Dahlia (S)
Zone 8-10
In areas with short seasons, tubers can be potted up 4-6 weeks before last frost date with the buds just at the soil surface. Keep pots warm and moist and in a bright spot.
Planting: Plant potted tubers outside after fear of frost has passed. Lay tubers flat in holes 6” deep and cover with 3” of soil, filling in the hole later as the shoots grow. Plant 1-3 feet apart depending on the mature size of the dahlia. Cultivate the area where dahlias are to be planted quite deeply, at least 12”, to encourage a large, deep root system. Dahlias require abundant organic matter and very rich soil. After planting, fertilize once a week with a balanced fertilizer and water during dry periods.
To grow stockier plants, encourage branching by pinching off the tops of the stems. To grow the biggest possible Dinner Plate or Cactus-type flowers, pinch off all but the terminal (topmost central) bud on each stalk.
Overwinting: A few days after frost blackens the plants, lift the tubers and hang them to dry as stems may have water in them. Dust tubers with sulfur dust to prevent rotting, then lay them in shallow boxes or crates and cover with slightly moist peat, sand or vermiculite. You can also wrap tubers in several layers of newspaper.
Store them in a cold but frost-free place that stays above freezing and check periodically to ensure tubers aren’t shriveling. If dry mist them lightly with water in a spray bottle. Remove any soft or rotten roots and add dry peat moss if they are too moist.
Dividing tubers in spring: A week before your last spring frost date, spread out the tubers indoors and cover them with 1” of damp peat to encourage budding at the stem end. After 10 days, or when the buds are visible, divide each clump into sections so each new tuber has at least one bud growing.
