The Natural Prune

Pruning season is in full effect now. It’s a fun time of year because as early-blooming shrubs come out of bloom, it is generally the perfect time to prune them before they begin setting flower buds for next year.

Pruning can be a daunting task for many gardeners who are often incapacitated by the thought of timing things properly and the fear of killing their plants. Rest assured, if you time your pruning immediately after the flowering period, and remove no more than one third of the plant, your plant should be fine and flower again next season. (I said *should* because there are always exceptions, and if the plant is stressed in other ways such as through drought or nutrient deficiencies, the ability of the plant to rebound from pruning can be compromised. Additionally, some plants are more tolerant of a ‘haircut’ than others.)

I think that in reality, the main concern when it come to pruning should be disfiguring a plant- which happens all too often. Plants, like people, come in all shapes and sizes; and, also like people, the natural growth habit of a plant is what contributes to it’s natural beauty. This is why it drives me CRAZY when I see hedge shears used as a general all-purpose pruning tool (especially by landscape crews).

Don’t get me wrong- I love my hedge shears BUT they serve a specific purpose and that is for pruning hedges.

Hedge shears should only be used for one thing and that thing is….

anyone…

anyone…

Bueller?

The answer is HEDGES!!!!

Hedge shears are great for pruning things into lines, tight globes, pyramids, random animal shapes… but when it comes to flowering shrubs, they absolutely decimate the natural growth habit of a plant. (If you are a person who likes all the plants in your garden to be rounded- you are not alone, many people do, however this is not the post for you! You may now save yourself a few minutes of time and gracefully bow out of this article.)

Hedge shears: great for things like boxwood spheres… but not for the other flowering shrubs in the garden (such as the Hydrangea paniculata or Cornus kousa growing in the background).

OK- back to natural shapes…

Let’s use a kousa dogwood (Cornus kousa) as an example. This is a shrub known for it’s architecturally stunning horizontal branching structure. Here are two photos- the first on the left showing the natural form of the tree, and the second (on the right) that has fallen victim to the hedge shears.

Poor dogwood! This type of disfigurement is completely avoidable with a little knowledge of how trees and shrubs grow and respond to pruning.

The Effect of Pruning

Let’s backtrack just for a second and take a look at what pruning actually does to a plant. When a pruning cut is made, it encourages the plant to grow from the next available growing point behind the pruning cut which is either:

1. A bud or set of buds

2. Existing branches

If a branch has been pruned back to a bud/buds, this is known as a ‘heading-back’ cut. The bud(s) are essentially forced to grow (in the direction in which they are pointing) and the pruning has ultimately promoted branching at the point of pruning.

Pruning back to a bud (a ‘heading back’ cut). The yellow dot indicates the pruning point and the red arrows illustrate the direction of resultant growth.

When a plant is routinely sheared (or just the tips of branches are snipped off to control size), the constant growth from buds and resultant new branches ultimately leads to a tree or shrub with really dense growth and branching on the outer edges and bare stems within the centre of the plant- not exactly a natural form!

A basic schematic that shows how routine shearing leads to a shrub with very dense branching on the outer edges of the shrub and a sparse interior.

On the contrary, when a branch is pruned back to another branch (known as a ‘thinning cut’), the plant will essentially direct it’s growth toward that remaining branch.

A ‘thinning cut’ back to a lateral branch (indicated by the yellow dot) and the resultant growth directed toward the remaining branch (as indicated by the red arrow).

It is these thinning cuts that are the key to what I like to call ‘the natural prune’. Here is how it is done…

The trick is to visualize a ‘shrub within the shrub’. Usually I get blank looks when I use this line- but it is the best way to describe the process. Essentially, you want the shrub to have the exact same branching structure after the pruning job is complete as it did before you took the secateurs to it, yet the overall size is scaled back.

Perhaps the idea of pruning sounds even more daunting than before? Have no fear! Let’s walk through this together.

I generally follow three steps when doing a ‘natural prune’ on trees and shrubs:

1. Identify a long branch

2. Trace this branch back to where it connects with a secondary (lateral) branch somewhere within the shrub

3. Prune the long branch close to it’s union with the lateral branch (usually a few millimeters away from the point of connection, with the pruning cut angled up toward the lateral branch)

4. Continue this technique around the whole shrub, multiple rounds if necessary, to remove all the longest branches

An overly simplified image of a shrub illustrating the use of ‘thinning cuts’ to reduce the overall size. The coral-coloured branches indicate the portions of the shrub to be removed, the rest of the shrub remains. Note that the overall height and size of the shrub has been reduced using this technique.

Using this technique:

• with the longest branches removed, the shorter ones become the outermost branches and therefore the overall size of the plant has been reduced

• the pruning cuts are hidden within the shrub so you won’t be looking at little stubs that scream “I’ve just been pruned!”

• the form of the shorter branches remain untouched and therefore the natural form of the shrub remains in tact

• The plant won’t be forced to branch out from buds along the pruned stem because, by pruning to a secondary branch, the tree/shrub has essentially been told to direct it’s energy toward growing that secondary branch

Simple!

