Ask Alys: your gardening questions answered

We want a small tree under 2.3m at maturity, with a single trunk, a neat 150cm crown, blossom in spring and no berries. It should be evergreen. If it doesn't produce attractive flowers, we'd like ornamental leaves. It's for a small patch of turf in our paved front, where it will get plenty of sunlight; the soil is clay. I hate to break it to you, but that tree doesn't exist. But I can get close: the strawberry tree, Arbutus unedo , is small with white flowers, evergreen foliage and lovely-coloured bark. And in October you may get fruit. Personally, I'd go for an acer. It's not evergreen and has no pretty flowers, but there is beautiful bark for winter interest, spring foliage and autumn colour to die for. Dwarf forms of Acer palmatum will keep to under 2m and look lovely in a courtyard setting. They won't mind the clay if you add grit to aid drainage. Or how about a standard shrub? A standard Mahonia x media (yellow spring flowers, evergreen pinnate leaves) or a Viburnum henryi (white flowers, bronzed foliage in winter) will, with pruning, stay within your height restrictions.