Why have my dahlias failed to flower?
Q This year my dahlias looked perfect, with large abundant blooms. I thought they were going to look amazing, but to my dismay all the blooms wilted and rotted away before they opened. Could you tell me what went wrong and how to prevent it from happening again?
A. Hill, Northern Ireland
A The usual reason for dahlias failing to open is heavy rain, which soaks petals and causes them to decay. Thankfully, it won’t affect your plants’ general health. Leave them for now and in late October or November, whenever their leaves are blackened by the first frosts, cut back the stems to 9in (23cm).
If your soil is light and free-draining, and your garden sheltered and not prone to hard frosts and snow, you could leave your dahlias in the soil.
Mulch the roots well with well-rotted compost or manure, or bark chips, and they should survive winter. If very cold conditions are forecast it may be wise to anchor a cloche over the mulches as extra insulation.
If your soil is heavy and tends to hold onto moisture in winter, I would lift your dahlia tubers, dry them and store them in trays of dry sandy compost somewhere dry and frost-free. If they are in pots, they can stay there or, again,
