Farming Crops: Winter Vegetable Harvest
Vegetables such as carrots and turnips are so familiar that it is easy to forget they are actually roots — the hidden but vital parts of plants.
The root system plays an essential part in the growth and development of a plant; it anchors the plant firmly in the soil and is the pathway through which water, salts and other compounds are taken up. It also synthesises hormones, complex organic molecules, which are transported to the shoots and are vital for normal development. If its roots are restricted in their growth by poor stony soil, or by waterlogging, or by buildings, then the development of the plant is retarded and its growth stunted.
Roots as food
The root can, and often does, provide a store of food for the plant and many plants have been developed over the years to produce roots that will provide food for man and his animals. These plants come from a wide range of different families and include vegetables such as beetroots, carrots, horseradish, parsnips, salsify, swedes and turnips, with carrots, parsnips, swedes and turnips being the most widely grown.
All these vegetables are biennial; they develop swollen roots containing products stored from various metabolic processes, during the first year of growth. In the second year, they utilise the stored material to produce numerous flowers and, finally, seeds. Man intervenes before the second year, lifting his crop during the autumn and winter periods.
The parsley family
As well as the hemlock and the giant hogweed, the parsley family includes the carrot and the parsnip. Carrots have been cultivated for over 2000 years and are probably derived from western Asiatic forms of the species. Their ancestor, the wild carrot, grows all over the British Isles, and its large, yet delicate, flower heads have given it a variety of popular names, such as Queen Anne’s lace. Though not common here, white and yellow-rooted varieties of carrot are grown in some European countries, primarily for stock feed, while in India purple-rooted varieties are grown for human consumption.
Carrots grow best on deep, well-drained, stone-free sands and peats, where the roots can develop without restriction. They are sown in the field from February to May, for harvesting from July right through the following winter and spring. Alternatively, they can be sown in unheated greenhouses or plastic tunnels during the winter months, for a crop in the following February to June period.
The seed is drilled in rows and thinned to allow development of the elongated, swollen tap root. The dry matter in the roots consists primarily of sugars; but carotene, which is largely responsible for the colour, is also a valuable component since it is produced as part of the process of manufacturing vitamin A by the plant. The familiar red or orange varieties are grown either for direct human consumption, or for canning.
Often the earliest vegetable to be sown outside the greenhouse, parsnips are not harvested until the following winter, which allows the roots to develop in the ground for almost a year. They should be dug up by February if required as a vegetable, since they begin to develop new leaves and use up their stored food reserves after that.
Because they stay in the soil for such a long time, other quicker-growing vegetables such as lettuce or radish are often grown between the parsnip plants, thus making rather more use of the space they take up. However, this may limit the growth of the parsnip, and this in conjunction with its low seedrate means that it has a rather limited capacity as a winter vegetable.
Relatives of the cabbage
The turnip is a member of the cabbage family, and is related to the cauliflower, Brussels sprout and sprouting broccoli. Unlike these latter vegetables whose flowers and leaves are the main source of food, the swollen bulbous base of the stem and the upper section of the root provide the edible part.
Commercially, turnips are a market garden crop. The principal growing areas are in Worcestershire, Bedfordshire, Surrey, Sussex and Kent.
Turnips have recently gained a new lease of life for two reasons. Firstly, their use in stew-packs with carrots, onions and other vegetables has made them very popular in the frozen vegetable market. Secondly, farmers often sow turnip seed after a cereal crop so that cows and sheep can graze on the tops in the autumn
The swede is also a member of the cabbage family. It is thought by some to be of hybrid origin between certain races of cabbages and turnips where the two species overlapped in their original habitat (from western Europe to eastern Asia). Man’s selection of desirable types over many hundreds of years is responsible for the form of the swede today.
Swedes are widely grown in this country, mainly in the wetter areas of Devon, Somerset, Yorkshire, Lincolnshire and Lancashire. Most of the harvesting is done manually, commencing in September and ending in the following May. During periods of hard frost (when prices are high) a reserve supply of roots can be stored in open sheds.
The estimated area of land upon which turnips and swedes are grown in England, Scotland and Wales is approximately 51,000 hectares (126,000 acres) in total.