In a garden chorus or solo, dahlias create a singular sensation.
CARING FOR DAHLIAS
Since the discovery of Dahlia pinnata and D. coccinea, parents of our modern hybrids, in Mexico and Central America, and their arrival in Spain, in the 1780s, more than twenty thousand varieties of dahlias have been named. This abundance results in part from a natural tendency to hybridize, but it's also a testament to wave after wave of popularity, interspersed with lulls when other flowers took the spotlight. The thing about dahlias is you can't help but give in to their exuberance. If you don't smile right away when you see them, you probably shouldn't grow them. But if you do smile-and that puts you in the majority-there's no substitute for having a few around. Or a few too many.
PLANTING After the last frost, once soil is warm and workable, plant tubers with their growing points (eyes) up, 4 to 6 inches deep and 18 to 36 inches apart. Rich, well-drained soil in a sunny spot protected from wind is ideal. Water after plants are 6 inches to 1 foot tall.
STAKING Most dahlias need support. Before planting, drive a stake at least a foot into the ground. Tie off every foot or so as dahlias grow.
FERTILIZING A week or two before planting, mix well-rotted manure, compost, or 5:10:10 fertilizer into soil. (Note: High-nitrogen fertilizers promote foliage but reduce flower yield.)
PRUNING Deadheading is key for continuing bloom. When plant is 6 to 8 inches high, remove all but the strongest one or two stems. Pinch these back. For maximum bloom size on large flowered varieties, remove all but a few buds.
PESTS Stems shorter than 6 to 8 inches are vulnerable to slugs and snails; pick them off. Control heavy aphid, earwig, or spider mite infestations with insecticidal soap.
STORAGE Dig up tubers right after frost blackens the foliage. Cut stems to a few inches; wash off soil. Dry tubers for a day, stems down. Place in a cardboard box and cover with slightly damp sawdust or vermiculite. Store at about 40 degrees. Inspect in January; if tubers are shriveling, mist the sawdust or vermiculite with water until they are barely damp.
CUTTING Flowers that are cut in full bloom (not buds) tend to last the longest.