Hedging Plants – Thuja

Description and uses – This evergreen conifer has bright green, very hardy foliage and can reach a height of 20 metres in its native habitat – cultivars now exist of golden and blue forms too. It is indigenous to North America, forming dense forests. and is grown in European gardens and parks. The branches are short, the lower ones horizontal, the upper ones crowded and forming a dense, conical head. The opposite pairs of bright green, acute leaves resemble overlapping scales, and have a strongly aromatic odour when crushed. The minute, solitary terminal flowers appear from April to July and are yellow or greenish in colour. The small cone is pale green when young, light reddish-brown with pointless, thin, oblong scales when mature. This is a conifer that likes wet soil as long as it is free draining, so it does well over old building rubble. However it is tolerant of dry dusty sites and of atmospheric pollution in towns and is easily transplanted.

Maintenance and problems – For hedges, trim in August but be aware that thuja plants cannot regenerate from old wood. Pruning is not normally necessary and any pruning that is carried out should be done with care to maintain hedges for to ten feet tall when it makes a very dense hedge Leaf blight causes brown spots on the leaves in late spring when the affected foliage appears scorched, then drops. Juniper blight may attack Thuja. Tip blight is of more concern on T. orientalis, especially the golden foliage types. The foliage at the tips of the branches turns brown in late spring or early summer. The only treatment is to cut away the affected areas.

Hedging photograph by ndrwfgg, used under a creative commons attribution licence

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