Floret Farm's discovering dahlias A guide to growing and arranging magnificent blooms

Benzakein (Floret Farm's A Year in Flowers), founder of the Floret flower seed company and farm, delivers a comprehensive and enthusiastic guide to planting, growing, harvesting, and displaying dahlias. She begins with a detailed overview of the flowers and provides a size-based classification system that ranges from the "cutest variety" of pompons at two inches in diameter, to the giants measuring more than 10 inches. She also breaks down the plants' varying shapes (peony, ball, and orchette) and colors (pink, orange, white, and red). Among growing and care advice, Benzakein offers tips on sunlight (direct sun six hours a day is a must), space (three feet on either side), and soil maintenance (soil tests are well worth the trouble, she advises). As for harvesting, the flowers should be cut when they're almost fully open, and gardeners interested in selling their plants should cut long stems, which are better for arranging. Experienced gardeners will appreciate Benzakein's rundown of such advanced techniques as propagation and hybridizing. Anyone in search of a guide to dahlias need look no further. Agent: Leslie Stoker, Stoker Literary. (Mar.)