Growing Tatties

We thought we ought to take another look at this often overlooked vegetable. Potatoes are so rich in starch that it ranks as the world’s fourth most important food crop, after maize, wheat and rice and it is easily grown in both East Lothian’s lighter soils and West Lothian’s heavier soils.

The potato (Solanum tuberosum) originated in the Andes of South America, 8000 years ago. Today, potatoes are grown on an estimated 19,500,000 hectares around the world. The word ‘potato’ known in Spanish as ‘patata’ is derived from the word ‘batata’. China is now the biggest potato producer, and almost a third of all potatoes are harvested in China and India alone. The UK is the 11th largest potato producing country and we each eat 94kg of potatoes every year.

The famine caused by blight in 1845 and 1846 led to the development of new varieties with increased blight resistance, particularly in the USA and Scotland. A seed potato industry was started in Scotland where the climate kept the aphid vector of virus disease down to low levels – hence many names like Arran Pilot, Pentland Javelin etc. About 70% of British varieties were produced by Scots. The first government seed potato certification was established in Scotland and now operates from East Craigs, Edinburgh.

Growing
Potatoes require full sun to grow. Because so much of their growth takes place underground, they do best when planted in a light, loose, well-drained but moisture retentive soil, like East Lothian. They are, however, ideal for new gardens because they give the ground a good clean out – or you do when you cultivate it. Potatoes prefer a slightly acid soil with a pH of 5.8-6.5 and plenty of manure.

There are several different varieties of potatoes to choose from. Ideally you would plant early potatoes, which grow quickly, and maincrop potatoes which will provide better yields and keep better. The most popular types are listed here.
Chitting
Three or four weeks before planting, rub off most of the sprouts, leaving one or two good ones, depending on the size of the potato. Set them in trays with the sprout end (rose end) facing upwards and leave them in a frost-free but coolish, light area.
Planting
Easter weekend was always the traditional time to plant potatoes but potatoes will not begin to grow until the soil temperature has reached 45 degrees F. If the soil is water logged, the seed potatoes will probably rot before they even get started. If you have enough room to grow potatoes for store, you can plant your maincrop potatoes as late as June.
A day or two before planting, cut any larger seed potatoes in half, making sure each half has a good sprout. The seed has time to form a callous over the cuts, so that it won’t rot. Earlies should be planted 300mm apart in rows 450mm apart and 100mm deep. Maincrops should be planted 350mm apart in rows 650mm apart and 100mm deep. Salad potatoes can be planted closer together and harvested while much smaller.
Dig trenches for the potatoes, set them out as above and cover the potatoes. As the sprouts emerge, keep mounding the soil around the plants to ensure the growing potatoes are never exposed to light. If this happens, they will turn green.
Cultivation
Keep the potato plants well watered, especially while they are in flower. When foliage dies back, the potatoes are almost ready, but will benefit from another week or two to mature, as they will still be growing. Once lifted, leave them out to dry for a day or two, unless the weather is wet, in which case, store in a dry, dark, airy place. Then store permanently in sacks or paper bags and keep them dry and cool. They should keep for three to six months.