I was wandering around Waterstones bookshop on a visit to Cambridge last month when my eye fell on a copy of Martin Crawford’s book “How to Grow Perennial Vegetables” (2012). It was the words “low-maintenance” on the front cover which attracted my attention. Ever one to save effort where possible, I bought it. And developed my latest craze.

Perennial vegetables and fruits can be defined as edible plants that live for at least three years and can be harvested without killing the whole plant. Some plants are perennial in warm climates, but not in cooler ones, therefore do not count as perennials in Europe.  Many perennial vegetables we don’t usually hear of are an important part of diets around the world, for example the ulluco  (Ullucus tuberosus), a root crop apparently second in importance only to the potato in the Andes.

Perennials are said to contain more nutrients on average than annual vegetables, and to be better for the environment since you don’t have to disturb the soil so often, although you do have to get rid of weeds as soon as possible. Since they are usually allowed to flower, they are good for pollinating insects, which are currently under threat. Harvesting tends to extend over a longer period of the year, so they are useful during the traditional ‘hungry gap’ in spring, when you have used up your stored crops but the new ones are not yet producing anything. The root system of perennials is ready to start growing in early spring, so it makes the best use of a short growing season.

They do have some disadvantages, especially for large-scale commercial growers. They are harder to weed around by chemical or mechanized means. Crop yields are lower, since the vegetable has to use some of its energy keeping its root system going for next year, and they take longer to establish. And they are just as prone to diseases like club root as annuals, which is why I am regretfully not going to try any of the perennial cabbages, although they sound great (my main bed is infected with clubroot). The fact that they are not rotated like annual crops, but remain in the same bed for years can make this problem worse. 

The commonest perennial vegetables currently grown in Orkney are rhubarb and globe artichoke, and soft fruits like currants, gooseberries and berries. Most gardeners up here grow rhubarb, and if you don’t, there are often feral rhubarb plants available, like the ones at a beach near me. (It’s a pity that I can’t eat rhubarb any more myself).  I recently visited a garden on Hoy where they have planted asparagus. I have a sorrel plant which is fast becoming established and producing useful quantities of leaves. A local grocer was selling ramsons (wild garlic) in pots this spring, so I bought one.  

Watercress (Nasturtium officinale) is also worth trying. Apparently you do not need a fast-running stream to grow watercress; you can grow it in a container and keep the compost moist by standing it in a saucer full of water. The saucer needs to be emptied and the pot flushed through with clean water periodically to keep it fresh. That's also a good idea from the midge point of view as well. They breed in stagnant water and they don't need much encouragement up here.   You can grow watercress from seed, or you can do what I have done. Next time you buy a bunch, put some sprigs in a jar of water on the windowsill. Hopefully it will grow little roots in a week as mint does, and can then be planted out.   

The various blogs about perennial vegetables which have appeared in recent years also mention wild plants usually regarded as weeds. My garden, like everybody else’s, goes yellow with dandelions in early summer. I have no objection to eating dandelion leaves in salad or young nettle tops in soup. I can’t be bothered with Good King Henry, though. As a young archaeologist, I naturally tried a variety of wild greens such Good King Henry and Fat Hen and found them stringy and just tasting vaguely of greens, while ground elder I found had a positively objectionable tang.

Silverweed (Potentilla anserina) grows prolifically in Orkney and the thin roots were used as a famine food in the past.  The roots are small and spindly in the wild and it takes a lot of effort to collect enough for a meal (Milliken & Bridgewater 2013 pages 47-49).  However, F. Marian McNeill (2010, page 229) quotes Alexander Carmichael (Carmina Gadelica Vol. IV) as recording that before the introduction of potatoes, silverweed was cultivated in the Highlands and Islands and grew quite large. It was sometimes boiled, or sometimes the ground-up roots were made into porridge or bread.  She gives a recipe for Silverweed Bannock which is not a famine recipe. You are supposed to go over a ploughed field in spring to collect the long thin white roots, dry them and grind them up, and then make a bannock by mixing them with oat or barley meal, butter and warm milk and cooking them like a scone or an oatcake. It is said to taste nice but not as if it has much potential as a future staple crop.

What I am going to try next is skirret (Sium sisarum), known as crummock or crumag (Gaelic) in Scotland. I have bought two plants from a fascinating small firm in Devon. Skirret is a root crop with a sweet taste something between a carrot and a parsnip. Various European countries know it under the name of sugar root because of its sweetness.  It seems to be very popular at the moment and it does seem to have interesting possibilities. It doesn’t mind a cold climate and grows well in Britain and Northern Europe; it is resistant to disease, although it grows fibrous if it doesn’t get enough water.

 Skirret originated in China and was introduced to Britain by the Romans. It was cultivated thereafter for centuries. The 14^th  century English recipe collection known as the ‘Forme of Curye’ gives a recipe for fritters made of parsnips (‘pasternakes’), skirrets (the spelling varies wildly)and apples: these are dipped in batter made of flour, eggs, ale, saffron and salt and fried in oil or ‘grece’. They were served with almond milk. (I am going to try that one). Skirrets were a favourite in Tudor and Stuart times, and were planted in the royal kitchen gardens laid out by Queen Anne in 1702 at Hampton Court Palace. According to Geddes (1994, page 37), the recipe book of Katharine Bruce, Lady Saltoun, married to a late 17^th century Scottish laird, has a recipe for boiled chicken stuffed with parsley and surrounded by vegetables such as boiled artichoke hearts or skirrets in a sauce. Skirrets were being grown in Shetland gardens by the end of the 17^th century (Fenton (1978 page 421). But by the late 17^th century, potatoes were being grown in Britain in significant quantities. Potatoes are easier to peel, as skirret roots are long, thin and uneven, and they are easier to harvest industrially. Sugar was more widely available too, so the sweet taste was less important. The skirret gradually fell out of fashion.

Perennial vegetables are not totally labour-free. You still need to weed them, feed them, and keep them well-watered, especially if you are growing them in containers or a restricted space like a small raised bed. I seem to have spent most of my garden time this summer, which has been unusually dry in Orkney, pouring water onto my vegetables. My water butt has run dry twice. And I won't know until next summer whether my artichokes, skirrets and watercress are going to survive and produce an edible crop, whereas this year's potatoes have been great, in spite of the drought. We'll just have to see….

F. Marian McNeill 2010 “The Scots Kitchen. Its Traditions and Lore with Old-Time Recipes”

William Milliken & Sam Bridgewater  2013 “Flora Celtica. Plants and People in Scotland”

Alexander Fenton 1978 “The Northern Isles: Orkney and Shetland”

Olive M. Geddes  1994 “The Laird’s Kitchen. Three hundred Years of Food in Scotland”