When to plant English lavender 'Munstead'?

Lavandula angustifolia 'Munstead' thrives in full sun and demands excellent drainage, so choose a spot that receives at least six hours of direct sunlight daily. This compact lavender tolerates sandy soil, loam, and chalky conditions but will sulk or rot in heavy clay or anywhere waterlogged. If your soil is dense, work in plenty of horticultural grit or sharp sand before planting—aim for at least a third grit by volume in the planting hole. Plant in March, April or May for the growing season ahead, or in September and October so roots establish before winter. Space plants 40 cm apart centre to centre; they'll knit together into a low, aromatic hedge within two seasons. Dig a hole no deeper than the root ball—lavender resents being buried too deeply—and slightly wider. Tip the plant out of its pot, tease out any circling roots gently, and set it so the top of the root ball sits level with or just proud of the surrounding soil. Backfill with the excavated soil mixed with grit, firm gently with your hands, and water in well to settle roots. After planting, water every few days for the first fortnight if conditions are dry, then taper off; once established, 'Munstead' needs very little supplementary water. A thin mulch of gravel or grit around the base helps suppress weeds, reflects light up into the foliage, and keeps the neck of the plant dry, reducing the risk of fungal rot. Avoid organic mulches like compost or bark, which hold moisture against the stems.