Lavender

More lavender plants die from wet feet than from cold. This is the most important thing to know before planting, and it runs counter to the way most gardeners think about plant loss: they assume it was the frost, when it was actually the January rain sitting on the crown for three weeks. Lavandula angustifolia can tolerate temperatures down to about 0°F if the soil around its crown is dry. That same plant in soggy clay at 28°F may not make it to spring. Drainage is the primary variable.

Lavender came from stony, alkaline Mediterranean hillsides with fast-draining soils and low rainfall. In the garden, the soil preparation is where success is decided. Work in generous amounts of coarse grit or gravel before planting — not peat, not compost in large quantities, just drainage material. If your native soil is clay, raised beds are nearly mandatory: a 6-to-8-inch raised area with a grit-amended mix will keep lavender alive through winters that would kill it in the flat ground below.

Start seeds indoors 10 weeks before the last frost, or — more practically — buy transplants. Lavender is notoriously slow and inconsistent from seed; germination can take three to four weeks, and not all seeds are viable. Most gardeners buy named varieties as transplants. Set them out 2 weeks after the last frost, 24 inches apart. In the first year, expect modest growth while the plant focuses on root establishment. Do not harvest heavily in year one.

Annual pruning is how lavender stays productive and avoids the bare, woody collapse that ends most lavender plantings. Prune in early spring, just as new growth emerges, by cutting back by one-third to one-half — enough to shape the plant but not so far that you cut into old, bare wood. Cutting into the woody base below any green growth will not produce regrowth; lavender does not break from old wood the way sage does. Prune every year without fail. A plant that is never pruned becomes a ring of green tips around a dead center within four to six years.

The lavandin hybrids — Lavandula × intermedia — grow larger and bloom more intensely than true angustifolia types. Grosso and Provence are the most widely grown lavandins; they produce more fragrant, more abundant flowers and are preferred for cut flowers and sachets. They are, however, slightly less cold-hardy than Hidcote or Munstead. In zone 5, stick with Lavandula angustifolia selections. Phenomenal is a lavandin with unusual cold hardiness and strong disease resistance, and it is worth considering where winters are cold and wet.