Best way to harvest and store kūmara
Dunsmore Gardens owner Doug Nilsson has been growing kūmara for longer than he cares to remember and, with a staff of 50, supplies his precious product to Kaipara Kumara, which in turn supplies Countdown.
And Nilsson has some tips on dealing with pests and getting your soil ready for next season’s planting.
HOW DO YOU KNOW WHEN TO HARVEST YOUR KŪMARA?
The rule of thumb for commercial growers is that your red kūmara will be ready to harvest 120 days from planting, but there is no actual day of maturity on kūmara. If you want new season or boiling kūmara, then take them out earlier, and if you want kūmara chips, leave them a while longer.
Your golden varieties tend to need longer in the ground to size up while your orange varieties can be ready from around 100 days, depending on the warmth and sun over summer. Kūmara don’t like it wet or cold.
You can also do a tickle test, where you carefully remove some of the soil and tickle the kūmara to see how big it is. And we raid a few out here and there before harvesting.
You don’t want to leave them too long in the ground because kūmara are perennials, so once you get into autumn the plant will start taking the goodness out of the tuber to support the vegetative plant. And they’ll also start to get brown-centre and rot.
When Cyclone Gabrielle went through our plants, they died on top, but a month later they all sprouted again, but the tubers were all gone. It’s an extremely tough and adaptable plant.
WHAT IS THE BEST WAY TO CURE YOUR KŪMARA?
We cure our kūmara in our stores by heat treating them, but the home grower can just leave them out in the sun for an hour or two and they’ll dry up and their skins toughen. Commercial growers don’t leave them on the ground because the birds will peck holes in them.
When we put them into a store we’ll heat cure them for possibly up to three days at about 28C and then we cool them down to 14C. During that process we have a few that we lose and that’s probably because they’ve been knocked around during the harvest – they may have got a graze or a cut so the soft spot spores get in.
Kūmara have very thin skins when in the ground and before you cure them, that’s when you have to be most careful. If you treat your kūmara roughly and throw it in a crate or bin and it gets a knock, it will go rotten on you overnight. But once they’ve cured and settled down in the shed, they’ll keep there for six months, good as gold.
HOW SHOULD YOU STORE YOUR KŪMARA?
You want to leave them in a cool dark place; you don’t want light or the’ll sprout. I know a lot of people wrap them individually in paper. We keep them stored at around 14C so it’s not cold, you don’t want to go under 10C and put them in chillers because they’ll get brown-centre and break down internally.
If you start getting as high as 18C-20C they might start wanting to wake up and sprout. The thing I will say though is that you will have to expect some rot. So store them somewhere you can monitor them and pick the odd rotten one out. I suggest putting them in breathable sacks in your garage.