How to grow potatoes

A staple in the diet of much of the world and grown on the majority of allotments in the UK, the potato is the most versatile of vegetables. Potatoes can be eaten boiled, mashed, fried, roasted or baked and are used in many dishes. There are whole books dedicated to potato recipes.

Potatoes are classified as first earlies, second earlies and main crop based on the time it takes for them to reach harvest. There are also a vast array of varieties available which give potatoes of different flavours, textures and colours as well as disease resistance.

They are grown from tubers known as seed potatoes rather than from actual seeds. Seed potatoes are grown under controlled conditions and are guaranteed to be free of disease. Using supermarket bought potatoes or leftovers from last year’s harvest is not recommended.

Potatoes like an open, sunny location and benefit from the addition of organic matter such as garden compost or well-rotted manure. They need plenty of water but do not like to be water-logged so you will need to water them in dry periods but be careful not to over-water, especially on clay soils.

Chitting potatoes

Three or four weeks before you intend to plant your seed potatoes you can chit them. This will give them a bit of a head start once planted. If you forget to do this, don’t worry, they will still grow but will take a little longer to be ready to harvest.

Place your seed potatoes in a cool, dry, light place with the end with most eyes pointing upwards. The eyes are the little indentations that the shoots will sprout from. Egg boxes are ideal for this but a seed tray or shallow cardboard box will suffice. Your seed potatoes will grow some short, sturdy shoots and are then ready to plant.

Plant seed potatoes

Seed potatoes can be planted from late March until May dependant on where in the country you are of course.

Planting can be done successionally, beginning with first earlies and finishing with main crop but I usually plant mine all together. Depending on the variety and conditions first earlies take about ninety days to mature, second earlies 120 days and main crop around 140 days or more, so when planted at the same time they can be harvested in succession.

There are several ways to plant seed potatoes. The simplest way is to make a hole 15cm deep with a dibber or trowel, drop a seed potato in with the chits pointing upward and cover with soil. This works well for me and is the method I usually use.

Potatoes can also be planted in trenches. Dig a trench six inches deep by the width of your spade. Place your seed potatoes at the bottom of the trench and draw the soil back over them. Alternatively, make the trench nine inches deep and cover with six inches of soil. Gradually top up with the rest of the soil as the potato’s foliage grows through. This makes earthing up easier later on. You can add a general purpose fertiliser to the soil at this point if you wish.

Space first earlies 30cm apart and allow a minimum of 60cm between rows. Second earlies and main crop potatoes should be 45cm apart and at least 75cm between rows. I allow a metre between rows as this makes earthing up easier, I recommend this if space permits.

Potatoes can also be grown in very big pots or bags but crops are likely to be quite small.

Earth up potatoes

Earthing up is the technique of drawing soil over the potatoes as they grow. There are two reasons we do this. Early in the season it protects the new growth from frost damage. Later it covers the growing tubers as they are likely to push their way out of the soil. Potatoes that are exposed to light will turn green and become unpleasant to eat and are mildly poisonous.

As your potatoes grow, carefully draw the soil from between the rows over the leaves using a rake or hoe. Once risk of frost has passed continue to earth up to keep the tubers covered but not the leaves.

Harvest potatoes

First early and second early potatoes should be ready to harvest when flowers appear. Have a careful dig around the plant with your fingers or a trowel to see if they’re big enough to cook. Although some varieties will store for a while most taste best fresh from the ground.

Main crop potatoes are ready to crop when the foliage begins to die. Once this happens, cut it off and leave the potatoes in the ground for a few days to allow the skins ripen. This helps them stay in good condition. I recommend harvesting them all once they are ready. The longer they stay in the ground the more likely they are to suffer from slug damage and eel worm or wire worm attack.

Believe it or not you can buy a special fork for harvesting potatoes but I’m not sure what their purpose is! Just start digging a good distance from the plant and work your way towards it. If you stick your fork into a potato it will have a hole in it whatever type of fork you use! Clean any damaged potatoes and use them straight away, don’t store them long term as they will soon begin to rot and may affect other tubers.

Storing potatoes

Most varieties of first earlies and second earlies are best eaten fresh from the ground but will store for several days in a cool dark place.

Main crop potatoes should be allowed to dry once harvested. any excess soil should be rubbed off by hand. They can then be stored in paper or hessian sacks or cardboard boxes in a cool, dry, dark place for several months.

Do not store potatoes in plastic containers.

Potato problems

Potato blight is the worst problem for potatoes. The leaves of affected plants darken at the edges, have mould on them and soon begin to die completely. Once blight strikes it will quickly affect the whole crop. Unfortunately it is quite common in the UK and there is no effective remedy available to gardeners. It is a fungal disease that strikes during warm, humid periods. If your crop is affected cut off the leaves and harvest what crops you have. This should stop the disease reaching the tubers which will also rot if affected.

As it sounds, Potato scab causes scab-like damage to the potato’s skin. It has no affect on the rest of the plant so you will not be aware of it until harvest. Whilst it does not look pleasant it is harmless and the potatoes remain edible. Once peeled you won’t know it was there. Affected tubers may not store well and will be more inclined to rot.

Eel worm, wire worm and cut worm are not actually worms but the larvae of various insects. They all bore into the tubers causing unsightly, unappetising holes which make the potatoes more likely to rot. Build up of these pests can be reduced by avoiding planting in the same place repeatedly.

Potatoes are also susceptible to Slugs.