Types of Potato: There are three groups of potatoes: First Earlies, Second Earlies and Maincrop, indicating how long they take to grow and how far apart they need to be planted. First Earlies tend to avoid pests and diseases better (e.g. blight) but usually don’t store well and have a lower yield. Maincrops usually store best and have the heaviest yield but take up more space in the garden and for longer. Second Earlies are somewhere between the two.
Chitting: Potatoes are damaged by frost, so need to be kept somewhere frost-free until the ground is a bit warmer (e.g. from mid-March onwards). To keep them in good condition, place them in a light, cool (approx. 10o C) but frost-free place. Egg boxes are a handy way of storing seed potatoes until you are ready to plant them – the end with the most ‘eyes’ pointing upwards. This means that the seed potatoes grow short, strong roots which can be left on when planted. (If you keep them somewhere dark, they will grow long pale roots which will snap off, and the potato will go soft sooner.) This process is known as ‘chitting’ but is not necessary if you are able to plant potatoes immediately.
Planting: Handle seed potatoes gently so as not to break off the stumpy roots. Choose a sunny, well drained site, away from frost pockets. Make a shallow trench (or individual holes) approx. 12cm / 5” deep and add a sprinkle of fertiliser e.g. Fish, Blood & Bone (organic) or Growmore (chemical). Home-made compost, well-rotted manure or (chemical-free) grass clippings can be used to enrich the soil.
Plant First Earlies between mid-March and early April 12” (30cm) apart in rows 24” (60cm) apart. Early plantings should be protected from frost e.g. with fleece, straw or newspaper. They take about 10 to 12 weeks until they are ready to harvest
Plant Second Earlies between early and mid-April 15” (40cm) apart in rows 30” (75cm) apart. They take about 13 weeks until they are ready to harvest.
Plant Maincrops between late April to May 18” (45cm) apart in rows 30” (75cm) apart. They take 20 weeks until they are ready to harvest.
If you are short of space, potatoes grow well in large containers. An old compost sack can be used: turn inside out, make drainage holes in the base, fill about 12” deep with compost, roll down the top of the bag, plant three medium sized tubers. Earth up potatoes by adding compost as they grow, up to a depth of about 18” / 45cm, unrolling the bag upwards as required.
Growing: Potatoes should be ‘earthed up’ several times as they grow i.e. soil from between the rows is raked up around the plant, leaving the top leaves just visible. This helps control weeds, stops potatoes peeking out of the soil and going green (and therefore poisonous), and helps protect from disease. Soil should be kept moist but not wet – remember to check potatoes grown in containers. Mulch can be used to conserve moisture.
Pests & Diseases: The most common problem is potato blight, a fungal disease, which causes dark blotches on leaves, plant collapse, and potatoes with sunken lesions, which may then turn into a foul-smelling mush. Blight spreads rapidly in warm, damp weather. Spores are washed down from infected leaves into the soil where they infect tubers. Infected leaves and tubers should be disposed of in the black bin, and not composted or left in the soil, as this will spread the disease.
Slugs can also be a problem, particularly in wet weather: slug pellets may be used, and harvesting the crop avoids potatoes being tunnelled into. Potato scab is a bacterial disease encouraged by warm dry weather and causes dry, brown patches on the surface of the potato: these don’t affect yield or taste and can be scraped off or peeled.
Harvesting: Potatoes are usually ready to harvest as soon as the flowers open (not all varieties flower), but maincrops can be left in the ground until foliage dies down. Having a bit of a rummage to check how they’re growing is one of the treats of growing potatoes! First earlies can be eaten as soon as you harvest them, but for maincrops, cut off the stems at ground level and remove them two weeks before you lift: this helps the potato skins to toughen up a little, which protects them during harvest. Harvest on a dry day if possible, remove excess soil, and store in a dark, cool but frost-free location, allowing air circulation e.g. in a paper sack under the stairs. Check monthly in case of any rotting. Do not store any damaged potatoes as these will rot. Remove all potatoes from the soil as any left behind (‘orphans’) may carry disease and will grow the following year.
Enjoy eating and sharing your harvest!!!