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Root crops

Prof Walker shows us how to go about planting root crops.

Root cropsWelcome to my garden. I want to talk about root crops today — carrots, parsnips, beetroot, kumara and yams.

They've got one thing in common: they like a deep, well-drained, beautifully structured soil.


The kumara's been an important crop in NZ ever since people have been here. It is subtropical so it does best in the north where it's warmer. But I can grow it down here in Christchurch on my slope.

Kumara shootsIf I want to grow kumara, I get a disease-free tuber then I plant it in moist sand or moist compost. I'll keep that moist and warm in my glasshouse for about six or eight weeks, in which time it develops these shoots. You may get as many as 30 of them from one plant.

I then plant them into compost for two to three weeks till they develop a much better root system and have a much better chance of catching on and growing and giving us a good crop.

Carrots, Parsnips, Beetroot

Carrots, parsnips and beetroot are all sown as seed. I prepare the seedbed in very much the same way. I'll show you today how I'd sow my beetroot.

BeetrootFor all these crops I sprinkle fertiliser like Nitrophoska Blue at the rate of a handful to a metre. Lighter for carrots because we don't want too big a top for those. Beetroot and parsnips, I'm a little heavier.

Then I hoe it in thoroughly. Beetroot seed are quite big. They don't need to be pelleted. Sometimes you get big seeds containing clusters of three or four.

I like to sow them 2 cm, 3 cm, 4 cm apart. Of course, they'll still need a bit of thinning later on.

Sowing seedsIt remains for me to cover up the seed and also to use the back of the rake to compress it to keep the moisture moving up.

Carrots can be sown almost any time in the warmer areas, but in much of the South Island they're mainly grown from early spring to January.

At this time of the year I've already harvested my parsnips as they keep well in the freezer. But in the case of the carrots and beetroot here, I've taken off the tops already once, and they're beginning to grow away again. And this is to delay them going to seed and becoming fibrous.


YamsYams are another root crop that my family loves, especially roasted round the joint. I shouldn't call them yams. Our scientists want us to call them oca. They belong to the oxalis family and are not a true yam. The true yam is a potato-like tuber.

If you want to grow good yams, buy some good tubers from the supermarket and plant them just like potatoes — 50 cm apart in the row. The more compost they get, the better, particularly if your soil isn't sandy. Then you don't get too many of knobbly bits on them.

I've got here three new cultivars that have been bred out at Lincoln. They've introduced material from South America. They're trying to produce bigger ones of different colour, hoping it will appeal here and overseas. Some of these are so sweet, you can eat them raw.

More on kumara, yams and potatoes


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Last updated: March 1, 2021