Root vegetables
Potato
Solanum tuberosum
Timings for your region
Suggested: Moderate · Explained in the glossary
Never sown — tubers go straight into the bed.
Plantingearly April – early May
Harvestlate June – early October
Practical tip
Earth them up once the foliage is 20 cm tall — tubers that reach daylight turn green and are no longer edible.
Origin & history
The potato comes from the Andes, where it has been grown for thousands of years, and reached Europe in the mid-16th century as a botanical curiosity — it took far longer to be eaten. In Prussia Frederick II pushed it into the fields from 1756 with his so-called potato orders. Almost all European varieties go back to a very narrow selection of early introductions, which is why late blight hit the continent so hard in the 1840s.
Varieties
Seed potatoes are chosen on two axes: the maturity group, from very early to late, and the cooking type — waxy sorts like “Linda” or “Sieglinde” for salad and frying, floury ones like “Adretta” for mash and dumplings. Take certified seed potatoes rather than supermarket ware: that is often treated to suppress sprouting and can bring viruses with it. Early varieties have the advantage in wet summers because they are lifted before blight really gets going; there are also varieties bred to tolerate it, such as “Bionica” or “Toluca”.
Care
Four to six weeks before planting, chit the tubers somewhere bright and cool at 10 to 15 °C — short green sprouts, not long white threads; that buys two to three weeks. Late frosts in May blacken the young foliage, so lay fleece over them or draw soil across the shoots when frost is forecast. The decisive phase for yield is flowering: if it stays dry then, the plant sets only a few small tubers. Go easy on nitrogen, or you get a lot of foliage and little underneath.
What can go wrong
Colorado beetles and their red larvae are picked off by hand — the orange egg clusters sit on the undersides of the leaves, and wiping them off twice a week keeps the infestation in check. Late blight shows as brown leaf patches with a pale margin after wet weeks; once the foliage has gone, cut it off close to the ground and wait two to three weeks before lifting so the spores die off and the skins set. Scab — rough, corky patches on the skin — comes from dry, freshly limed soil and is purely cosmetic. Do not bring potatoes, tomatoes or aubergines back to the same bed for three to four years.
Harvest, storage & kitchen
Early potatoes are lifted from flowering onwards; if the skin rubs off under your thumb they are not yet storable and should be eaten soon. Main-crop potatoes are only lifted once the foliage has died down, left to dry on the bed for a few hours and stored unwashed — the soil clinging to them protects better than any washing. Keep them dark and airy at 4 to 8 °C, but not in the fridge: there starch turns to sugar, the potatoes taste sweetish and fry dark. Apples do not belong in the same room; the ripening gas they give off makes the tubers sprout earlier.
All timings are guide values for the given climate, not a guarantee. Weather, aspect and variety all have a say.