Nine star perennial broccoli (Brassica oleracea botrytis asparagoides)

Nine star perennial broccoli (Brassica oleracea botrytis aparagoides) is a hardy perennial plant from the Brassicaceae or Cruciferae family.

These are one of our favourite plants. They are very easy to grow and are much less work than the annual broccoli which has to be sown and grown again and again each year.

Growing perennial broccoli
These plants can be grown from seed in the spring in much the same way as annual broccoli plants. Once the plants are large enough they can be planted outside into a permanent position. They grow to about 50cm - 100cm high and can have a spread up to 100cm so leave enough room for them to grow. Be aware, they won't produce any broccoli (immature flower heads) in the first year because they flower the following spring/early summer.

Problems
The wood pigeons loved them, an occasional cabbage white butterfly paid a visit and the very cold winter of 2010-11 killed them off. On the face of it, this doesn't sound very promising. However, temperatures at that time often reached -8°C and snow laid on the ground for a very long time.

We must have thought these plants were worth growing as we replaced them last spring. These new plants are very healthy with plenty of leaves. They seem to be quite happy with the recent snowfall (see photo) although the temperature in the garden this year has only reached -4°C on odd nights.

The wood pigeons are getting wild bird seed so are less interested in these new plants. For anyone interested in home grown bird seed we buy ours from Vinehouse Farm who grow most of their own seed in the UK. 95% of the seed in the 'Mixed Seed Bird Food' is grown on their own farm in Spalding, Lincolnshire.

The only other thing we would say is make sure that all the flowering heads are picked off before the flowers fully open so that the plant doesn't put its energy into making flowers and seed heads. Also stake any plants that are leaning over as they won't be at their best if they are not given some support. The plants that grew straight didn't seem to need staking even in very windy weather conditions.

Edible parts
The flowering broccoli heads, stems and the leaves are edible raw or cooked. The seed can also be sprouted. The flowering heads form in the spring and have a really good flavour. There is one main head in the centre and then lots of smaller heads arranged around the edge of the plant which are really useful for salads. The stems might need peeling as the outer skin tends to get a bit tough. The leaves taste like cabbage and can be picked all year round which makes this really useful plant for winter greens. The broccoli heads and the leaves can be picked as a cut-and-come-again crop.

Benefits of perennial plants
Perennials save the gardener time and money with a one time only purchase and planting. Once plants are established they usually involve very little work to look after them. Perennials are usually far more resilient than annual plants and become adapted to their local environment. They build and protect the soil, providing a permanent (untilled) area encouraging beneficial insects and mycorrhizae. The leaves provide a canopy to prevent soil erosion and suppress unwanted plant growth. The roots and leaves decompose naturally providing a regular stream of organic material for the soil. The roots hold and store water and other nutrients which might otherwise be washed away. Perennials are also often available as a food source when annual short season crops have died down.

There are more perennial plants on the planet than any others. They live longer, storing more carbon than annual plants. Because they live longer, they produce more extensive root systems which are good at adding carbon to the soil. Research at Rothamsted shows that perennial vegetation contains 10-20 tonnes more C per hectare in the subsoil than arable crops (DEFRA, 2010).