Growing Sweet Potato, also Kumara

Ipomoea batatas : Convolvulaceae / the morning glory family

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 63°F and 95°F. (Show °C/cm)
  • Space plants: 16 - 24 inches 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 20 cm (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

25 Mar 24, Peter (New Zealand - temperate climate)
Planted 10 kumera slips in October 2023.... Harvested 50% of them 5 in March 2024....massive green foliage but sadly 6small (very small) finger sized harvest kumera is the only result...starting to get cooler but leaves still dark I leave them in till the weather of leaves change. ( Auckland grower)
07 Apr 24, Marc (New Zealand - temperate climate)
leave Kumara in the ground at least until mid April. Leaves start to die off or in Auckland slow down in growth. Make sure the edges of the bed are well mulched, this will keep the moisture in the ground and the top soil cool (cooler). I harvest the orange (Beaumont) ones first, followed by the red, then purple and gold as last. there is about a week between harvests. Allow the kumara to dry before storage other wise they will rot. Keep them well protected from rats, my first red kumara harvest was approx 20kg until the rats consumed them in 4 nights to 2 kg.
29 Mar 24, Celeste Archer (Canada - Zone 7b Mild Temperate climate)
Harvest once about HALF of the leaves start to fall over and die off (turn yellow) -- HOWEVER I'm not sure if you planted at the being of October or the end. Given good growing conditions it should take about 120 days -- if you planted at the end October then that is about 120 days.... but it could take longer -- and since the leaves have not fallen over, then I would say, it will take more time. If you planted at the beginning of October, then you are taking a lot of days -- and it could be that the growing conditions have not been optimal for the whole time.... and I would still wait for leaves to fall over... but I would start to wonder if perhaps for some reason all the conditions that your plant needs to have met in order to set tubers have not been met (nutrition, soil type/ph, water, sun light, temperatures etc.). Same rule for potatoes, harvest once the leaves started falling over and turning yellow. That is to say: as long as the leaves are a upright and green they are still collecting light and storing energy (making tubers - and making them larger)
24 Feb 24, Gerry (New Zealand - temperate climate)
Hello can I grow sweet potatoes in Clyde Central Otago?
18 Mar 24, Lex (New Zealand - temperate climate)
We have grown them successfully in Balclutha 2021/22 2022/23. This years crop 2023/24 Was slow getting going but perked up in December. The tops havn't grown as much as the previous 2 years but we are hopeful of getting a worth while crop when we dig them up. I would say just have a go. Because we have a shorter season it is tempting to put them in early like 1/11 but we think it is better to wait until the ground has warmed up. cheers Lex
14 Jan 23, Anonymous (New Zealand - temperate climate)
Has anyone planted Kumara in a Vegepod?
23 Jan 23, Anonymous (Australia - sub-tropical climate)
Why would you - they need a lot of soil around them.
14 Mar 22, Malcolm (New Zealand - sub-tropical climate)
I have grown a large bed of kumara in a school garden. The entire bed is covered in healthy top growth. But I can't feel any tubers when I lift up a section of top growth. I'm interested in the comments on pulling up runners, although I may be too late now, in mid-March. Do I just hack away at the long vines, cutting them back to where they enter the soil. Or am I wasting my time, since we are about a month from harvest?
09 Apr 22, Will (New Zealand - cool/mountain climate)
No, you are not wasting your time growing them. Even if there are no tubers, the top leaves can be harvested. They are commonly harvested & eaten in the Philippines. Steam them. They commonly used them with raw tomatoes, in their summer.
15 Mar 22, Mike Logan (Australia - sub-tropical climate)
In sub tropical Australia where I live, they grow them in rows. The rows are hilled up about 1/2m high and the slips are planted in the top of the hill. A slip is the last 200-300mm of the vine when they are about 10 weeks old. Plant the slip with the top part out of the ground, Keep soil moist until they start to grow. Your problem is you probably have over fertilised with nitrogen. Go by the time to harvest guide here if you don't have a crop by say 4mths then you probably won't. The potatoes will be around where you planted the tube or runner not along the vines.
Showing 1 - 10 of 60 comments

Ask a question or post a comment or advice about Sweet Potato

Please provide your email address if you are hoping for a reply

All comments are reviewed before displaying on the site, so your posting will not appear immediately

Gardenate App

Put GardenGrow in your pocket. Get our app for iPhone, iPad or Android to add your own plants and record your plantings and harvests

Planting Reminders

Join 60,000+ gardeners who already use GardenGrow and subscribe to the free GardenGrow planting reminders email newsletter.

Home | Vegetables and herbs to plant | Climate zones | About GardenGrow | Contact us | Privacy Policy

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.
We cannot help if you are overrun by giant slugs.