones you pick from the garden on the day.

Your plan for next year

1. February to April: order and note your packets.
2. May to July: sow cavolo nero, savoy and red cabbage in modules.
3. June to August: transplant out and net against pigeons and cabbage white butterfly.
4. October to February: pick, cook and wait for the frost.

If you want to see the full month-by-month picture, the Irish kitchen garden calendar lays it out.

One packet to start

Cavolo Nero Lacinato di Toscana, €3.50. One packet is plenty for a family and a few neighbours. Free delivery across Ireland on orders over €40.

BloomySeeds is an Irish stockist of Franchi Sementi seed, Bergamo, est. 1783. Seeds posted from Co. Longford by An Post.

This article was drafted with the help of AI and reviewed and edited by the BloomySeeds team.