This is the question all dahlia growers ask themselves at least one time. There are at least two questions which need to be answered to be asked to make the right decision.
- What is my soil like? If it is a free draining sandy soil, it may be okay to leave them in the ground. On the other hand, heavy clay-based soil it would be safer to lift.
- What part of the country do you live in? If you live in milder parts of the country, you can get away with leaving your tubers in the ground, provided you place a good layer of mulch over them at least four inches deep Mulch is any material that is spread or laid over the surface of the soil as a covering. It is used to retain moisture in the soil, suppress weeds, keep the soil cool, prevent frost heaving in winter, and make the garden bed look more attractive. Remember one degree of frost penetrates one inch of soil.
WHEN IS THE RIGHT TIME TO LIFT?
Timing is important. Whilst the tuber should not be subject to frost, lifting them too early or even immediately after the first bout of frost is a bad idea. The tubers need to swell up and mature before they are lifted, and this usually happens after the first frost. You will know when the first frost has got them, as they go mushy and black, the foliage, stems and flowers of dahlias are extremely sensitive to frost.
Cut the foliage back to about six inches above the ground. Use a fork in light sandy soil and a spade in heavy clay-based Soil. Once lifted place in a well-ventilated frost-free place upside down (stalk to the ground) and allow to dry.
Once dried, its time to trim the root hairs of the tuber.
Once dried and trimmed, store them in a bed of dry compost or paper and keep them frost free. Check the tubers very now and then then and remove any rotting parts. Cover with hessian or horticultural fleece if a cold snap is forecast