When & how deep

Earthing up ... I'm no expert either, but I have read stuff about it over the years. My take is...

- There are two kinds of earthing up: for frost protection and for increasing crop.

- Early in the season, pulling loose soil over tender young growth protects them from frost. But for us home gardeners it would be just as easy to use fleece.

- Later on once there's no more risk of frost, pulling soil up around the stems creates ridges. The ridges catch more sun than flat ground, making the roots warmer and encouraging better growth. Potatoes do after all come from further south than the UK where the summer sun is quite a bit stronger. They like it warm! It also helps cover up any tubers that are forming near the surface, so it's worth doing for that reason alone. You don't want to be covering up any leaves here, they are making food for the plant.

- I've heard people say that the potato plants will make extra roots from the stem, like tomatoes do. Whether they do or not, I'm not convinced this makes any difference to the crop.

Anyway, I usually earth up my potatoes, if I remember.