Growing kumara in containers is a great option if you have limited space in your garden. I had never grown kumara (sweet potato) in my garden before because they spread and use up too much valuable space but when I saw a bunch of kumara slips or shoots for sale in the garden centre, I couldn’t resist giving it a go and thought I’d try growing them in containers.
The kumara shoots came in a big bunch that I couldn’t possibly use all of but I shared them with friends. If you want you can grow your own shoots from a kumara tuber: sprout the tuber by burying it just below the surface in a pot of moist sand placed in a warm sunny position. You can plant the whole tuber once it has sprouts a couple of centimeters long or let the shoots get to 15cm or so and then carefully cut them from the tuber.
I used re-purposed plastic recycling bins as my containers, filled them with some container mix and compost and placed them in a nice sunny spot. Containers are actually great for growing kumara because they need a hard soil base (or in this case the base of the container) which stops their roots running and running and tells them it is time to start developing the edible tubers.
I planted 5 shoots per container. I had heard that the shoots should be planted with their bottom half in the soil with the lower half bent upwards to form a ‘U’ shape under ground. Then keep them well watered so that they can get established.
The plants established nicely and grew lots of healthy looking leaves. After a while they started to spread and long tendrils of runners went out in search of new places to take root – make sure you lift these occasionally to stop them taking over the garden. You need to keep them watered over the summer but not too wet.
Harvesting of kumara usually occurs in late autumn once the leaves have turned yellow. We had such a strange year with a seemingly endless autumn that this didn’t happen until July this year, which is really mid-winter. Even then I wasn’t entirely sure if they were ready and eventually got impatient and decided to dig up one container to see what was going on: to start with I thought they hadn’t formed any tubers at all but they were all at the bottom of the container.
Lift the tubers carefully out by hand and then you are supposed to leave them on the soil surface for a few days to cure and develop a dry firm skin. I didn’t do this because some of mine looked quite black and a bit slimy so I gave them a good scrub and then left them to dry spread out on newspaper. Hopefully they will still store well.
I harvested 3.75kg of kumara from my two recycling bins: one was very large, half a dozen were of reasonable size and the rest were very small. I don’t know whether this was because I planted too many in the container, whether I needed to have used more compost and manure to give them a richer soil, whether I needed to feed them more during the growing season, or whether this is a normal spread of sizes.
Now I have the fun part of finding lots of different kumara recipes to use up my harvest.