Garden Pruning
What is 'pruning'?
Pruning is not normally associated with herbaceous plants, as we often think of woody plants that we're shearing or shaping them. A U-shrub, for example, or a boxwood. But really, we do a lot of pruning with herbaceous plants. And when we pinch a plant, when we cut it back before or after flowering, when we deadhead or dead-leaf, those are all pruning techniques.
What variables are involved in pruning?
What to prune, when to prune and how to prune will vary from region to region. It will vary with the age of the plant, annual weather conditions, the soil fertility or moisture level, and just simply the gardener's objectives. Some years you might want a little neater look to a garden, another year you might want a delayed flowering for a special event, or to time it with an open garden tour, so it will just vary with your garden objectives.
How much pruning does a plant need?
That would depend on the type of plant, on the species and again what your objective is. Some plants, like certain Geranium, really require pruning after flowering to keep them looking good. With many of our spring flowering plants, a lot of people grow the moss phlox and that really should be sheared after flowering to keep it nice and full. So, again, it's very species specific on what we prune and when we prune.
Which plants don't respond to pruning before they flower?
Any plants that have a single stem, like cracosmias, delphinium, some of the foxgloves, don't respond as well to this pre-emptive pruning before flowering in an effort to delay bloom. This is because they have that single flowering stem that's unbranched. And so if we prune, we're basically removing that flowering stem.
What is 'deadheading'?
Deadheading is removing spent or dead flowers in an effort to prolong bloom or to cause a repeat later in the season of bloom.
How do I deadhead a plant?
Many times with flowering plants, particularly if they're branching, we look for a lateral leaf or a lateral flower bud. If they have a foliage at the base and they have single stems that come up from the base, we usually deadhead down into that foliage at the base, which we refer to as basil foliage.
What does it mean to 'cut back' a plant?
We cut back a plant either before flowering, to reduce the need for staking or to delay flowering, or we cut back after flowering to keep a plant nice and full to reduce that hole that sometimes will develop in the centre of many herbaceous perennials.
How do I cut back plants?
When we cut back either prior to flowering or even after flowering, we try to cut back above lateral leaves or lateral buds, and we want to keep the plant looking as natural as possible. Don't leave any bare stems without any leaves on them sticking up on top of the plant.
Why would I want to delay my plants from blooming?
How do I delay blooming in my garden?
We delay flowering on perennials by cutting back before flowering, and usually we're cutting back when the plants are anywhere from 16 – 24 inches in height. We can cut back by half. We can cut certain plants back like Flax, Heliopsis, Purple Coneflower, and the Echinacea; when they're in bud even. And we cut back then, at that time, we cut a little bit less off of the plant, and we usually cut back by about six inches when the plant is in bud.
