Tubers, when to lift?

It is best to wait until the plants have succumbed to frost as the sap is driven into the tuber making it nice and solid aiding long term storage.  However, if you intend propagating then the tuber needs time to rest before being started off again.  As I'll be starting mine off in mid-January I'll be lifting now although they are still in full flower; damping off quickly and colours faded though.

To lift or not to lift?
Tubers will survive the winter cold, unless it's permafrost! if they are well mulched.  However, this raises the question of whether one grows from tubers or plants.  We raise all our premium cut flowers from plants; the stems are stronger, the colour is better and the bloom is a better size.  So, if your are exhibiting you should be raising your plants each year.  However, if you want a colourful display in the border then using tubers is good as they will produce a profusion of blooms all summer long; as long as they are dead-headed regularly.

I would caution against leaving tubers in the ground year after year though.  After time the plant will weaken, lose colour, lose stem strength and revert to type.  We have all seen those plants with faded, daisy eyed blooms on drooping stems; old tubers.  It is better to lift and split them, this will prolong their life.

Dahlia jobs in November

November is a tricky month lately; last year deep in snow, this year still in full bloom, although getting a little tired.  If your dahlias, like mine - see photos - are still in bloom and untouched by the frost, it is as well to leave them for a while in the hope that there will be a frost soon!  Frosting of the foliage kills the capillaries forcing the sap into the tuber both swelling them and enriching with the sugar content.  (Remember about the sugar content?  It is why wasps eat the stems)

Two images taken a week ago, the filed looks pretty much the same today.  I am still cutting selectively, a number of cultivars are still going well with fully formed blooms and good colour.

If you lifted your tubers last month it is time to check that the stems have drained, face them upwards and remove as much soil as possible.  When dried, lay the tubers in shallow boxes, dust with flowers of sulphur and keep in a frost-proof room.  When the weather is suitable burn all the foliage to destroy any possible disease being carried.  Ground preparation: manure and dig over roughly to allow the frost to break the soil down.