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Growing Sweet Potato, also Kumara

Jan F M A M J J A S O N Dec

Not recommended for growing in New Zealand - cool/mountain regions

  • Plant shoots or cuttings (Slips). Best planted at soil temperatures between 17°C and 35°C. (Show °F/in)
  • Space plants: 40 - 60 cm apart
  • Harvest in 15-17 weeks.
  • Compatible with (can grow beside): Best in Separate bed
  • New shoots on Kumara
  • Well grown Kumara

Sweet Potatoes require a long warm growing season. Plant in free draining loose soil . Fertilise before planting but no more when the plants are growing as it will encourage vine growth. They will go for miles and you will get no tubers. If they do start spreading, lift the vines off the ground to prevent them rooting.

Mound up the soil about 20cm (8 in) before planting Let the plants die down, (leaves die or turn yellow) before harvesting the tubers. Dry them in the sun for a few days . then store in a cool dry place for up to five months.

Culinary hints - cooking and eating Sweet Potato

Use mashed, boiled, roasted, baked or fried. Or use in soups, pies, casseroles, curries and salads.

Your comments and tips

24 Oct 19, anon (Australia - sub-tropical climate)
I talked to a commercial grower yesterday. Fertilise the ground before you plant. What fertiliser you use depends on how fertile your soil is. You would need a soil test to really find that out. But fertiliser with a reasonable amount of N, good P and high K. Mix this through the soil profile. If you cut off slips, make them about .4m long, strip off most of the leaves but leave the growing head part. Dig a furrow 50-75mm deep and place the slip in the furrow (place the slip level in the soil). Cover the slip over with soil but leave the growing bit sticking out of the soil. You could put the slips in a jar of water for a week or so to start the roots growing. Once you have planted the slip make sure it is watered for the next week, lIke each day. The soil around the slip has to be wet for the roots to shoot and grow. After a week or so you should notice the plant growing. The slip will produce sweet potatoes from where you stripped the leaves off giving a higher yield of crop. If the vines grow really long then I believe too high N, but I was told they need plenty of N. I was mainly asking about the placement of the slip but will ask more about the fertiliser next time.
26 Jul 19, Laurie Whelan (Australia - sub-tropical climate)
What fertilizer should you use prior to planting?
29 Jul 19, (Australia - sub-tropical climate)
Go on the internet and find out what N P and K do for plants. Then think about what you are growing with sweet potatoes.
04 Oct 19, Rachel Barley (Australia - sub-tropical climate)
They're ON the internet, anonymous.
30 Jun 19, Ev (Australia - tropical climate)
I find that the purple ones grow the best in my garden. Problem is I have miles of plant and not so many tubers. Going to use some of the advice I have read on this page and feed with seaweed.
03 Jul 19, (Australia - arid climate)
Don't fertilise with nitrogen.
27 Jun 19, Ana (New Zealand - temperate climate)
Try this page: They have the most thorough advice on growing kumara that I've seen.
12 Apr 19, June Wark (Australia - temperate climate)
I’ve got orange sweet potato slips growing but your table @page top states not suitable for growing temp. zones - could you tell me why please. Very willing to learn as l’m new to growing veggies. Thank you.
26 Apr 19, Graham smith (Australia - temperate climate)
Hi June. I plant a sweet potatoe around August or September and let it grow wild. Then I take cuttings from that about 3weeks before Christmas and plant them out ,making sure I water them in really well for the first week or so. Then I harvest them just after the first frost with pretty good success.
06 Apr 19, Sam (New Zealand - temperate climate)
Hi there.. I harvested my Kumara in March and unfortunately most of them tubers had multiple small holes in them. Looks like some type of insects got there first and ruined it. Is there anything that I can spray them with and kill them little bugs before they ruin my crops next season.. cheers
Showing 1 - 10 of 220 comments

It may survive if you plant it now - might not grow much or produce a crop. Might be better to try again say Oct and plant out Nov Dec. You are temperate climate.

- Mike Logan

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This planting guide is a general reference intended for home gardeners. We recommend that you take into account your local conditions in making planting decisions. GardenGrow is not a farming or commercial advisory service. For specific advice, please contact your local plant suppliers, gardening groups, or agricultural department. The information on this site is presented in good faith, but we take no responsibility as to the accuracy of the information provided.
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