As a rule, I discourage small-space gardeners from growing potatoes as they need a fair amount of room and are cheap to buy. Nonetheless, they’re a classic grow-your-own crop: satisfying to cultivate, a pleasure to harvest and delicious – especially if you choose a variety you might not see in a supermarket, such as the heirloom variety Sharpe’s Express (pictured above).
Potatoes are divided into different groups based on how long it takes them to produce crops. The most coveted – and expensive – are the “first earlies”, or new potatoes, which can be planted now and into April, to be ready in June and into July. Those that follow are called “second earlies” and go into the ground a couple of weeks later, to be dug up in August. The earlies are delectable when freshly harvested; they can’t be stored for long and have the added bonus of (hopefully!) hitting your plate before blight threatens.
Maincrop potatoes have the longest growing period, are planted in late spring and produce the largest tubers come late summer/autumn; many varieties will store into winter.
Potatoes are grown from seed potatoes which are cultivated by professionals who select for quality and to ensure they are disease-free. Some gardeners chit their seed potatoes before planting them, which means placing them somewhere frost-free until they sprout. If you remove all but the strongest three or four shoots before planting, you’ll get fewer, larger tubers, whereas leaving more shoots intact will produce more but smaller potatoes.
Potatoes require well draining, fertile soil to grow. I’ve only ever grown potatoes in containers – grow bags, specifically – as my clay soil can get waterlogged in a wet spring which would put the seed potatoes at risk of rotting. Early seed potatoes need to be planted 15cm deep, with 30cm between each tuber. Maincrop potatoes need an additional 10cm of space. A 40-litre fabric grow bag half filled with compost can accommodate three or four early-variety seed potatoes, which will produce a worthwhile harvest.
Potatoes need generous watering and feeding using homemade comfrey feed or liquid seaweed, especially if grown in containers.
After your potatoes emerge above the soil line, they’ll need to be earthed up. This process involves piling up soil or compost over the stems, which will prompt the potatoes to develop along them. Doing this will protect the shoots from late frost – although if there is foliage, add fleece too.
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You can check whether your potatoes are ready to harvest by carefully unearthing one or two to see whether they’ve reached a size you’re happy with. If not, leave them to grow on for a few more weeks, then try again.