Potatoes have a fairly wide range of minor pests and one or two major pests. Reasonable rotation of crops in the garden is important to keep the pest numbers down to manageable levels. Pests specific to potatoes have a limited survival time, if they do not have access to potatoes. Ideally the same part of the garden should only be planted with seed potatoes once every seven years. However this may not be practical, so it is possible to go down to once every four years, although potato pests may become more of a problem. It is best to develop the longest rotational system you can for your garden.
Soil Preparation & traditional planting
This depends on the condition of your soil and on our physical abilities. Ideally seed potatoes like well-dug, deep soils, with fine tilth and plenty of well-rotted organic matter incorporated. This is recommended for anyone who is fit and has a heavy soil. Using traditional methods, the potato plot should be cleared and dug over in autumn or winter with loads of manure incorporated. Frost breaks the soil structure down so that tubers can be simply and quickly dibbled in during spring, usually on Good Friday. Alternatively, trenches can be dug at spade depth during spring and the bottom should be filled with organic matter or fertiliser. Some soil is then added before the tubers are placed and then covered. Loosening the soil on either side of the trench with a fork leaves it ready for earthing-up when the plants emerge and grow.
Simply placing the tubers on the ground surface with compost and covering with a thick layer of mulch, such as straw, will give results. The drawback is that it allows easier access to the crops for slugs and mice. Alternatively, loosen the soil with a fork, dig small holes with a trowel for the tubers and place the compost manure or fertilizer on top of the rows. Use wider spacing than the traditional distances given below. Earth up as the plants grow using the extra earth between the wider rows.
When the potatoes have emerged a few inches, earth up the drills with a rake or hoe. This gives the plant a volume of soil to grow in, it improves drainage and improves ventilation around the base of the plant. Above all, it is a quick and effective way of controlling weeds. Repeat the process as required until the foliage is too big to allow you to continue.
Chitting - encouraging the seed potatoes to sprout before planting
This process allows strong, green chits (sprouts) to develop on the tuber before planting. Dormant or just sprouted seed potatoes can be set up in trays with the sprout end (rose end) facing upwards. Place in a frost-free, light area e.g. the windowsill of an unheated room, as the warmer the room the faster the process. It is generally agreed that chitting is recommended for First Early varieties as it gives the tubers a faster start and the crops will reach a useable size slightly earlier.
If apical dominance is encouraged during chitting, by removing all side shoots and just leaving the rose end sprouts, the growing plant will produce fewer, but larger tubers (ideal for producing a crop of baking potatoes). If all sprouting shoots are left on the tuber, the growing plant will produce more numerous, but smaller tubers (ideal for First Earlies and Salads).
The full situation is, however, more complex and the technical description – “premature ageing” – gives an indication of this. Chitting does speed things up in the beginning, but it also speeds up the onset of senescence (the natural dying-off of foliage), therefore potential yields can be reduced. This is not a problem with First Earlies, as these crops are lifted as soon as they are ready. This also applies to some Second Early and Salad varieties. Chitting Maincrop varieties is not really essential, although if sprouting has started anyway, this process will keep them in best condition as it is possible to manipulate tuber numbers against size.
Spacing, depth and row width
Traditional planting distances are:
First Earlies Plant 30cms (12ins) between tubers At 10cms (4ins) deep.
In rows which are 45cm (18in) apart.
Second Earlies Plant as per First Earlies.
Salads Plant as per First Earlies.
Early Maincrop Plant 37.5cms (15ins) between tubers. 10cms (4ins) deep.
Plant in rows which are 67.5cm (27in) apart.
Late Maincrop - Plant as per Early Maincrop.
Second Earlies can be given more room and Early Maincrops less room, depending on the area available. If plants are too close, tuber size will be reduced. If plants are too far apart, tubers grow very big, space is wasted and weeds grow more readily. The best potato plots are those where mature plants touch without being stressed, but at the same time weeds are suppressed.
