Care of Lavender Plants in the Pacific Northwest

Suitable Varieties

• Three basic types of lavender are best suited for growing in the Northwest, according to Oregon Lavender Association. English lavender (Lavandula angustifolia), a hardy plant valued for its sweetly fragrant blossoms, is the most commonly planted species. Lavandin (Lavandula intermedia), also known as hedge lavender, is nearly as hardy as English lavender. The plant, which displays long stems and spiky clusters, is a good choice for areas with warm, humid summers. Spanish lavender (Lavandula stoechas) is a showy landscape plant with deep blackish-maroon, pink or purple flowers, depending on the variety. Spanish lavender is more tender than English and hedge lavender, and may not do well in USDA zones 5 and 6.

Soil Improvements

• Lavender benefits from application of 3 to 4 inches of compost or composted manure at planting time. The plant prefers slightly alkaline soil with a pH of 6.4 to 8.2. If the soil is acidic, lower the pH by applying lime at a rate of 5 pounds for every 100 square feet of planting area. Dig the lime into the soil around the plants in fall, preferably just before a rain. Otherwise, water deeply after applying the lime.

Maintenance

• To promote continued blooms all summer, snip off blossoms as they wilt. Prune the plants in early fall to promote healthy growth for the coming year. Don't trim too deeply. Leave old, woody growth in place, plus 1 or 2 inches of green growth, as old wood rarely produces new growth. Repeat in early spring. Avoid crowding and thin as needed to improve air circulation.

Tips

• Established lavender plants are drought-tolerant and require no supplemental watering, notes Oregon State University. A 2-inch layer of light-colored builder's sand or crushed oyster shells helps to moderate soil moisture and temperature and also reflects sun and warmth to the plant. This is helpful, as heat enhances the aroma of the blooms.