Stonecrop (the larger, ornamental Hylotelephium, formerly Sedum spectabile) produces flat-topped clusters of tiny star flowers in pink, red, or white from late summer into autumn — a valuable perennial that provides structure, nectar, and cut material late in the season. The fleshy, grey-green foliage is attractive from spring through summer, and the dried seed heads stand handsomely through winter.
Cut when the flower heads are fully coloured. They last well in water and dry beautifully in situ on the plant as winter progresses. Leave the dried heads standing rather than cutting back — they provide architectural interest and structure in the winter garden.
Crown Rot
Lower leaves yellow and wilt; the base of the rosette turns brown and soft, sometimes with white fungal threads at the soil line. Plants collapse in wet conditions.
Remove and destroy affected plants. Improve drainage and avoid overhead watering. Do not mulch directly against the crown. Space plants for airflow and avoid replanting in the same wet spot.
Aphids
Clusters of small soft insects on new growth and flower buds.
Knock off with a strong jet of water. Ladybirds and lacewings are natural predators. Insecticidal soap as last resort.
Mealybug and Scale Infestation
White, cottony masses or small brown bumps on stems and leaf undersides, often with sticky residue and sooty mold.
Wipe off light infestations with alcohol-dipped swabs or a strong water spray. Treat heavier cases with horticultural oil or insecticidal soap, and remove badly infested stems.