For longer than I can remember, I have been expanding my vocabulary of ‘horticultural slang’ as necessary to explain issues which are so rarely discussed that commonly accepted terminology has not yet been invented. Some of my slang is now actually commonly used among other horticulturists. The term ‘toupee’ originated from one of my botany professors who wore an old one which remained dark brown long after his real hair had turned silvery gray.

Now the term is used to describe an odd plant species within a formal hedge of another species. Very commonly, they originate from nearby parent plants as seedlings which are not removed; but instead mature and are incorporated into the hedge. They may also often originate as new plants which were installed to replace missing ones, but are of different cultivars or species. Even the most precise shearing will not hide a toupee.

This is why ‘volunteers’ (I did not invent that term.) should be removed rather than incorporated into hedges. Suckers and watersprouts from other species which emerge below hedges should also be removed. When acquiring replacement plants, one should be certain that the new plants are of the same species and also of the same cultivar. This may be difficult with some of the outdated cultivars, such as the old yellowish Japanese boxwood which has since been replaced in nurseries by modern, greener cultivars.

Those who release ‘mow, blow and go gardeners’ into their gardens risk other shearing problems; including the possibility that some plant species which should not be sheared will be. The ridiculous shapes which result are referred to by what they may resemble; such as ‘drumsticks’, ‘fish sticks’, ‘dice’, ‘biscuits’, etc. Many were originally functional specimen trees which were not high enough to escape the wrath of the ‘gardeners’. Victims are most commonly low branched trees which resemble shrubbery when young; such as Tristania laurina, New Zealand tea tree, purple leaf plum (low bud), crape myrtle and the various species of Podocarpus.

An office building in my neighborhood exhibits a pair of ‘drumsticks’ flanking the front doorway. They are composed of Tristania laurina and would be very suitable small trees if they had been pruned properly during the past few years. However, they now detract from the appealing architecture rather than enhance it. This is a classic example of a designer’s good intention gone bad.

Espaliers and trellised vines should not be sheared regularly, but selectively pruned to minimize accumulation of superfluous growth. Most espaliers are grown for their appealing inner structure which is best exposed with selective pruning. Blooming vines which may be sheared between bloom cycles to maximize successive bloom cycles should be pruned or severely sheared annually, usually at the end of winter.

Hedges composed of species used for their showy bloom require well timed shearing. Very often, such hedges are sheared just prior to bloom so that flowers are not permitted to develop. Severe shearing prior to initiation of bloom will allow more space for completion of a bloom cycle before the next shearing.