Pruning conifers, broadleaved evergreens and flowering shrubs
There is no putting it off any longer. When we have the odd nice day, you really must start getting your trees and shrubs back into shape before the dormant season ends, usually in late February. Pruning extends the health and life of all the trees in your garden, enhances their beauty and prevents them from crowding out other plants.
Let's start with evergreen conifers. Junipers are probably the biggest problem when it comes to keeping shrubs in check. Whether they are low- or medium-spreading types, or an upright variety, they need to be pruned at least yearly to enhance their appearance and to keep them from taking over.
With electric hedge trimmers or two-handled grass shears in hand, simply trim back into last year's growth while shaping the plant. Low-spreading varieties usually look best in a fan shape, while uprights can vary depending upon their form, but I have found the narrower you prune them, the better they look. If they get ahead of you, you may have to be a little more severe. Remember if you prune back into the old hard wood, it takes a long time for your junipers to look good again.
There are, however, a couple of exceptions to take note of. Whether they are compact ornamentals or tall specimens, all pine and spruce trees are best pruned in May. The reason is that they grow by producing buds, or candles, which should be allowed to "pop" before pruning. If you cut the buds or candles off, it may be a whole year before any growth appears, leaving a rather chopped appearance.
Prune pines in May when the new candles are shooting up profusely. When this new growth is pruned, conforming to the shape of the tree of course, a multitude of new buds will develop, ensuring much slower, bushier growth. You can even cut back into older wood at this time and still get bud development for next season. The pruned-back candles will still develop this season, leaving a much more attractive tree.
The same is true of spruce trees. Let the new buds pop first, then prune following the shape of the tree. Although many new growth tips will be cut off, others back further on the branches will develop nicely to fill in the tree. Try to maintain a rather narrow form on all your spruce trees, especially blue spruce, to keep them looking handsome without overpowering the landscape.
Many broadleaved evergreens can be pruned back now as well. Laurels, Photinia fraseri, summer-blooming heather, boxwood, euonymus and many others should be cut back fairly hard to maintain their shape and prevent them from becoming too big for their location. A mid-summer pruning may also be necessary for very fast-growing broadleaved evergreens. Pieris japonicas, azaleas, camellias and rhododendrons should only be trimmed just as their flowers finish in April or May.
Most flowering shrubs should not be pruned now for fear of cutting off this year’s flowers. As a rule of thumb, prune most varieties immediately after they flower. Mophead hydrangeas, lilacs and forsythias are classic examples. Weigelas, deutzia, potentillas and a few other flowering shrubs bloom on new growth and can certainly be pruned now.
When you prune flowering shrubs back immediately after blooming, keep two things in mind. First, try to keep them compact because they so quickly overpower a garden. Many new, more dwarf varieties are solving this problem. Second, try to renew the plant by taking out the old hard wood, leaving the more recent growth from the past two years to give you good colour.
This summer's growth on forsythia, for example, will not be as spectacular as last year's wood. Chinese witch hazels also bloom best on old wood. It is also a good idea to thin out shrubs, leaving lots of room for air and sunshine to circulate and penetrate. Look at the shape of the shrub before you prune, and try to maintain or improve that shape.
Flowering trees, too, should be pruned after you have enjoyed their blossoms. I follow three simple rules: first, cut out any diseased or damaged branches; second, cut out all the thin and wispy branches that grow toward the centre and clutter up the tree; third, cut back the ends of the major branches to check the growth. Always try to maintain the integral shape of the tree when pruning. Having someone on the ground directing where to make the cuts is a big help.
Roses should not be pruned until after the last hard frost in March.
Even though at the end of February last year we had a severe cold spell, it’s still all right to prune these plants now. It takes a little work, but pruning is actually interesting and more enjoyable than you think. You have to be a bit of an artist, and you get to judge your work next season when the blooms appear.
Brian Minter is a master gardener who operates Minter Gardens in Chilliwack.