Empty plot over the winter - to cover or not

Just been out walking the dog and had a ponder on your dilemma Scarlet.

If I had an acre of land where my only intention was to grow dahlias in summer ........Without knowing contours of land and shape of land I am just envisioning half a football pitch?

Yes, think half a football pitch! The dahlia growing is only a small section. But a time consuming one.

I have a large walled garden, a veg plot and a min "orchard".
Lawn for very active collie and husband that has set up a assault course for dog. 
Lawn also used for ball games, football and archery.
This is edged on 3 sides with deep flower borders - 15- 10ft in most places. A pond.
Small "orchard" - a section given over to fruit trees - 4 pears 10 apples. Mostly planted last year after my walnut tree was felled.
3 large cob nut bushes.
This is edged in a native mixed hedge. 
Veg plot- 20ft Green House, 12 Ft GH, a shed
Large raspberry patch/maybe 30ftx10ft.
10 currant bushes. Approx 6 gooseberry bushes/ hedge. Area with tayberries. Several rhubarb plants.
 With an area taken over for growing dahlias. 
This size - I just want to cover withnon growing stuff it to reduce my Spring work and save my back.