Will a willow hedge bring too much trouble?
The autumn colour of stagshorn sumach has been truly spectacular this year, outstanding in a year of exceptional autumn shades that so many people have remarked upon and enjoyed. The colour show on sumach lasts for many weeks, often beginning to show purple in late summer. The purple slowly washes out to rich crimson, while shaded leaves slowly turn to yellow and orange.
Stagshorn sumach is a very distinctive large bush or small tree with spreading angular branches. The common name refers to a stag's antlers as can be clearly seen when the leaves fall and the branches are bare. The branches are relatively thick and there are not so many branches on the tree. The leaves are divided into two rows of leaflets.
Older plants colour best, the fast-growing younger ones not colouring so well. Heavy soil tends to make the sumach quite leafy and vigorous and reduces autumn colour - and colour is not as good after a dull, wet summer. Plant it in well-drained soil and in a good, sunny position. The best colour is provided on well-drained soils of medium fertility. If the soil is extremely dry and poor in nutrients, the show of colour can be very good but it will be short-lived. The plant will stay much neater and more manageable on light soil, not growing as large. Some potash fertiliser will help autumn colouring on soils that are heavy clay.
After the leaves have fallen, the old flower heads remain. These are wine-coloured and velvety, cone-shaped and held upright at the tips of the branches. As winter progresses, the flower heads eventually fall off.
Sumach has a tendency to throw suckers when the roots come near the surface. When a sucker is established a few years, it is easily lifted and moved to make a new plant. Apart from the beauty of the tree, and its wonderful autumn colour, this ease of propagation has ensured that it was passed on countless times to many friends and neighbours. However, the suckering tendency can be a nuisance in a flower border, and the only way to control suckers is to chop them out with a spade when still small and to firm the soil down hard where they were cut out.
Do not use weedkiller on the suckers as it can travel back into the parent tree and damage it. However, the spread of suckers in a semi-natural setting can be very effective, if there is plenty of space available.
Q: A section of my garden is very damp and sometimes waterlogged. I was thinking of planting a living willow hedge to dry it up, but have concerns about the roots and their effect on my house. Are the roots invasive? Is a living willow hedge safe for a suburban garden? P Brennan, Co Dublin.
A: Willow likes moist ground but does not magically dry up an area of ground that is prone to flooding. In any case, willow is very fast-growing and lot of work to keep clipped as a hedge - generally too big for a suburban garden. You would be better to dig out a soak-away and try to drain the area of ground directly.
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