Lavender

Year-round

Lavender comes from the Mediterranean, a hot, dry, rocky climate that is close to the opposite of Dallas's heavy Blackland Prairie clay. Get the site and drainage right and it can be a long lived, low water shrub. Get it wrong and it rots.

• Full sun, at least six hours a day, in a raised bed or mounded berm built eight to twelve inches above grade so roots stay out of standing clay water.
• Amend heavy clay with coarse sand, gypsum, and organic matter, or build the bed from a fast draining gritty mix instead of trying to loosen native clay in place.
• Mulch with gravel, crushed granite, or pea gravel instead of wood mulch or bark. It reflects heat, keeps stems dry, and does not hold moisture against the crown.
• Water low and infrequent once established. In Dallas, overwatering kills far more lavender than underwatering does.
• The ASPCA lists lavender as toxic to dogs, cats, and horses. The listed toxic components are linalool and linalyl acetate, with reported effects of nausea, vomiting (not seen in horses), and loss of appetite. Keep it out of reach of pets that chew on landscaping.

Summer

Summer in Dallas means intense heat and, some years, heavy humidity. Both push lavender toward stress and rot faster than cold weather ever does.

• Water deeply but infrequently, and water in the early morning rather than midday, to cut evaporation loss and avoid leaving foliage wet overnight.
• After flowering finishes, trim spent flower spikes back to the topmost set of leaves. This tidies the shape and can trigger a smaller second bloom.
• Brief wilting during peak heat that recovers by evening is normal. Wilting that does not recover points to a drainage or root problem, not a signal to add more water.
• Give plants room to breathe. Crowded plantings trap humidity around the foliage and raise the risk of leaf spot.

Fall

Fall is when North Texas lavender gets its main structural haircut, ahead of winter and next year's growth.

• Do the year's main prune in early fall, cutting back about one third of the plant's woody growth to keep a dense, rounded shape and a strong base for next spring.
• Remove dead or spent foliage and stems so the plant is not carrying disease prone debris into winter.
• Refresh gravel mulch where it has thinned, keeping it a couple inches back from direct contact with the stems.
• Hold off on heavy pruning after mid fall. Cutting into old wood too late leaves little time to recover before the first freeze.

This is the prune that most affects how the plant looks the rest of the year. Skipping it is how lavender turns into the sprawling, woody, leggy shape that reads as untended in a front yard bed.

Winter

Dallas winters are mild most years, USDA zone eight a, but an occasional hard freeze is the real risk to an established plant.

• Leave the plant's structure alone once temperatures drop. The fall prune should already be done, and additional cutting during winter dormancy adds stress.
• Before a hard freeze or ice event, a breathable frost cloth draped over the plant helps protect stems from wind and freeze damage. Do not use plastic, which traps moisture against the foliage.
• Keep gravel mulch in place through winter. It protects the crown and roots through freeze and thaw cycles better than wood mulch, which holds moisture against the base.
• Hold off on watering right before or during freezing weather. Wet soil that then freezes is harder on roots than dry soil.

Spring

Spring is planting season and the first real test of drainage, since North Texas gets heavy spring rain on top of thawing clay.

• Plant new lavender after the last frost, typically early to mid March in the Dallas area, so roots get a full season to establish before summer heat.
• After spring downpours, check that the raised bed or berm is draining within a few hours and not holding standing water around the base of the plant.
• Cut back any winter damaged, gray, or dead stems once new green growth shows at the base. This is also when to shape the plant into a tidy, rounded mound.
• Go light on fertilizer, or skip it. Lavender that gets too much nitrogen grows soft, floppy stems and fewer flowers, with more disease risk.