Plant Doctor Archive

Growing kumara, yams and potatoes

Question CAN someone explain how you plant kumara? Is it from shoots or the whole kumara? Also, the same question about yams. I’m in New Plymouth. What type of potato grows for earliest harvest and when should I put them in the ground?

Answer KUMARA can be grown from either the shoots or the whole kumara, but the usual way is from the shoots, which can be bought from a garden centre. It is really easy (and much cheaper) to grow your own though. This involves selecting one or more disease-free kumara (just make sure it has no blemishes or obvious damage). Take the kumara and place it on, or partially in, damp sand and put it in a warm place. Over a period of a few weeks (perhaps 4–6 weeks), the kumara will put up a number of shoots, which will develop roots in the sand. When the shoots are about 20 cm high and have vigorous roots, you can remove them and plant them out. Kumara are very susceptible to frost, so wait until the chance of frost has gone (usually October-November) and plant them out on ridges of soil (about 20 cm high). They will grow best in light, rich, well-drained soil, in a warm, sunny spot. Good luck!

Yams are planted as the tubers you buy from the grocer, and are grown in a very similar way to potatoes. They like quite a lot of fertiliser and compost. Harvest when the tops die down (around May).

There are a number of early potato varieties you could plant in New Plymouth. Probably the most common is ‘Ilam Hardy’, but there are other, older varieties which are worth a go, including ‘Epicure’, ‘Arran Banner’, ‘Jersey Bennes’ and ‘Cliff’s Kidney’, if you can find them. I suggest planting between July and September for an early (Christmas) crop, but beware of the tubers rotting or getting blight in the wetter conditions (well-drained soil would be a good idea).