PROBLEMS SOLVED
When will iris plants flower? Why are raspberry leaves yellow? Read on…
Sunny side up
AYour peony is a special and expensive Itoh peony, which is a cross between herbaceous and tree peonies. The ideal spot is one in full sun, in good soil, though part shade is suitable – you will just get fewer flowers. They can take a year or two to settle down and then need little or no attention apart from cutting back the dead, woody stems in winter. Your plant looks – or looked – very healthy but you should not be dividing them when in leaf – and the root damage may kill the plant.
Q How do I prune a young ‘Iceberg’ rose?
A Cluster-flowered ‘Iceberg’ roses are not pruned as hard as large-flowered kinds. Once these flowers have faded, prune back the shoots to just above the uppermost fully grown leaf. This will encourage new growth and flowers. Then next March, prune back most of this year’s growth to two or three buds. Don’t forget to feed because roses are hungry and benefit from regular feeding.
Q Why has climbing hydrangea never flowered in five years?
A Like many climbers, Hydrangea anomala petiolaris ‘Flying Saucers’ doesn’t bloom much while it’s ascending its support. Only when mature will it produce the horizontal shoots on the framework that carry the flowers. Try to fix the main shoots to the fence and avoid pruning back if possible. There’s no need to feed this healthy plant as it’s growing in the soil.
Q How can I stop a blackfly outbreak on hibiscus?
A It’s not common for hibiscus to be so badly affected with blackfly and insecticides control the problem. Flowers are produced on new growth, albeit quite late in the season, so there’s still time for blooms. Give a general feed in spring to promote healthy growth, especially after pruning, although this won’t necessarily discourage blackfly. Such a bad infestation is by no means inevitable and hopefully won’t occur again.
Aster anomaly
AChina asters (callistephus) are prone to several fungal diseases and pests. Wilt disease is a common problem when asters are grown frequently, but your plants do not appear to be wilting. They may be affected by aphids, which cause leaf distortion and
