Planning winter storage

We have now arrived at the time of the year when we have to start planning what to do with our Cannas over the winter. Last Saturday saw the temperature drop to 8Deg Centigrade, which is low enough to start slowing down the excellent growth that Cannas should be making during September, when they come to a crescendo of flowers and new foliage.

Those with only a few Cannas to look after can decide to bring indoors into a conservatory and keep them growing over the winter, as Canna is a 52 week plant, or to wait until the frosts and move the plants indoors into a garage or shed after cutting down the foliage.

Our approach is to dig the plants out of the beds in which they are growing, using a garden fork to minimise damage, and to retain about a third of the plant, which is then planted in soil inside one of our three poly tunnels. This involves a lot of work, but will provide much new compost from the foliage and stalks.

Canna is a plant from the tropics and sub-tropics, and just being under the ground and inside a tunnel is not enough protection from the winter weather, as last year we recorded temperature of -10F in the main tunnel, so we will also cover the plants with horticultural fleece. Those with small unheated greenhouses may be able to do the same.

Others prefer to remove all soil, wash and allow to dry for a few days and then store in damp newpaper, vermiculite or perlite in dry conditions about 8F. 

Earliest winter in 30 years

Britain is shivering through the coldest start to winter for more than 30 years, the Met Office has revealed. The average temperature for the first third of December was a chilly 1.7C (35.1F)- compared to the long term average of 5.2C (41.4F), according to official figures.

One of the polytunnels in which the stock plants of the Claines Canna Collection are over-wintering, with horticultural fleece providing an extra protection from a hard winter.

The frosts and wintery showers of the last few weeks - which saw night-time temperatures plunge to minus 12.7C (9.1F) - are in stark contrast to the recent run of mild winters which have seen lawnmowers in action in December, and roses blooming in January.

The last time Britain had such as cold start to December was in 1976 - only a few months after the scorching drought summer. Then the average temperature was a chilly 0.8C (33.4F).

Climate scientists say 2008 will be the coldest year globally this decade. However, they also point out that it remains the 10th warmest year on record in the UK and that the long term trend remains rising world temperatures. We live in hope that next summer might be more typical of global warming, and not global wetting!

What makes it feel surreal is that a correspondent from Moscow is complaining that this is the warmest December they can ever remember, and they want some snow, and Bernard Yorke in Australia is complaining of too much rain in Victoria, which has had droughts for years and years. It has all gone topsy-turvy!

In the meantime, we are pleased with our new approach to keep the stock plants growing over the winter in unheated polytunnels, protected by a layer of fleece. The only attention that has been required so far was spraying with a fungicide after wooly mildew appeared in one of the tunnels.

We have not yet put this approach to the ultimate test of a January freeze lasting for weeks, which could see the ground in the polytunnel frozen to a depth where it affects the rhizomes. I hope that we do not have to! However, on reflection, I think that we may have to consider investing in some bottled gas heaters to protect against that extremity.