Am I too late to prune a plum? Why hasn’t wisteria flowered? Read on…
TREES & SHRUBS
A This premature discolouration of the foliage could be a sign that there is a problem with the roots – either drought, which is quite common, or waterlogging. If the soil is too wet, it suffocates the roots and they can’t take up water so the foliage wilts and discolours.
Honey fungus is a possibility as forsythia is prone to this disease. If you see honey-coloured toadstools growing at the base in autumn, it is the likely cause and the shrub will eventually die.
But in this odd season, some shrubs adopted autumn colour early. Give it a general fertiliser like chicken pellets in spring to boost growth.
A Isuspect your tree is Albizia julibrissin (Persian silk tree), which can grow and flower in warmer and drier areas, such as in the south east. It’s not reliably hardy in most of the country, nor is it a long-lived tree. It needs a mild winter and hot summer to grow and flower well. It is prone to dieback, especially in cold, wet weather and these dead and dying branches should be cut out.
A The leaves on your ‘Lavinia Maggi’ are rather twisted but they are dark green and otherwise healthy and there are flower buds ready to open next spring. It seems to have made good growth this year and the twisted leaves may just have been the result of the hot and dry weather in June.
A The notches eaten from the edges of the foliage of your golden privet are caused by adult vine weevil. These nibble the edges of the leaves of many evergreens but the damage is largely cosmetic and they don’t do much harm. However, it means that they will be laying eggs in the soil and the grubs will be eating the roots of herbaceous plants such as heucheras, primulas and cyclamen.
Gorgeous gentians
AGentians come from many areas of the world and their requirements and flowering times vary hugely. Rocky Diamond (‘Gento’) is a hybrid of the Asian Gentiana scabra and generally flowers in late summer and autumn. It is a compact plant that can flower for several months. Like many Asian gentians it prefers an acid soil and needs moist compost, whereas many European alpine gentians demand perfect drainage and prefer alkaline
