Brian Minter: Expert pruning tips for home gardeners

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One of the most confusing home-gardening activities can be when and how to prune our trees, shrubs and fruits. Proper pruning helps keep plants clean, free of disease and appropriately sized for the space in which they’re growing.

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We see so many cases where plants have been allowed to grow far too large for their location, and as a result, the beauty of the landscape is compromised. Larger trees can also pose a danger during extreme weather events, such as we have recently experienced.

Pruning isn’t just a winter activity; rather it’s a year-round job, keeping our plants healthy and optimizing fruit and flower production. With deciduous plants, the dormant season gives us the opportunity to observe a plant’s structure without the hindrance of leaves, allowing us to make better decisions about where to prune.

The key issue isn’t to be afraid to prune. It’s a learning process, and most trees are very forgiving. A number of excellent, how-to pruning books, with very helpful illustrations, are available, as well as online information. One site I appreciate is starkbros.com/growing-guide . Remember: There is more than one way to prune any type of tree, so don’t be intimidated. I like to be more philosophical in my approach. If you take the time to carefully look at any tree or shrub, noting its current condition and the way it’s growing, you will start to see how it needs to be pruned.

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Fruit trees are a good example of the advantages of winter pruning. This is a great time to cut out dead and diseased branches, as well as pruning to optimize fruit production and improve the shape of the trees. Apples, pears and plums have multiple stems and open branching. So, the ‘open vase’ method of pruning keeps the fruit production lower on the tree and easier to reach. Most apple trees sold for the home and garden market are semi-dwarf, usually on a M26 rootstalk, which gives the trees good strength. They will grow about 12 to 15 feet in height.

By pruning in an open vase form, the centre stems are cut out and the branches are trimmed to radiate outward. This method allows more sun and air to penetrate the tree; results in better fruit production and less disease in wet weather; and keeps the tree lower, especially when the branches are trained to grow in a more horizontal fashion. Almost all branches tend to grow upright. By simply weighing the branches down with small bags of sand or heavy soil, the branches can be trained to grow horizontally, which will prompt a far greater yield.

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Dwarf pears and semi-dwarf plums can be more difficult to find, but they’re all strong trees and should be pruned in an open vase form. Dwarf apples are available on various rootstalks, like M7, but as growers in the Okanagan do, they must be grown on support frames or wires because they don’t have the stem strength to be grown as stand-alone trees.

Sweet cherries are usually sold on a semi-dwarf Mazzard rootstalk, but they can still grow 15 feet or more. There are now some dwarfing varieties being grown on Gisela rootstalk that will stay in the 10-to-12-foot range. Because cherries grow with a strong central leader, we usually follow the principle of ‘central leader’ pruning. This technique simply means a yearly cutback of the main stem to encourage side-branching for better fruit production and to keep the tree more compact.

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In coastal areas with wet spring weather, peaches, nectarines and apricots need to be pruned so they can be fanned out or espaliered against a south or west wall of a home, garage or shed to capture the heat. If the building has a bit of an overhang to keep water off the foliage, it will help prevent peach leaf-curl fungus.

Peaches and nectarines grow very quickly, and a hard pruning now will help maintain their size and will ensure good fruit production this year. As a rule of thumb, cut back some of the aggressive branches about 25 to 30 per cent to control their size, and then cut out all the tiny side branches measuring less than 16 to 18 inches. The fruit-bearing, new growth from last year should be cut back by about 30 per cent. At this time, you can see the buds that will flower and fruit this year. Try not to leave too many as that will put stress on the tree. Apricots are slower-growing but can be pruned in a similar way.

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All small fruits need to be pruned back and cleaned up now. There are essentially three types: shrub forms, cane types and vining varieties. Everbearing raspberries, which produce fruit on new growth, can be pruned almost to the ground and still produce fruit in late summer. Main stem varieties should be trained over wires to produce their crops in late June through August.

Vining berries, like thornless blackberries, boysenberries, loganberries and tayberries, should be trained along fences or wire frames. I like to keep them trimmed quite severely each year, but to optimize production, I leave some old green growth stems, as well as new stems from last year.

Shrub forms of small fruits, like currants, gooseberries and jostaberries, need to have old wood thinned out to allow the development of new fruiting wood. At the same time, they should be pruned back to maintain a comfortable height.

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Blueberries don’t like to be pruned, but they need a thinning-out so more sun and air can penetrate the shrub for better production. You should now be able to see the flower buds on the plants.

Most flowering shrubs, like mophead hydrangeas, forsythias and flowering quince, already have their buds formed on last year’s growth and should be pruned only after they flower in spring. Flowering shrubs that flower on new growth, like weigelas, late blooming spiraeas and the cone-shaped peegee hydrangeas, can be pruned now. It’s important to keep this in mind so you can fully enjoy the blooms of all your flowering plants.

Pruning is so very important to the health, productivity and sizing of your garden. Depending on where you live in the province, now is a great time to begin pruning and tidying up your plants. Make sure you use quality, rightsized hand-pruners, loppers and pruning saws to do the job, and after pruning away any diseased wood, dip the blades in a disinfectant.