Fall Pruning

 

Photo by Karen Knuepfer

***Fall Pruning…Simple, right?

An article by York County Master Gardener Karen Knuepfer, posted October 2021

(Put here to find it later😊)

Ahhhh, September…

There is something about the cooler temperatures, the crisper mornings, the generally softer air and bluer skies that just promises the delights of Fall. And, gets many the gardener itching to put away the summer garden and prepare his/her grounds for the next growing season. Let the Great Clean-Up commence! For many, that includes grabbing the pruning shears to…Tidy Up.

WHOA, Nellie, or Ned! Not so fast! While it may “make sense” to clean up the whole darned mess, in most cases, September/October is NOT the time to prune. To prune is to stimulate new growth. Fall is when plants in our region are actually trying to go dormant, to enter a state of temporary metabolic inactivity or very limited activity, basically suspended animation, during which plants conserve energy and protect themselves from the rigors of Winter’s frigid temperatures and conditions. Plants know when to hunker down and save their reserves. If pruning encourages new growth just when a plant is slowing down, that new growth may be doomed; the plant will certainly be stressed and thereby weakened just when that new growth does not have time to harden off before the first frost.

So, Nellie or Ned…take a deep breath and put away the pruning shears for at least a couple of months. Use your gardener energy to rake up dead leaves, [Do you need to rake up leaves?] mulch your beds (using those dead leaves!), commit those dead annuals and vegetables to the compost heap. That being said, certainly this is the time to inspect for and remove dead or dying diseased plants (blackened stems, withered leaves, spotted foliage may be indicators); cutting back with the pruners may be appropriate in this case and trash or burn the removed plants rather than composting. No sense incubating a disease. Prune back or cut down dead limbs or branches, too. No sense in risking injury or damage due to flying debris in a Winter wind.

Actually, the better time for true pruning is during that Thanksgiving-to-New Year period of Winter or Early Spring. Certainly some time after several hard frosts is optimal. Pruning creates a wound that the plant must seal; pruning before the plant’s natural spring growth spurt will allow the wound to seal and heal faster. Choose clear, dry days to work. Cool temperatures provide less stress to a pruned plant and dry conditions reduce the growth of microbes that can lead to disease which may undo the benefits of your hard work. Focus on removing dead or dying branches, crossing branches which may rub (cut the smaller branch off), and vertical growth or suckers (cut as close to the base of the growth as possible). The general benefit of good pruning is to provide more air circulation and light throughout the plant, yielding more flowers and fruit for flowering plants, shrubs and fruit trees, and healthier canopy for non-bloomers.

Other thoughts regarding To Prune or Not to Prune:

Crape myrtle with seed pods reaches to the sky.

Many perennials and native plants (think yarrow, cone flower and agastache) and ornamental grasses are gorgeous in the Winter, even in their dry, dormant states. They provide textural interest in the Winter garden, as well as shelter and food for birds, insects and other wildlife. Mums can “come back” for years if left unpruned until Spring so their their roots are protected from the harsh Winter temperatures; and you will know where they are in your garden after the snows melt!

If you just have to get out and wield those pruning tools, be sure to wait until we’ve had a few hard frosts. This allows your perennials, for instance, to go fully dormant. Cut your plants back to 3” above the ground. Look for signs of disease and get rid of those sickly guys. Burn or discard what you remove. Your perennial beds will thank you in the Spring and Summer.

Shrubs are best pruned in late Winter or early Spring if they are non-blooming. The general rule of thumb for flowering shrubs is to prune immediately after blooming (think Azalea, Spirea). But it is important to know the difference between Spring bloomers that set their buds on old growth, such as oakleaf hydrangea: prune after blooming, and those that wait to set their buds on new growth, such as Annabelle or PG hydrangea: OK to prune in Winter. I admit, it can get confusing!

Deciduous shade trees like the oaks and lindens we have around York are best pruned in Winter. Their branching structure is easy to see without their crowns of leaves, so beneficial pruning will be more effective and confident. Some other shade trees like maples, birch and dogwood will produce a heavy flow of sap if pruned in the Winter – unsightly but not harmful. Nevertheless, you might want to wait until Summer when their leaves are fully expanded to shape up these “bleeders.”

[Cornell information sheet on pruning techniques and timing.]

Broadleaf evergreens like holly and magnolia generally need no pruning at all, while needleleaf evergreens, for instance, such as yews, junipers and firs are best pruned early in the growing season; take care not to cut back into the old bare wood which may not sprout new growth. Pine trees are best pruned during their “candle stage” growth spurt, but prune very gently, taking no more than half the “candle.”

Deciduous fruit trees, say apples, cherries and plums, are a whole other matter. Despite being Spring bloomers, selective pruning is best done mid-Winter. You will lose some flower buds but you will provide a more open growing environment, producing a better fruit crop.

When I chose to write about this simple topic: Pruning in the Fall, I truly had no idea how complex a subject I was taking on. Suffice it to say, you need to know your plants and need to proceed with some education and caution to be a happy and successful Pruner. Best practice: know your plants; use clean, sharp tools; be mindful of the calendar and the weather; and leave pruning in high places and near power lines to the professionals! If you are not sure what to do, check in with your local Extension office or the Master Gardener Hotline 717-840-7408; yorkmg@psu.edu; 2401 Pleasant Valley Road, #101, York PA 17402. And, know that the Fall Garden Clean-Up will probably be more than a one-weekend project.

Happy Fall, ya’ll!

(Photo by Karen Knuepfer)

Karen Knuepfer is a Master Gardener in York County. Penn State Master Gardeners are volunteers for Penn State Cooperative Extension.