Kumara Ipomoea batatas. Sweet potato

Like potatoes, kumara are a ‘dime a dozen’ when in season so I only grow them for the fun of trying as our garden isn’t huge. However, if you have a taste and the space for them then they are well worth including in your spring planting schedule. Like potatoes, kumara can be grown as a ground cover plant and soil conditioner with their dense foliage suppressing weeds and the action of their roots improving soil structure.

Companions Sunflower, cosmos.

Quantity 2 plants per person

THE GROWING LIFECYCLE



Kumaras

  • Warm sunny spot
  • Shallow rich soil
  • Plant tubers or cuttings
  • Can grow in pots
  • Fun for kids


Our Top 2 Varieties

Purple kumara probably the most popular here in NZ . Hard-fleshed when raw. Texture is crumbly –like a potato when cooked.

Golden kumara orange varieties have softer flesh that is moister and sweeter tasting than purple varieties.

Getting started

When

In warmer areas kumara can be planted from August to December.  
In cooler areas you should wait until general risk of frosts has passed before planting – usually sometime around late October and running through to late December.

Where

A warm and sheltered sunny part of your garden.

Soil

Kumara are grown in free draining, rich organic material above a hard soil base which stops their roots running and running and tells them its time to develop the edible tubers. This is one vegetable where deep and thorough digging is therefore to be discouraged. The best way to grow kumara in an open garden is to mound up soil, sand, rotted manure and compost into a shallow hill that is as wide and as long as the area you want to plant in. This hill should be about one and a half hands deep. As well as rotted manure and compost you can add wood ash and seaweed for extra potassium.

Kumara can also be grown in anything from a stack of old tyres or a half wine barrel  to a plastic bin bag (see end of text).

SOW & PLANT

PLANT

Kumara are planted as green shoots – or cuttings - and as sprouted tubers (basically kumara as we know them with shoots coming out of them).
Cuttings can be purchased from garden centres, nurseries and some health food stores in spring.
You can sprout your own tubers by burying them just below the surface in boxes of moist sand placed in a warm sunny position – indoors if neccessary. When these boxed kumara have developed shoots about half a thumb’s length they can be planted. You could try growing your own ‘cuttings’ by letting the shoots on your boxed tubers reach a full hand’s length and then carefully cutting them from the face of the tuber.
Nestle your sprouted tubers or cuttings about an arm’s length apart on your hill of prepared soil. Tubers should be buried about a finger deep and cuttings should be planted with their bottom half in the soil – bend the lower half as you put into the soil so that it sits like a ‘U’ under ground. Cuttings and tubers need good access to moisture for the first week or two, so if its dry water accordingly. Thereafter they should be able to fare for themselves.

MAINTAIN

When shoots start to form runners and cover ground they should be periodically lifted to stop them from taking root on the surface.

Containers: If you are planting in containers this can make it easier to utilize the sunnier parts of your garden and to contain the sprawl of these plants in smaller gardens.
Planting into car tyres, half wine barrels or plastic bin liners is relatively easy and can be fun for kids:

Mix up soil, sand and rotted manure, compost and seaweed in a wheelbarrow.

Position your half barrel and ensure it has several drainage holes in the bottom. If using tyres, place two or three on top of each other. If using a large bin bag, open one up and place on the ground. Make about 10 or 12 small holes for drainage in the bottom of the bag.

Fill your chosen planting container with prepared planting mix.

Plant 2 to 3 sprouted tubers per bag, barrel or tyre stack. Tubers should be buried about a finger deep.

Water as needed in first two weeks and then sparingly thereafter – only when it is dry.

HARVEST OR PICK

Kumara need between 4 and 5 months to mature. Wait until foliage has all turned yellow before digging carefully. I do this by hand in containers. Kumara, once lifted, are left on the soil’s surface to cure (develop are dry, firm skin) for a few days. Store undamaged tubers in sacks in a cool dry, frost-free place.