Splitting the clump

You can store a whole clump intact, but splitting has two advantages. First, it lets you inspect every tuber closely and discard the duds. Second, it multiplies your stock. A clump of six tubers becomes six new plants if you divide carefully. The key is that each division must include a portion of the crown with at least one growth bud. A tuber alone, no matter how plump, will sit in the pot and do nothing.

Use a clean, sharp knife. Start by identifying the eyes on the crown. They cluster near where each tuber neck joins the stem. Once you can see them, cut down through the crown so each tuber takes a slice of stem and at least one eye with it. The cuts do not need to be neat. A ragged cut with an eye beats a perfect cut with none. Some tubers will have obvious eyes; others are ambiguous. When in doubt, leave a generous chunk of crown tissue attached.

After splitting, dust the cut surfaces with sulphur powder or leave them to air-dry for another 24 hours before storage. This seals the wound and prevents infection. Each division is now an independent plant. Label them clearly. By spring you will have tripled your dahlia count from a single autumn's lifting.