Expert garden advice from the RHS: does it matter if I cannot cover my potatoes with soil?

The experts at the RHS answer your gardening questions...
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Question: I am growing potatoes for the first time in a raised bed. The leaves are now several inches high but it will be difficult for me to cover them with soil in what is a restricted space. Does it matter? I'm sure I read recently that it won't affect the potatoes themselves.

Answer: The reason for 'earthing up' the potatoes - drawing up the soil so that the tops of the foliage just show - is to prevent the tubers turning green in the light. Green potatoes are poisonous. If you cannot add soil, you can peg down black landscape fabric so that it covers the areas where the potatoes will be developing. The best way to do this is at planting time. Peg down the fabric and cut holes for the potatoes to be planted through. If you use this method, it is a good idea to lay leaky hose underneath to ensure your crop receives enough water. A good thick layer of mulch, such as well-rotted garden compost, would be just as good at this stage.

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