Every year I tell myself the dahlias will be fine left in the ground, and every spring I remember the one winter they were not. A wet January turned a whole row of tubers to grey mush, and the border looked bald well into July. Since then I lift my favourites, and the ritual has become one of the quiet pleasures of late autumn.
Whether to lift at all. In a light, free-draining soil in the south of England, tubers under a thick mulch often survive. On heavy clay, or anywhere that sees hard frosts and sodden winters, lifting is the safer choice. If you have an expensive or sentimental variety, lift it regardless.
When to lift. Wait for the first frost to blacken the foliage; this signals the tubers to go dormant. Cut the stems down to about 15 cm, leave the clumps in the ground for another week, then ease them out with a fork, starting a good 30 cm from the stem so you do not spear the tubers.
Cleaning and drying. Brush off loose soil rather than washing the clumps; a little soil is harmless, a lot of water is not. Turn each clump upside down for a week or two in a frost-free shed so the hollow stems drain. Label every clump now. You will not remember which is which in March.
Storing. Pack the clumps in crates or cardboard boxes in barely damp coir, dry sand or shredded paper, stems up, with air gaps between them. Keep them somewhere cool, dark and frost-free, around 5 degrees. A garage, cellar or unheated spare room is ideal. Check them once a month: shrivelled tubers need a light misting, and any that are soft or mouldy should be cut out before the rot spreads.
Starting them again. In March, pot the clumps into compost in a frost-free greenhouse or on a bright windowsill. When shoots appear you can take cuttings, or divide the clumps, making sure each piece has a bit of crown and a good tuber. Plant out after the last frost, usually mid to late May.
Everything I use for this lives on my landing page: crates and trays, labels, a good pair of secateurs and a sturdy fork. Follow the link in my bio to find them.
A box of sleeping tubers on the shed shelf is a small promise of August. Lift them this month, and you will be cutting armfuls for the vase next summer.
My favourite cottage garden tools and supplies are collected on my English Cottage Living landing page, from seeds and sowing supplies to greenhouse and tool shed essentials and planters and pots.
Transparency notice: this post may link to affiliate products via my landing page; I may earn a small commission at no extra cost to you.
