The kale pictured here was planted last autumn, in Sept 2020, so it’s just over a year old and still going strong. You can really get a lot from one planting, and we’d expect to keep harvesting this one through to next spring, so about 18 months total.
Autumn plantings of cavolo nero will tend to last for a year and a half, as they won’t reach full maturity in their first spring, whereas spring plantings are more likely to last just 12 months as they’ll reach maturity sooner, in the spring after being planted.
When mature, these kale plants will produce little broccoli-like sprouts. If you can afford the space, it is well worth letting them grow on and on until they do produce these sprouts. To keep them going for as long as possible, harvest the medium sized leaves regularly by tugging them sharply downwards off the stalk – leave the larger, lower leaves as these fuel the plant’s growth, and leave the smaller central leaves to harvest later on. If you need the space and are not able to keep them in the ground this long, then you can harvest an entire plant at one time. Just cut the stalk with secateurs and dig up the roots to put on the compost pile.
Watch out for common pests throughout the growing season – caterpillars, slugs, snails and pigeon damage. Some mesh netting is advisable during the summer when cabbage white butterflies are active, and when plants are young and vulnerable to pigeons!!