Potatoes are useful as a cleaning-up crop, for after growing potatoes the ground is cleaner as during the growing period the tops grow large smothering out weeds.
Of course a great deal of preparation will have gone into the land, adding large quantities of manure and compost to guarantee a good potato yield, also the crop does not leave behind any detrimental residues so that it is ideal for any crop that is to follow.
Choosing which crop to plant:
Earlies: If you are working with a limited area, then you should concentrate on the earlier types. Because they are lifted earlier, they are less likely to encounter problems such as wireworms, slugs, and blight. Earlies are ready 15 – 16 weeks after planting about mid-June and July.
Second Earlies: Second Earlies take 16-17 weeks to mature after planting about June through to August
Maincrops: Maincrops are ready 18-20 weeks after planting August through to late September. These take up the most space in the garden, but they are the best varieties to store
Potatoes should be grown on deep, fertile soil that is well-drained and contains plenty of organic matter. Choose a sunny position in the garden but avoid exposed sites and frost pockets, these delay the developing foliage
Prepare the land the previous autumn dig down to a spades depth and leave it rough. In the spring during March or early April, prepare 4 in. (101mm) deep furrows and place in them some well-rotted manure and compost at the rate of a wheelbarrow full per sq. yard.
Sprinkle fish manure with a 6 percent potash evenly along the furrows at a rate of 3 oz. (90g) to the yard run. Do not add lime; potatoes dislike lime and its presence in the soil appears to encourage scab disease.
If you haven’t done the preparation at the suggested time, you can still go ahead, some rules can be broken and you can still grow a good crop if you prepare the land just before planting.
Plant potatoes that are the size of a hen’s egg, weighing about 2-¼ oz. (67g). Buy your tubers from a reputable seedsman, choosing those, which are virus-free. If the tubers are larger than 2-¼ oz. (67g) cut them into two, lengthways at planting time, but make sure that there are ‘eyes’ or shoots on each piece.
Start to prepare your potato seeds at the end of January or February by standing them in a tray with the majority of ‘eyes’ at the top, the practice is termed “chitting” it is done in order that the seed potatoes will shoot and get them off to a good start.
Place them closely together so that they remain standing in the same position. Store the trays in a frost-free shed, greenhouse or a cool room in the house where there is plenty of light. If more than two good strong shoots develop on each tuber, the extras should be carefully rubbed off.
The time for planting potatoes will depend on your area, in the south the middle of March is suitable but April is better in the north when the ground starts to warm up.
At the time the tubers are planted the two sprouts should be about 2 in. (50mm) long. Take great care not to knock off the shoots from the tubers, taking them separately from the box and placing them into the furrows carefully should help to safeguard any accidental damage at this stage.
- Plant Earlies 12 in. (30cm) apart in rows 16-20 in. (40-50cm) apart;
- Plant Second earlies 16 in. (40cm) apart in rows 30 in. (75cm.) apart;
- Plant Main-crops or Lates 16 in. (40cm) apart in rows 30 in. (75cm) apart.
Place the potatoes on the manure setting them into the trench with the shoots pointing upwards, in the furrows that are 3-5in. (76mm-127mm) deep, but the exact depth should vary according to the variety of potato you are planting. Cover each one with a small handful of grass mowings; this will help to keep away scab disease.
Do not reduce the suggested spacing between the rows, as then there will be no room to earth up as the top growth appears. Draw the soil into the planted furrows in such a way that a mound is left along each row.
Should the warning of frosts be given, any subsequent leaves that appear must be covered over with soil until the threat of frost has passed; horticultural fleece is ideal for this purpose.
When the shoots appear, earth up each row by covering it with a ridge of soil so that the shoots are just buried; this must be done on a regular basis. The sides of the ridges should be at an angle of 45 deg. If they are steeper, the tubers may start to appear through the sides of the ridges; if they are flatter, the plants will not be sufficiently well covered. By the end of the growing season, the ridges will be about 6in. (15cm) high.
Earthing up is extremely important and though it may seem a tedious exercise is a vital part of growing potatoes. It protects the tubers from frost and reduces the number of green potatoes. As the plants grow and the fruits develop, the tubers tend to be pulled towards the surface, however, once they reach the surface and the light reaches them, they turn green and are inedible, becoming poisonous and only suitable for the compost heap.
Once the tubers have reached the size of marbles, it is particularly important that they have adequate water. Unless there is regular, ample rainfall, the size, and quality of the crop will be reduced.
Use the early potatoes as soon as they are large enough, a warm sunny day is best, but do not lift them if they are too small; they crop can double its weight in two weeks.
The first should be ready about June until September, depending on the variety and of course the weather. Maincrop varieties can be left in the ground much longer, until September, even though the haulms or stalks may well be looking past their best.
Cut off the haulms to ground level two weeks before you lift the crop, this will give the potato skins sufficient time to toughen up, making them easier to store.
As soon as the tubers are dry, you can store them in a cool but frost-free location. It is essential to store them in the dark, packed in either paper or Hessian sacks.
Pests and disease
Something to watch for is Potato Blight (phytophthora infestans) a particularly nasty disease that will ruin the cop. It is a common disease of the potato especially in warm, muggy seasons
Potato Blight: First symptoms are a dark brown patch and yellowing of the leaves, which then turn black, a white bloom then develops on the underside as the foliage dies. To help avoid this disease it is so important to use only certified seed, those that are produced in areas where the infection is not prevalent.
If the disease does attach your crop destroy any infected potatoes by burning them. Always make sure that all the crop is harvested do not allow any potatoes to remain in the soil after harvesting. Avoid overhead watering, which will wash spores down to the soil.
Always earth up well to protect the tubers. If after taking all the precautions this disease infests the crop, remove all the top-growth so that it does not spread to the tubers so that some may be saved.
Scab: Scab is especially prolific on light, sandy soils or those that have recently been limed or converted from grassland; this disease causes raised scabby patches on the potatoes skin.
To control this unpleasant condition, water regularly, improve the organic content of the soil before the next crop of potatoes are planted, and importantly do not lime prior to planting. Choose resistant varieties such as ‘Arran Comet’, ‘Arran Pilot’, ‘King Edward’ and ‘Maris Peer’.
If slugs and wireworm are a problem, lift the crop as soon as possible as these pets generally become more of a problem towards the end of the season