Potatoes

Choose a sunny spot, but don’t plant potatoes in the same place each year or where tomatoes have been planted the previous year, as diseases like blight can linger in the soil. Potatoes hate frost so plant after all risk of frost has passed, or protect the emerging growth by mulching.

Potatoes are gross feeders – you’ll often find a really strong potato plant self-seeded in the compost heap. They love rich soil, but don’t give them too much nitrogen or all their energy goes into the leaves, not into making potatoes. Use a specialised potato fertiliser containing specific proportions of nitrogen, phosphorus and potash (potassium) to boost tuber growth. Dig a trench and then dig in a layer of vegetable mix and a handful of potato food.

Start with certified seed potatoes, they are guaranteed to be disease free. At least a month before you plant them, put them in a tray in a dry airy place in the shade, until the spouts are 2-4 cm long. This is called chitting. Avoid direct sunlight or they will go green. Plant them in the trench about 25cm apart, then cover with soil to a depth of about 5cm. When watering, water the soil only, avoiding the foliage, as this will discourage blight.

As shoots grow, mound up the soil to cover them so the shoots are just poking through. This mounding gives protection against wind and frost, helps encourage tuber development rather than leaf growth (the potato will keep producing new potatoes up the stem that is covered) and also prevents greening – green potatoes are toxic. Keep mounding until the plants are about 30cm tall, then let the foliage grow up and flower.

Main variety potatoes are ready to harvest after their flowers die back (usually 3-4 months after planting). Not all varieties flower – some early varieties don’t have flowers or are ready to harvest once they flower. They produce a fruit on the top, which is poisonous.

Quick-growing potato varieties have soft skins you can rub off – these early potatoes won’t keep so enjoy them straight away. Main crop varieties take longer to grow and have hardened skins.

Dig them up and leave them to dry then store in sacks in the dark in a well-ventilated spot. You can leave main crop varieties in the ground until early winter, but dig them up before the ground freezes or gets too wet or they will rot.

Potato varieties