Planting in containers
Potato barrels and larger pots can be used to plant seed potatoes. However some times compost can become very compressed due to watering or wet weather, and the plants do not grow properly. This can be remedied by incorporating some form of perlite or organic matter, which will stop the compost compressing but will not harm the growing tubers. The smaller the container, the smaller the area the potato plants have to grow. Therefore try to use containers with a diameter of at least 20cms (8ins) to allow plants to develop properly. Make sure that there is adequate drainage in the container and then place around 10cms (4ins) of compost mixed with perlite into the pot., add the tuber and then cover with around 5cm (2in) of compost. As the potato leaves begins to show through the compost, add more compost and continue this process at intervals until the container will not hold any more compost. Then allow the plant to grow normally and when the pot is ready to harvest (see our Harvest Guide) you should find that your container is full of potatoes.
Best varieties for containers
First Earlies and Salads are best grown in containers, as these can be started indoors or in a frost-free area and then placed outside when the risk of frost has passed. This will mean that you will have very early crops of tubers and can savour the taste of home grown new potatoes early in the season.
Harvest time depends on:
• Planting date.
• Weather and temperature at planting time.
• Weather during growing season.
• Variety maturity.
• Weather and temperature at harvest time.
Generally, seed potatoes will be ready to harvest as follows:
HARVEST PERIOD: June to July. Best harvested in small quantities and eaten when fresh when first flowers appear
and edible tubers underneath.
HARVEST PERIOD: July to August. Best harvested in small
quantities and eaten when fresh. Allow to grow
bigger than First Earlies.
HARVEST PERIOD: July to August. Best harvested in small quantities
and eaten when fresh.
HARVEST PERIOD: August to September. Allow the foliage to
die back before harvesting.
HARVEST PERIOD: September onwards. Allow the foliage to
die back before harvesting.
When to eat...
First Earlies are best eaten fresh, at the start of the season.
Second Earlies and Salads can be eaten fresh or stored, provided the skins are “set” and do not rub off when harvested. For storage, harvest in September, having cut down the foliage to stop continued growth, and treat as per Maincrops, below.
Maincrops can be stored, as long as the tubers are lifted in dry conditions or dried properly. Put into a hessian sack and store in a cool, dark, frost-free area.
Pests and Diseases.
Thanks to WCF-Phoenix for this guide.
Certified Seed Potatoes
Saving money by not buying certified seed potatoes is, in most cases, short sighted. Low grades, table potatoes and garden grown seed potatoes carry more spores of bacteria and fungal pests than high grade certified seed potatoes. In addition, non-certified seed can carry PCN eelworm, or can be treated with sprout suppressant.
Blight occurs in mild, moist conditions. The initial signs are the development of small dark areas on the leaves. White threads appear on the underside. The stems may also develop dark brown patches at areas where leaves join them. Infected tubers have brownish discolouration and the flesh has a marbled appearance before rotting away.
PCN (Potato Cyst Nematodes)
Plants will appear stunted and weak with the foliage having a dull wilting appearance. Cysts of approx. 0.05mm in diameter will appear on the roots and tubers. There are two species of PCN which occur during mid-July and mid-August. The species are best deciphered by their colour, Golden Yellow cysts = Globodera rostochiensis, Creamy White cysts = Globodera pallida. These cysts in both strains will turn a reddish brown colour at maturity.
This is a common bacterial soft rot. When this occurs the stem of the potato is infected, it will turn black and decompose, followed quickly by the potatoes. The plant leaves turn yellow and the plant slumps.
Common Scab is caused by a fungus. Cases are worst in dry conditions. However watering at the time tubers are developing will decrease the level of infection in tubers. Levels are also lower in slightly acid soils. Scab is superficial – it does not affect yield but it is unattractive.
A common problem in potatoes. Showing as odd shaped holes on the surface leading into large holes in the actual tuber. More common in potatoes planted in heavy wet soil. A late harvest may mean tubers are more at risk as slugs are more active around the late autumn period.