LONGER days, signs of spring in the garden and the end of February mark the end of the dormant season's pruning cycle.
Dormant season pruning has been used for centuries to reconstruct, renovate and develop structure in woody shrubs and vines.
Contrary to popular myth, winter pruning is not done because you can see the tree's branch structure; the primary advantage of winter pruning is to use plant growth response to achieve invigoration and restructuring of plants.
By the end of February fruit trees should have already been pruned to remove dead, diseased and damaged stems while retaining all branches and fruiting spurs that will produce flower and fruit this coming season. If you haven't already pruned your fruit trees, better get it done soon before the sap starts rising up the stems and flushing out new growth.
Remember to be gentle when pruning fruit trees. Hard pruning that cuts back too far on the branch or removes too much volume of wood will result in a misshapen tree that bears no fruit. Always retain a balance of mature branching and newer branching and avoid pruning off more than a quarter to one third of the tree's total volume of branching.
Late February is also a great time to reconstruct or renovate hedges to lower their height, width or redevelop a more dense appearance. Hedge renovation involves pruning back all branches on the plant by one third or half of their total length to redevelop a smaller and denser hedge. It may take two or three years to fully recover but the results and increase in yard space are worth the wait.
Hedge renovation works on laurels, yew, photinia, pieris, Portuguese laurel, some native cedars but not all and a few other hedge species. Renovation does not work on pyramidalis hedges, cypress, many older cedars, pine, hemlock and any plant species that does not possess adventitious buds on their stems or hedges in poor health.
Laurel hedges that have become real estate eating monsters respond particularly well to renovation during the dormant season. With any hedge that you wish to renovate be sure when you prune back on older branches to look for leaf scars where a dormant bud will be, or look for small bumps on the stems indicating adventitious buds that will regrow and cut there.
There are also many deciduous shrubs like forsythia, winter viburnum, deutzia, shrubby cinquefoil (Potentilla species), quince, spirea, philedelphus, weigelia and beautybush (Kolkwitzia species) to name a few that benefit from winter pruning. With all of those shrubs pruning is done to develop replacement growth from the base of the plant that will rebuild structure.
When doing this sort of pruning choose the oldest, weakest or most misplaced stems and cut them right to the ground which will force new growth from the base of the plant. On very old plants you may need to prune slightly above the ground leaving one or two inches of stem to regrow a new branch. When doing this type of basal thinning try to select branches according to what I have mentioned with the goal of developing uniform density across the plant's crown which promotes healthy regrowth and beauty.
For shrubs that are primarily grown for their beautiful stems like the red or yellow stemmed dogwoods (Cornus species) the goal of winter pruning those shrubs is to use invigoration to develop strong, colourful stems that show their colour virtue to best effect. As shrubby dogwoods age, their stems lose some of their bright red or yellow colouring and the more the stems are sheared at the top of the plant, the fewer colours there are in the stems. To renovate those shrubs cut off all stems, and I mean every single stem, down to two or three inches above the soil cutting a quarter inch or so above the chosen bud on the stem. Always prune to produce a straight cut, no sloping dagger cuts please.
The resulting growth in the coming season will be vertical, colourful and beautiful.
It's still a bit early on the North Shore to prune hydrangea, roses and sub-shrubs like rosemary, lavender and so forth. However, this year's winter has been quite mild so everyone needs to gauge the weather for their specific elevation and locale.
The end of February also marks the near end of the winter mulching season. Mulching during winter is recommended because you can access planting beds without damaging lush new spring growth and lay down a life giving protective layer of organic matter that will enhance soil fertility and prevent weed growth.
Spring is just about here so get out and finish those last pruning and mulching jobs so you can enjoy the garden in spring without disturbance.
Todd Major is a journeyman horticulturist and chief horticulture instructor at the University of British Columbia Botanical Garden. For advice contact him at [email protected].
