Growing Guide Lavender (Lavandula)
These aromatic subshrubs are popular in herb gardens as well as in the perennial border, and the intensely perfumed blue-violet, mauve, pink, or white flowers are treasured for drying and making potpourri. The foliage of Lavender is a standout in the garden where its silvery or gray-green hues contrast nicely with its neighbors. Lavenders thrive in the arid West, but are best grown as annuals or container plants in the South, as they do not thrive in areas of high humidity (with the exception of Lavandula dentata and L. stoechas). Most are hardy from Zones 5 to 9; Spanish Lavender (L. stoechas) is only hardy in Zones 7 to 9.
Light/Watering: Lavenders demand full sun, although afternoon shade may be appreciated in the hottest climates. Plants are very drought resistant once established, but will flower better if not allowed to dry out.
Fertilizer/Soil and pH: Supplemental feeding is not necessary as Lavender prefers a lean soil, although plants appreciate an occasional side dressing of compost. Perfect drainage is a must, especially through the winter; plants will die in wet soils. A pH close to or slightly above neutral is best, so add lime if your soil has a pH below 7.0. A gravel mulch is beneficial and helps to keep the crowns of the plants away from excess moisture.
Pests/Diseases: Both the leaves and flowers of Lavender contain strong essential oils that are not appreciated by foraging deer or insect pests. In humid climates, fungal problems may arise, but can be avoided by providing excellent drainage and good air circulation around your plants.
Companions: Lavenders are lovely as an edging in the garden and complement many other perennials, including Roses, hardy Geraniums, Catmints (Calamintha) and Shasta Daisies (Leucanthemum x superba). Varieties with silvery foliage are perfect for knot gardens, and if regularly sheared, make a fine low hedge.
Pruning: Lavender is a woody subshrub, and pruning techniques should reflect this. Do not prune in spring until new growth appears, and leave plants alone for the winter. Plants may be sheared back and shaped after flowering, but do not cut low into old wood. If older plants become unsightly, cut back by a third every three years.
Harvesting and Using Lavender: Flower spikes have the strongest scent just as the pretty little flowers begin to open. Cut long stems and gather in bunches to dry out of the sun – this will take four to five days in warm weather. Spread stems on a screen or sheet so air circulates easily. Use the stems of fresh or dried flower spikes in arrangements or remove the flowers for sachets and potpourri mixtures.
Reflowering: If old flower spikes are sheared off after the first bloom period, a second flush of flowers may occur later in the season.
Dividing/Transplanting: Younger plants handle division better than older, woody specimens. Plants may be moved in early spring, but keep plenty of soil around their roots when you dig them up.
End-of-Season Care: Do not prune back in the fall. A protective mulch of evergreen boughs may help prevent damage from winter winds in cold climates.
Calendar of Care – Lavender
Early Spring: Wait until new growth breaks from the woody stems before pruning. Remove deadwood, and shape plants. Divide or transplant if needed. Side dress plants with compost, keeping it away from the crowns of the plants. Check soil pH if your soil is acidic, and correct to a pH between 6.5 and 7.5.
Mid-Spring: As the soil warms, mulch around plants with gravel.
Late Spring: Shear plants back after flowering is finished. Supplement natural rainfall if weather is very dry.
Summer: Watch for fungal problems in areas of high humidity and treat as necessary.
Fall: Do not cut back stems before winter. In severe climates, cover plants lightly with evergreen boughs to buffer drying winter winds.