Of cabbages and kings...

January King cabbage
January King cabbage
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Last week I started the botanical ball rolling with common vegetables – including a photo of some show winning Daucus carota (carrots), Beta vulgaris (beetroot), Solanum tuberosum (potatoes) and Phaseolus coccineus (runner beans).

It is so important to be able to identify and correctly name the plants in our gardens, and we do spend quite a time ensuring our students are comfortable with this. We cannot move forward and learn about pruning or propagation if we do not know what a plant is called.

Wild cabbage

Wild cabbage

But as well as knowing the name of a plant and how to identify it, we encourage our students to really look at the plant. We take so much for granted, especially on plants we think we know, but it is good to find out a bit more about them.

For example, grey or silvery leaved plants are telling us they would like to be planted somewhere dry and sunny, whilst golden or blue foliaged plants prefer shade. Small narrow or needle-like leaves are adapted for harsh wind conditions, whilst larger leaved plants would be torn to shreds if planted in exposed open sites.

Going back to the vegetables – which we take for granted – what are we eating? Leaves, stems, buds, roots, flowers? Why is it edible?

Many of our vegetables are actually biennials – meaning that they would normally have a life cycle over two years. So in the first year, they germinate and grow lots of leaves – this is the juvenile stage. They then wait until the following year to flower and fruit – the adult stage. Then they die. But we do not let them reach this second year.

Our carrots, beetroot, leeks and many more are harvested at the end of their juvenile stage – when they have built up a good store of food to see them over winter ready for adulthood. Some store their food in swollen tap roots, others in the stem.

We have developed some species over thousands of years in order to make ‘different’ vegetables. Brassica oleracea is a ‘wild cabbage’ or wild mustard plant which commonly grows in limestone coastal areas around the Mediterranean. As a biennial, it stores reserves of food in a rosette of leaves over winter, before producing a spike of yellow flowers in the second year before dying.

Enterprising farmers have selected and improved plants with various attributes to develop many different forms. So good leafy forms have been developed to form kale, whilst for cauliflower and broccoli we eat the flower buds. A swollen stem is the edible part of the Kohlrabi; Brussels sprouts are lateral leaf buds, whilst our cabbages are the main, terminal leaf bud or growing point of a young, or juvenile, plant.

But as these are all botanically the same species as they are inter-fertile – capable of cross pollination and producing fertile offspring. This does mean, though, that it is not really worth saving your own seed of brassicas as it will not come true to type.

- Manea School of Gardening (RHS Approved Centre)

RHS Courses taught at all levels. Limited places left for the courses commencing in September. Re-open for plant sales on Saturday.