Crop Focus: Kūmara

Growing your own tipu/tupu!

We have been incredibly fortunate to have Darren Gray growing an abundance of this wonderful crop for us on Aotea - but alas not for much longer. Many folk on Aotea also grow a small patch for themselves and it is an exciting crop to grow. We have the perfect climate. 

It may be time for more of us to think about growing our own.

However, there are several things to consider before dedicating a portion of your growing area to kūmara. 

Pests

There are several pests which love them:

Rats: number one threat to a kūmara crop. And on Aotea we have them in abundance. When the kūmara are forming their tubers, the vines smother the soil, giving perfect cover for rats hunting for new food to sniff them out.They start digging and then eating out the tubers.  Their mates join the party and before you know it, your kūmara crop has been ruined.  There is nothing more discouraging than to dig up what you anticipate to be a gorgeous huge kūmara to find it has been completely hollowed out. 

So if you are going to grow kūmara, you have to be prepared to have several rat traps and bait and monitor them daily. Great baits for rats include sunflower seeds, pumpkin seeds and peanut butter. Poison is not necessary. 

• Wireworm: This  is the larva of the click beetle.  These long, black, shiny larvae tunnel through the kūmara tubers leaving their frass behind.  The kūmara will still be edible and you can cut around the damage, but they cannot be stored as the damage will cause them to rot.

The wire worms are more of a problem around late March through April. You can avoid damage by harvesting the kūmara early. However this will be at the sacrifice of size, as the kūmara double in size from one month to the next  at this time. 

• Care in Harvesting: In the process of harvesting great care has to be taken not to damage the tubers, as  again, any damage will cause them to rot in storage.

• Storage itself has its own challenges. The kūmara must be in perfect condition and well cured. They must also be stored in such a way as (a) to protect them from rats and mice and (b) to keep them from  drying out which causes them to wrinkle.

So if you are still keen here’s how to start the journey!

Growing Kūmara

Kūmara are a  long term crop!!

Think of it this way: the kūmara is an incredible store house of energy in the form of complex carbohydrates and fibre… that energy comes from the sun… so they need LOTS of sunshine hours to produce those delicious tubers!

The timeline for Kūmara is:

August/September: grow tipu;

October to November: plant tipu;

February to April: harvest (and keep weed free in between and be ever on guard against rats!)

(The moon calendar and Maramataka  give more specific times.)

Growing your own kūmara tipu 

Tipu are the shoots that kūmara will grow from the little eyes on the tubers. Each eye on the tubers has the potential to grow up to 12 tipu so 2-3 good kūmara with plenty of healthy eyes can potentially generate hundreds of tipu!

The tipu are removed when they have developed roots and are a certain size and planted when the soil is truly warm (18 C) - usually from mid October to early December.

Kūmara need 5 1/2-6 months to reach a good harvestable size, so the later you leave it to plant them, potentially the smaller the harvest will be. You want them to be vining well over the hot summer months of December, January and February.

These notes on growing tipu are summarized from an awesome article by Neville Pomare, a Māori organic grower from Wairoa, in the 1999 edition of Harvests, a biodynamic magazine. As Neville says, this was the way his family grew tipu and there will be other ways too.

Selecting kūmara from which to grow tipu was traditionally done at harvest time and those kūmara would be very carefully stored for the next season’s planting. No eating! Using store bought kūmara from which to grow tipu may not give the best results, as you know nothing about the mother kūmara’s growing habits. But most of us probably haven’t got our own seed kūmara  - so if you are using store bought kūmara, choose healthy, blemish free kūmara, with good shape and plenty of eyes.

Making a Pārekareka (Kūmara tipu sprouting bed)

Dig out a bed about 8-14 inches deep, walled with untreated timber and with a glass or plastic frame over the top- like a mini glass house over a raised bed. For smaller home plantings of kūmara for tipu,  fish bins, mussel buoys and other containers can be used instead (just make sure they have drainage holes!!) 

The bed is filled with a layer of horse and cow manure about ten inches deep mixed with a little hay, (to generate heat) with a 2-inch layer of pumice over the top. The kūmara are laid out sideways over the top allowing 2-3 inches between the tubers. Then the tubers are covered with another 1-2 inches of pumice, and the lid of the hot frame closed. Do not water at this stage.

After 2-3 weeks the tipu should start to show. Water them now, enough to dampen everything down. Once most of the tipu are through, layer another inch of pumice over the top. The tipu will  form roots as they grow through the pumice, which provides aeration and holds enough moisture to encourage rooting.

Repeat until kūmara seed are covered in around 5 inches of pumice, and the actual shoots are around 4 inches long (ideally 4 inches rooted, 4 inches shoot). Keep up with the watering and monitor the heat build up as it warms up. It may be necessary on sunny days especially to lift the lid up to avoid steaming the plants! Also make sure to have rat traps in the area – rats right now would LOVE a high energy feast on kūmara…

You can also order tipu  from specialist growers up North from October on, but make sure they are sent on a Monday so they aren’t sitting around over a weekend when they can rot in storage.

Make sure your growing beds are ready!!