January can be cold, rainy and occasionally snowy here on the wet coast but don't let the weather stop you from working in the garden as there's plenty to do.
Significant work can be accomplished this month, including planting, transplanting, pruning, some construction projects, bed renovation and making hardwood cuttings. Working in the garden in January affords the opportunity to make disruptive changes at a time when presentation is not overly important.
Winter is a good season to prune shrubs, some trees and woody vines if you want to restructure those plants. When you prune plants during winter dormancy they respond by producing invigorated growth during the ensuing spring growth flush.
The advantage of invigoration pruning is the ability to rebuild plants such as forsythia, spirea, shrubby dogwoods, mock orange, weigelia, some viburnum and others. For those shrubs, prune to thin out the oldest, weakest or longest branches at ground level or close to the base of the crown. New growth will be produced from the ground or crown to rebuild the plant's structure.
Rebuilding plant structure in such a manner enhances health and flowering. Only shrubs that produce new shoots from the ground or basal portions of the plant's crown will respond properly to winter thinning.
For evergreen shrubs, like pieris, laurels, viburnum yews, junipers, boxwood and so on, winter pruning is done to restructure those plants into a new shape or lower, smaller size. This type of pruning does not involve shearing. Shearing uses a heading cut that induces bushiness and it's used for hedging and topiary only. Shearing of any shrub or tree that is not a hedge is a crime against nature and the act of an uninformed barbarian.
Restructuring evergreen shrubs is done by pruning (thinning) down to lower growths on the primary and secondary stems to redirect growth into the chosen buds or branches to develop the new form or size. Heading cuts are used in this process, but sparingly. For large, robust-growing evergreens, like cherry laurel, height can be reduced by onethird to half as long as cuts are made above healthy buds on the stem.
How far down you cut depends on the health of the plant. Weak plants respond to this procedure by dying. Healthy plants respond by regrowing new foliage in spring as a result of invigoration and redirection of energy. So choose your plant and cut carefully. I have reduced the size of large laurel hedges by five or six feet in width and height using this procedure, but only on healthy plants.
When it comes to winter pruning rhododendron and camellia, care must be taken to avoid cutting off the spring blooming buds or permanently damaging form. As a general rule, rhodos and camellia should never be sheared or pruned between June and March to reduce their height. Pruning during those months will remove flowering wood and the developing flower buds. If the plant in question is too tall then move it, lose it or let it grow tall. Shearing those plants into some kind of Chia Pet is ugly.
Larger-growing rhodos and camellias are often incorrectly pruned because they have been planted in a location that does not allow them to fully grow to mature size. In such cases a person should adjust the planting design and the owner's perception of size to facilitate a taller, layered and underplanted design. Height layering is a fundamental method of designing beautiful gardens. And transplanting and redesigning are long-term alternatives to pruning the same plant year after year.
January and February are also prime months to prune woody vines, such as wisteria, kiwi, grape, Boston ivy, Virginia creeper and honeysuckle. It's difficult to explain woody vine pruning without diagrams or field training. The general rule is to retain old wood while pruning back young wood. Old wood, for most woody vines, means two years or older wood, which is required to produce flowers and fruit. Young wood is not physically mature enough to reproduce (to flower or fruit).
Vine pruning in winter allows a good look at the leafless branching structure to help make pruning choices easier. Older, non-flowering wood can be cut out if needed, but be sure to leave a bud or two on the cut stem to regrow the flowering position in relation to the rest of the canopy. Vines, like wisteria, kiwi and honeysuckle, can often become unruly and overgrown and will benefit from pruning to restructure their old wood.
A few final words about winter pruning: Pruning during cold temperatures is acceptable but not lower than -1 or -2 C.
Pruning during freezing temperatures can cause branch splitting and cell damage. And use prudent precaution to prevent proliferation of disease by cleaning your pruning tools.
Todd Major is a journeyman horticulturist, garden designer and builder, teacher and organic advocate. [email protected]
