August 13, 2019
Nurtured in Norfolk’s gardening expert Martyn Davey answers all your questions.
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Potatoes are hugely versatile and a staple ingredient of many meals in one form or another. Potatoes are classified as being either earlies or maincrops. Early varieties are ready to harvest much sooner than maincrops and are what we call ‘new potatoes’. Maincrop varieties are in the ground a lot longer. They have a better yield and produce larger potatoes.
Potatoes are grown from special ‘seed’ potatoes called tubers. These are certified virus-free. Buy seed potatoes from late winter onwards. It’s important with earlies and a good idea with maincrops to ‘chit’ the seed potatoes first before planting; this means allowing them to start sprouting shoots indoors. Stand them rose end up (the rose end is the one with the most small dents in the skin, or ‘eyes’) in egg boxes or similar in a light, frost-free place. The potatoes are ready to plant when the shoots are about 3cm long. On early potatoes, rub off the weakest shoots, leaving four per tuber.
Follow these guidelines for planting times of seed tubers: First earlies: around late March, Second earlies: early to mid-April, Maincrops: mid- to late April. If you are planting in containers, start even earlier. Potatoes need a sunny site away from frost pockets – the newly emerging foliage is susceptible to frost damage in April and May. Prepare the ground the previous autumn or winter by digging in organic matter such as well-rotted animal manure.
The traditional planting method is to dig a narrow trench 12cm deep. The seed tubers are spaced 30cm apart for earlies and 37cm for maincrop varieties in rows 60cm apart for earlies and 75cm apart for maincrop. Apply a general purpose grow more fertiliser at this stage.
When growth emerges, start the process of ‘earthing up’. Wait until the stems are about 23cm high and draw soil up to the stems creating a ridge about 15cm high. As the stems grow, repeat the process. The final height of the ridges will be about 20-30cm. Earthing up protects newly emerging foliage from frost damage. It also protects the developing potatoes from light that turns potato tubers green. Green potatoes are poisonous.
Keep crops well-watered in dry weather; the vital time is once the tubers start to form. Maincrop potatoes benefit from a nitrogenous fertiliser around the time of the second earthing up.
First early potatoes should be ready to harvest in June and July, second earlies in July and August, maincrops from late August through to October.
These are the best varieties to grow: ‘Picasso’ AGM: A heavy-cropping maincrop potato with creamy skin and pink eyes. It has good disease resistance to scab. ‘Accent’ AGM: A first early with creamy waxy flesh and good scab resistance. It’s a very tasty new potato. ‘Desiree’: A firm favourite with rosy skin and pale yellow flesh. This is a versatile maincrop potato. ‘Charlotte’ AGM: This is a salad potato, with yellow-skinned waxy tubers. Treat as an early potato.
Jobs for this week in the garden.
Protect new spring shoots from slugs and snails, only use bird friendly pellets or other organic methods.
Plant shallots and onion sets these are hardy and will stand the odd light frost.
Plant summer-flowering bulbs, I know it sounds early but now is the time for summer bulbs.
Martyn Davey – Head Grower