Lia Leendertz

Your questions answered

Part of my garden is overlooked by my neighbour, and I would like to put in a smallish screening plant. I'd like an autumn-flowering cherry, but I'm not sure how far from the house they should go. Alternatively, a tall grass or bamboo that won't trigger my wife's hay fever. Any suggestions?

An autumn flowering cherry grows to about 8m in height and spread, and should therefore be at least 4m from the house. It would be fine for your wife's hay fever. Wind-pollinated plants are the ones to avoid as they produce light, fine and particularly troublesome pollen. A rough rule is that large, colourful or scented flowers (including cherry blossom) are insect-pollinated, whereas insignificant, pale ones (including those of most trees, and all grasses and bamboos) are wind-pollinated. Crab apples are insect-pollinated and always good for small gardens, as they have more than one season of interest. Malus 'Evereste' grows to 7m, bears huge amounts of white blossom in spring and orange fruit in late summer/autumn. A female form of holly, such as the variegated Ilex 'Golden King' (which grows to 6m), produces no pollen and provides screening foliage and red berries in winter. The hawthorn, Crataegus laevigata 'Paul's Scarlet', has deep pink, double flowers, grows to 8m and is known to be a harmless tree for hay fever sufferers.

This year, I grew alliums for the first time. They had beautiful flowering heads, but the leaves were yellow and dying. I dug up one bulb, and found a brown grub. Is there a treatment, preferably organic?

Alliums flower once a year. The foliage appears first then turns yellow and dies off as the flowers appear, so yours were just doing what they're supposed to do. Try growing them through ground cover, such as geraniums, to hide the manky leaves. I don't think this is onion fly (which can cause leaves to yellow prematurely) as the maggots would be white, not brown. Dig up and inspect the bulbs at the end of the summer. If this is onion fly, the bulbs will have been tunnelled into by the maggots; if so, they should be burned.


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