Start off some new potatoes in sacks undercover now and you could be harvesting your early summer treats weeks earlier this year! Forcing new potatoes is a great way to sneak in an early harvest long before any spuds would be ready to eat outdoors. It fools tubers into thinking it’s spring – so they burst into growth weeks earlier than usual.
We’ve got seed potatoes in stock right now at the garden centre here in Poynings so hurry over now to get the varieties you want before they sell out. You need a first early variety: the fastest to produce a crop are ‘Swift’ and ‘Rocket’ but any first early will do well. If you don’t mind waiting a little longer, ‘International Kidney’ – the gardener’s version of the famous Jersey Royal – has particularly good flavour.
Potato sacks are designed for the job and will keep your tubers happy right up till you’re ready to harvest. Place a layer of compost in the bottom, about 30cm deep: for best results, use a 1:3 mix of soil-based John Innes no.3 and multipurpose compost, and mix in a handful or two of specially formulated potato fertiliser.
Place three tubers on the top. Cover with another 30cm of compost. Water them in well, and place in a cool greenhouse, conservatory or bright, sunny porch: they need to stay fairly warm, with plenty of light.
Keep them well watered and within a few weeks, you should see shoots emerge. Add more compost to cover the stems, right up to the topmost tuft of leaves. Keep doing this as the plants grow until you have completely filled the bag. Then let the plants grow on. In early May start to feel gently into the compost; as soon as you come across tubers the size of hen’s eggs, your crop is ready to harvest.