Pruning Techniques And Terminology

Shearing:  Is the removal of all the growing tips off of a shrub or tree using a hand or electric shear. It is generally used to create a denser plant with a more formal look, such as hedges, screens, topiaries and borders. Boxwoods, yews, cedars, privets and some junipers respond well to this type of pruning. Many shrubs however, do not prosper from this type of pruning. For them it tends to destroy their natural shape and can diminish their flowering. Also the dense new growth formed at the tips of the branches tends to block air and sunlight from reaching the inner and lower portions of the shrub, causing dieback.

Renewal Pruning:  Involves cutting a shrub back to about six inches above the ground. The technique is used to restore a badly overgrown shrub. The best time to carryout this type of pruning is in late winter or early spring, regardless of whether it is a spring flowering type. This time frame will allow for the longest possible recovery period before the onset of winter. Not all shrubs can handle this type of severe pruning, but a few candidates for renewal pruning include glossy abelia, barberry, blue mist, forsythia, honeysuckle, cotoneaster, ninebark, potentilla, lilac, spirea, and weigela.Renovation Pruning:  Is used to restore a declining or over grown shrub. It involves the removal of one-third of the old, mature stems to ground level. New growth (that was produced during the previous season) is also pruned back at this time to different lengths. This technique is less severe than renewal pruning and less taxing on the shrub. Many deciduous shrubs respond well to this type of pruning. Some shrubs like forsythia, dog wood, rose of sharon, honey suckle, lilacs, bridle wreath spirea and weigela’s respond particularly well.

Pinching Candles: Candles refers to the new, soft growth put on by coniferous trees such as pines, spruce and firs. It may be partially pruned back yearly to help maintain a more compact and densely branched habit. For pines new growth occurs only once a year from terminal buds located at the tips of the branches. Pinch out 1∕2 to 2∕3 of this new growth  by hand or with hand pruners (although pruners will cause a slight browning at the tips of the branches). Do this when the candles are approx. 2” long and before the needles expand in late spring. Do NOT cut the branches back beyond this new growth as future growth for that branch will be stopped.
Spruce and Firs similarly put on new growth just once a year. They differ from pines in that both terminal and lateral buds produce new growth.  This allows for pruning further back on the branch. Prune back to a healthy side bud in early summer, but do not leave branch stubs.
A quick note:  When pruning coniferous trees avoid pruning the central leader, which will lead to multiple weak leaders. If you should lose you main leader you can replace it by gently pulling up a nearby lateral branch into a vertical position and secure it to the stub of the lost leader.

Topiary: The art of shaping trees and shrubs into fanciful shapes has been around since ancient times. To achieve some of the shapes wire cages are sometimes employed, but traditional topiary depends on patience and a steady hand. Not all shrubs lend themselves to this type of severe pruning. The best candidates are densely bushy, small-leaved (or needled) evergreens of slow to moderate growth. The favoured choices are: Boxwood (Buxus), Arborvitae (Thuja spp.), Holly (Ilex spp.) and Yew (Taxis spp). Privet (Ligustrum) is also commonly used but its fast growth requires frequent pruning.

Selective Pruning: Is the process of selecting individual branches to be pruned, rather than shearing non-selectively. The goal here is to prune for health and visual appeal while at the same time maintaining the shrubs natural shape. By following a pruning plan, and making well thought out cuts you will be able to greatly reduce the overall number of cuts required. Begin by removing all dead, broken, diseased or crossing limbs.  Cut them at the point of origin or back to a strong lateral branch or shoot. Often, removing this material opens the shrub sufficiently so that no further pruning is necessary. The next step is to make any corrective pruning cuts that may be required. These cuts may include pruning for size reduction, improving the shape, training branches to cover in bare spots, eliminating  weak or narrow crotches, removing a less desirable central leader where a double exists or pruning to increased air flow and sunlight to the center and lower portions of the shrub. Stand back once and a while to see how you are progressing.

Photo credit: photo/slide created by the author.

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