Q How should I plant lavender?
A Lavender plants grow quickly, so it’s fine to start with a 9cm-sized pot. Plant in well-drained soil in a spot that gets full sun for most of the day. If you have heavy or clay soil, either improve drainage by adding plenty of well-rotted compost or some grit at the base of the planting hole, or grow lavender in pots instead using compost and grit as you would if it was going in the ground. Water your plants until they’re established.
Caption: Plant lavender in a sunny spot in well-drained soil
Q How do I prune lavender?
A Lavender thrives in poor soil, so there’s no need to add any feed. To keep them compact, trim lightly in either late summer or spring. Remove old flower spikes and the top 2-3cm of growth.
Don’t prune lavender into old wood that hasn’t got leaves as it won’t regrow. It’s best to replace old, woody plants. You can take heel cuttings very successfully, so there’s no need to buy a new plant if you don’t want to.
Light pruning helps to keep plants compact and rounded, rather than leggy and bare at the base, but advice varies about whether this should be done in late summer after flowering or in spring. For the Which? Gardening magazine trial, we pruned two plants of each variety in late summer when flowering finished, and the third in spring, just as plants started to grow. We used shears to trim away the old flowering spikes and the top 2-3cm of leaves. Surprisingly, the timing of pruning made no difference to the shape, amount of flower, or when the plants bloomed, so you can do this job at either time of year.
Caption: It doesn't matter if you prune lavender just after flowering or in spring
Q Which pests and diseases affect lavender?
A Lavender roots can rot in wet or heavy soils, so if plants start to die off in sections, check the drainage and see if it can be improved.
Rosemary beetle can attack leaves and flowers. Damage is caused by larvae and adult beetles, and is usually seen in spring or late summer. The larvae are off-white, while the adults have iridescent green shells with purple stripes.
Plants can cope with a light infestation, which can be removed by hand. A heavier infestation may need to be sprayed with an insecticide when plants are not in flower.