About Dahlia
A clump of swollen roots joined to a woody crown. New shoots arise only from buds on the crown at the base of last year's stems, not from the tuber alone.
Depth and spacing
Typical range: 10-15 cm deep and 45-60 cm apart. A general rule is to plant at two to three times the height of the tuberous root; check the label for your variety. The drawing is to scale for 12.5 cm deep and 52.5 cm apart (the size of the organ is illustrative); try your own measurements.
When to plant
Tender: start indoors, plant out after frost. Start indoors: 6 weeks to 3 weeks before your last spring frost. Plant out: from your last spring frost to 2 weeks after. These are rules of thumb for the northern hemisphere. Enter your frost dates for real dates.
Dividing and propagating
Divide in spring when the eyes start to swell, cutting so each piece has part of the crown with at least one bud and a tuber. Basal cuttings from shoots are the alternative.
Lifting and storing
Wait for frost to blacken the foliage, cut stems to 5-15 cm, lift, dry upside down and store in crates covered with dry compost or similar in a cool, dark, frost-free place. In milder places a thick mulch may do.