It seems unhappy with this. Leucothoe belongs to the Ericaceae family, the vast majority of whose members require acid soils. For success, grow L. 'Scarletta' on acid soil in the ground or a large container. To maintain acidity, top dress with ericaceous compost annually in spring and water frequently, keeping the humus rich compost permanently moist, with rainwater to avoid lime in tap water. This cultivar is evergreen and considered hardy, although I would recommend protecting from severe frosts with horticultural fleece.
Foliage starts dark purple, changes to dark green at maturity then to bronze in winter.
It is generally a slow growing, clump-forming shrub that reaches 1m x 1.5m. No pruning is necessary. We wish to plant a couple of horse chestnuts and sweet chestnuts in the cleared area, but have heard the ground needs to rest for a couple of years before replanting. We also want to plant daffodils, bluebells and snowdrops. The area that you have cleared sounds ideal for bulb planting and transplant tree planting.