GARDEN ADVICE

How to Grow Potatoes and Onions

Potatoes are such a versatile vegetable. January and February are the months to decide which varieties. This is so much a question of personal taste that it is difficult to make recommendations. Therefore look for a variety that you enjoy eating and that crops when you want it to.

Traditionally, potatoes are categorised according to when they crop; First Earlies, Second Earlies and main crop. First Earlies can be harvested in June and July, Second Earlies in July and August and main crop in September to October.

Seed potatoes are available from garden centres for a few weeks early each year. The reason why it is important to buy seed potatoes rather than using some that have started sprouting in the vegetable rack is that they are certified virus-free. Having chosen your variety, potatoes should be 'chitted'. This is done by placing them in a box in a light, dry airy place. This allows shoots to form so the tubers get off to a quicker start when planted in the garden. Start chitting as soon as the days start to lengthen. Chitting usually takes about a month but this depends upon variety.

If you have not already done so, dig over the potato patch and incorporate compost or well-rotted manure into the soil. In spring fork over the area and add a fertilizer such as Growmore.

Some people plant potatoes in trenches, others in planting holes. In any event potatoes should be planted about 6 inches in depth and each tuber 6 to 12 inches apart. Cover with soil and heap the soil up around to create a mound.

As soon as all the leaves have appeared, start earthing up the potatoes by covering all but the top of the leaves. With first earlies this may have to be done more than once. The reason for earthing up potatoes is to protect the plant from frost damage, prevent light from getting at the potatoes and turning them green, and it also helps to protect against potato blight.

Potato blight is an airborne fungus which spreads in warm damp weather. It doesn't usually affect early potatoes but if you notice yellow/brown marks on the leaves, cut off the top growth and burn it. The potatoes left in the ground should still be okay for a couple of weeks but will not grow any further. Other problems can include slug damage, wire worm and scab. Watering helps to increase the yield and to prevent scab. Crop rotation will also help keep these problems at bay.

If potatoes are as easy to grow as they are delicious then why not try propagating some onions as well. Onions can be grown from seed or as sets which are basically immature onions which take about 5 or 6 months to grow to maturity. Seed takes a little longer. Plant sets as soon as the ground is warmed up a little in March or April. Plant them so that two thirds of the bulb is buried beneath the surface. Onions need plenty of water and do not like competition from weeds. They do best in rich soil that has been well manured. Harvest just before the onions set seed.