Seed tubers should be planted around late March for first earlies, early to mid-April for second earlies and mid- to late April for maincrops. This varies slightly depending on where you are in the country.
There are numerous ways of growing potatoes.
It's vital with earlies and a good idea with maincrops to chit the seed tubers first before planting; this means allowing them to produce sturdy shoots. Buy your seed potatoes in late January/February and stand them rose end up (the rose end has the most eyes) in egg boxes or similar in a light, frost-free place. The tubers are ready to plant when the shoots are about 2.5cm (1in) long.
The traditional way is to dig a narrow trench 12.5cm (5in) deep. This can be lined with compost or even grass clippings for a better crop. The seed tubers are spaced 30cm (12in) apart for earlies and 37.5cm (15in) for maincrop varieties in rows 24in (60cm) apart for earlies and 75cm (30in) apart for maincrop. Sprinkle slug pellets or other slug deterrents between the tubers as keel slugs can be a problem.
When the stems are about 23cm (9in) high start earthing up by carefully drawing soil up to the stems and covering to produce a flat-topped ridge about 15cm (6in) high. This can be done little and often or in one go.
The other method is to grow the potatoes under black polythene. The tubers are planted through the black polythene. The advantage of this method is that there is no need to earth up and the new potatoes form just below soil level which means there's no digging to harvest them.
It's also possible to grow them in large containers - or even black bin liners. Line the bottom 15cm (6in) of the container with potting compost and plant the seed tuber just below this. As the new stems start growing, keep adding compost until the container is full.
Keep crops well watered in dry weather; the vital time is once the tubers start to form. A liquid feed of a balanced general fertiliser every fortnight can help increase yields.
First earlies should be ready to lift in June and July, second earlies in July and August, maincrops from late August through October.
With earlies wait until the flowers open or the buds drop; the tubers are ready to harvest when they are the size of hens' eggs. With maincrops for storage wait until the foliage turns yellow, then cut it and remove it. Leave for 10 days before harvesting the tubers, leaving them to dry for a few hours before storing.
