Over-wintering Bananas workshop

Our Ensete ventricosum stock has grown brilliantly this year. We’ve one in the seating area, another two in the walled garden and several more in containers around the garden. The largest have reached 3.5m in height. We’d really like to plant out more in the walled garden next year where they’ll be even bigger. But first we need to get them through the winter.

These Ensetes originate from Ethiopia’s highlands although they’re now found more widely in East Africa where they are still an important subsistence crop. In Africa they grow to 10 metres in about 7 years before flowering – they are monocarpic and die after flowering. But here in the UK we are limited by the size that we can protect in the winter.

That’s because these bananas are very tender. At our banana workshop it was easy to see why. Squeeze the petiole (leaf stem) of E. ventricosum and a fountain of water will emerge.

These plants are perfectly designed to collect and store water with each leaf draining into a gutter along the petiole leading to the pseudostem. If the ambient temperature drops below 4°C or worse freezes then the plant’s vascular system can’t operate and when the temperature rises and the water expands again it bursts the cell structures. And that would be the end of the plant. So we need to take steps to both keep the plant above its minimum temperature and to slow down its metabolism.

Errol removes leaves whilst Diane supports the petiole

Autumn coolness and declining light levels help here but we also take physical steps to slow the plants down and dry them out.

First we cut off all but two of the leaves. This needs to be done sensitively as bananas are  not trees and don’t have a trunk or indeed any woody structures. They’re just big herbs springing from a corm or swollen underground stem that serves as a storage organ to survive winter or other adverse conditions such as summer drought. Just like a Gladiolus or Crocosimma and many Araceae such as Taro.

What might look like a trunk is in fact a pseudostem comprised of overlapping petioles. So each leaf forms a part of the pseudostem. Where we cut each the petiole will certainly begin to dry out and if this leads to a breach of the pseudostem the plant will die. So we cut the leaves about halfway from the stem to the beginning of the leaf.

Next we dug up the plant and pruned the roots to within around 10cm of the plant’s corm. Without leaves the plant has limited photosynthetic ability and without many roots it can’t take up much moisture.

We drain the plant by keeping its roots above its stem for a few days and then pot it up into a very free-draining compost mixture comprising 80% horticultural grit. This keeps the corm dry as when it is moist it is likely to rot.

On the horticultural gurney en-route to the greenhouse

The internal structure of a leaf and the 'gutter' formed along the petiole

 

Once in the warm, dry, protected shelter of the greenhouse they should be OK. But if we have snow we may need to take further actions to protect them. 1 down and seven to go…

When cutting the leaves it was easy to see the internal structures of this important source of carbohydrates and fibre.

These charming films show how they are used by Ethiopian families as a subsistence crop in a sustainable way. Every part of the plant is used and plantations are made as permaculture-like forest gardens.

Here’s how.

 

 

 

All photos credit Alison Alexander.

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