Photos by Steve Smith, VisionFire Studios
It seems like yesterday that the first hints of yellow from the forsythia bushes started to cheer up the garden and the hostas unfurled themselves after they made their welcomed return after a long winter sleep. But here we are saying good-bye to one of the strangest summers in recent history and questioning what the fall will bring. Well, with all of the uncertainty of those opened ended questions At Home wants to share with you some definitive answers about pruning and putting your garden to rest. It worked hard this year!
To find the answers At Home reached out to ISA Certified Arbourist Jeremy LeClair.
AH: Okay Jeremy, the question that everyone wants answered. When should we prune. Spring or fall?
Jeremy: First of all I want to say, my views are coming from an Arbourist point of view. Some gardeners may see things differently, but I stand firm on what I say.
What season depends on the objective of the pruning but this one goes to spring. Most routine pruning like removing dead or damaged branches can be done any time of year. Most recent studies have shown that trees actually rebound best from pruning during their most active growing periods, which would be spring. On the other hand, some fruit trees that are prone to fungal issues are best to hold off until the major wet period of spring is over.
AH: What trees and shrubs should be pruned in fall?
Jeremy: Mostly shade and street trees can be pruned at any time of year but when it comes to fall pruning it’s not so much about the species of plant to prune but more so the condition of it. With snow on its way, you may want to gear some pruning towards damage prevention. Wet snow and ice can break many branches so by tipping a few back to reduce larger sections from breaking may be a good approach. Russian sage, a small woody plant is one that we always tip back during our fall cleanups. They grow quite lanky and are very fragile so by cutting it back by half you can reduce the chances of larger sections breaking off. We do the same with butterfly bushes. Sometimes you may need to sacrifice some spring flowering by doing some fall pruning if there are some shrubs that are extremely out of control.
AH: Pruning forces new growth. When does it become too late to prune so plants can harden off in the winter?
Jeremy: Some types of pruning can promote a flush of growth. If your looking to tidy up some of your hedges and shrubs, then I would say you should be fine to clip off the stragglers right up to early October. If you’re practicing proper pruning on trees then you likely won’t be promoting a whole lot of new growth. Heading cuts, which is not recommended for trees are the types of cut that promote excessive growth. Choose your pruning methods wisely.
AH: Let’s talk perennials. What should be cut back in the fall or just leave to die off in the winter?
Jeremy: If you have time to cut back some plants then go for it. Hostas, lilies and peonies are all worth cleaning up but some folks will leave sedums, astilbe and hydrangea macrophylla up for winter interest. There are a few opinions on cutting ornamental grasses. We like to leave them up as some have nice structure and are a great winter garden display although they can be very messy depending on the location exposure.
If you have heavy-seeding perennials, you’ll need to decide whether or not you want them to spread. If your Brown-eyed Susans have started taking over the landscape, then make sure to dead head them in the fall to reduce the spreading. Now if you’re looking for that to happen, leave them or collect them and spread the seeds where you would like to see them take off.
AH: Tips for pruning popular shrubs?
Jeremy: Some may have different opinions, but my biggest recommendation would be to put down the shears and pick up a pair of hand pruners. There’s nothing wrong with shearing many shrubs but doing it over and over without any thinning will shade out all interior leaves and make the shrub harder to keep at the desired height. Boxwoods are definitely a plant that can handle a decent amount of shearing but I always hand prune out entire twigs evenly throughout the shrub. Allowing light to enter will keep some of the interior leaves allowing for more versatility in what you want the shrub to look like. Some shrubs require very little pruning. Rhododendron for example. Other than pruning out dead or broken branches you can pretty much leave it be, that’s if you have given it enough room to grow. If keeping it confined is required, always prune a branch back to a lateral to avoid unsightly stubs. Spireas come in many varieties. They can definitely be sheared for a compact manicured look but I prefer them loose and airy so going in to prune out older wood is my approach. The older stems usually are greyer in colour but have an obvious new shoot coming off of it. Beyond that new shoot is usually a section with spent flowers and dead; cut the branch off directly above the new shoot. This will really thin it out once you have gone through it but after a little tipping back, it will look just fine, especially for several years to come.
AH: What is the biggest mistake people make pruning in the fall?
Jeremy: Cutting back the flower buds resulting in a drastic decrease in spring flowering.
AH: Besides pruning, what fall work should be done in the garden before the snow flies?
Jeremy: I would say raking your leaves is definitely important. Other than keeping your garden tidy, it reduces the chance for leaves with disease or pest issues to re-appear next year. I use the word reduce because the odds that your neighbours didn’t take the same measures is possible and their leaves could easily contaminate your plants. Maple tar spot on Norway maples is an example.
Wrapping or caging your trees and shrubs are both common practice. Not only will it help to prevent damage such as sunscald, desiccation (drying out) and falling snow from roofs breaking branches but it will help reduce the amount of grazing from deer. We have noticed in the fall that the bucks tend to choose landscape plants to rub their antlers on rather then the thousands of trees in the surrounding woods.
If you have fragile plants in your garden that you would hate to step on once the snow blankets the ground, be sure to highlight it. Maybe it’s adding a tomato cage on it or placing a marker beside it.
AH: Is it ok to use branches and clippings from trees and shrubs for holiday décor?
Jeremy: Well that all depends on how much you harvest. Shrubs such as red osier dogwoods can handle a fair amount of cutting and actually will benefit from rejuvenation pruning in the spring to promote a new growth of vibrant red twigs. So clipping off a bunch before holidays should not harm it at all. Evergreens are a little different. Cutting off a bunch of pine bows on a small scale tree will only reduce its needle coverage and limit the amount of photosynthesizing it needs to operate. If you’re looking for pine, hemlock or fir bows, I would recommend supporting your local Christmas tree supplier or asking a friend with a woodlot if you can cut a bit. Most berries are ok to harvest but if it’s coming from your garden, remember to save some beauty for your winter landscape.
AH: Is planting in the fall ok?
Jeremy: It sure is. Spring would be my first choice as that gives the entire season to establish roots but there is nothing wrong with fall planting. Now fall is from September 22nd to December 21st this year sow when referring to fall I’m usually speaking about September and October. We have successfully planted later than that but why take a chance? If you are planning on putting a tree or shrub in the ground this fall just avoid wet areas. You will likely see that the frost may heave your plant partially out of the ground.
One last tip: Pruning trees is completely different than pruning shrubs. Shrubs can usually handle aggressive pruning year after year, however, with trees you need to be mindful of how much you take off. Each cut on a tree can have detrimental effects to its life and growth. Be purposeful when pruning trees or ask a professional for advice.