A sprawling ‘Glow Girl’ birch leaf spirea (Spirea betulifolia ‘Tor Gold’) immediately after flowering (left) and after a natural prune (right).

A dwarf Korean lilac (Syringa meyerii pallibin) kept as a globe. In this case hedge shears could have been used, but I reduced the size by thinning the longest branches.

Some Final Thoughts

This type of pruning is subtle- something that can be done yearly or every other year to help limit the size increase of the shrub over time. Doing subtle routine pruning is a much better approach to size control than trying to reign in a plant that is on the verge of outgrowing it’s garden space (which is usually the time when people begin to think about taking action). Drastic pruning on an overgrown plant is not only hard on the plant, it rarely looks natural and is usually a loosing battle. With all that said, overgrown plants are best avoided by ensuring your garden can accommodate the mature size of any tree and shrub that is planted in it.

So have fun and take your time with this pruning technique. It will take much longer than a ‘hedge shear haircut’, but the extra time will pay off when you are sitting in your garden admiring the diversity in forms throughout your yard.

Rain Dance

It’s hot. Really hot and dry too. Unless of course you have been hit with the torrential rains that tend to go hand-in-hand with the pop-up thunderstorms spawned by this weather. In any case, these driving rains are better at washing away a garden rather than watering it! So the issue of dryness remains…

In my garden, the latest heat wave is beginning to take it’s toll on my plants. Thirsty mature trees slurp up the moisture from the lowly ‘riff raff’ below (i.e. my perennials!) and the sun makes short work of baking other areas of the yard. We have reached the point on our property where supplemental irrigation is necessary.

Oh how we could really use some rain right now! (Photo credit: Pete Nowicki on Unsplash)

Now I should start by saying that gardens need water- but it is the quality of the watering that counts as opposed to the number of times the garden is watered on a weekly basis. In general, a mature garden (as opposed to one that has been recently planted) needs about an inch of water a week. Sure, some plants are thirstier than others (and these plants often display their displeasure for the dry conditions with a little wilting tantrum) but this ‘inch a week’ guideline is one to keep in the back of the mind throughout the growing season- even if it is a very general guideline.

So with this in mind, here are some tips to effectively water a garden:

• Water in the morning. Grab that morning coffee and enjoy the zen that watering a garden can bring. Morning irrigation sessions allow the foliage of the plants to dry out as the day progresses. Many plant diseases require moisture to spread and/or to successfully infect a plant. Reducing the ‘leaf wetness period’ can go a long way in reducing the incidence of disease. Watering in the morning also conserves water- less water will be lost to evaporation (which is a problem when watering midday- the hottest part of the day).

• Use the ‘shower’ setting on your hand-held sprayer for watering garden plants (the ‘soaker’ setting is great for planters). I find these settings create the least amount of mist (mist just gets lost to the air and is ultimately a waste of precious water). Keep this point in mind when choosing a sprinkler setting too.

• One deep watering is far better than many shallow waterings. This strategy encourages deep rooting and ensures that ample moisture has been provided to the plants (rather than chronically underwatering them)

• Water around perennials and small shrubs and don’t forget to water out to the drip line of larger plants (The drip line is the point on the ground to which the farthest reaching branches of the tree/shrub extend. It is out near the drip line where a large proportion of the feeder roots of trees exist and these are the key to taking up moisture.)

• Water the ground not the leaves- afterall, it is the roots that take up the water. This is not possible with a regular sprinkler but if hand watering, you have control over this- exercise that power!

• Do not water flowers…unless you like blemishes; water droplets resting on some flowers can magnify the sun and cause brown blemishes on the petals as a result. This is not a given, but it is certainly a consideration.

• Keep a keen eye on planters. As you’ve likely already noticed- pots dry out fast! The smaller the planter, the quicker it dries out. Additionally, porous planters (such as coco fibre lined baskets, fibre pots or terra cotta) also dry out quicker than non porous ones such as ceramic, fibreglass or plastic. Check on pots throughout the day- they will normally require daily watering, but on really hot days or windy days (when the air essentially sucks the moisture out of the plants and, in turn out of the soil), they could require more than one watering.

Pots lined with materials such as coco fibre dry out quickly; it is not unusual for them to require two waterings a day!

• Water in stages, especially if a planter or part of the garden has dried out. If the soil is dry, it takes time to absorb the water (in a garden, you will often see most of the initial water running off extremely dry soil). To avoid wasting water and ensure the soil is actually absorbing the moisture, water an area or pot briefly, move on to another location/pot, followed by another; rotate through your planters or garden until the plants have received a good soaking.

Final note: At the time of writing this, we were in the midst of a dry spell and heat wave. The forecast calls for the heat and humidity to break today with the arrival of a cold front. (Phew!) Looks like I am saved from some watering chores for now. Instead, I will do a rain dance!