WHAT IS REJUVENATION PRUNING?
Rejuvenation pruning is the aggressive cutting of stocks (of certain shrubs) to the ground in late winter. There is a limited group of plants that consistently respond well to this type of pruning (I only have experience with the ones that I have worked on in The Boston area) Forsythia is one of the best.
REJUVENATION PRUNING A FORSYTHIA
BEFORE & AFTER
March 28 2022 - A large overgrown forsythia
June 27 2022 - three months later
On March 26, 2022, I did a partial rejuvenation pruning to a large, old and tired forsythia. I cut some large older stocks on the back side of this plant to the ground. Because this is a very visible location, the client was concerned about losing the screen and how the plant would look in the short term. So, instead of cutting the entire plant to the ground, we did partial pruning.
If you are going to take the partial approach start by cutting down the larger older stocks. By taking this strategic approach you can preserve most of the plant while cutting down portions of the older wood over the course of a few years. In most instances, if you do this to the right species in late winter you can cut the entire plant to stubs 3 inches above the ground and it will grow back with a younger healthier appearance. However, you need to set your client’s expectations.
Even though I have done this for a long time; every time I cut plants completely to the ground, I offer this disclaimer “if the operation is a success, you can visit the patient if not you can claim the body”.
That’s my corny way of saying if a couple of plants die don’t be surprised. This very rarely happens but it can happen. There have been a few instances of cutting down entire privet hedge rows when a plant or two was lost. The second thing your client needs to know is. it will take a few years for the plant to grow back to its previous size.
So, if that is going to be a problem take the partial approach over a few years. Usually, these types of plants grow back over the course of a few seasons and as the term rejuvenate suggests you replace your old tired shrubs with younger vibrant shrubs. And it’s a lot less money than replanting.
Large older stocks cut to the ground in March to encourage sprouting from these wounds and from the ground
The new green stems that have reacted to the wounding and grown 3 feet – June 27 2022
WHAT YOU NEED TO KNOW ABOUT REJUVENATION PRUNING
If you decide to experiment with this type of pruning you need to know three important things; what shrubs will respond well to this aggressive pruning, the condition of the plant and whether to do it in March or April.
If you do this to the wrong plant you will either disfigure or kill it. If you do this to a plant that is weak or almost dead…guess what? If you do this in the fall, summer, or early winter even to the right species you can do more harm than good.
The last thing to consider is if you want the best results to fertilize the plant in late fall (October 15 to December 1) depending on the weather that year) before you prune. I prefer a balanced liquid tree fertilizer with 5- 10% nitrogen. If the soil temperature is above 45 degrees the plants will still be actively absorbing nutrients. With the fertilizer actively working in the plants before the pruning it adds an additional boost that really make a difference.
As you can see there was no growth at the base of the plant in March. This newer growth not only rejuvenates the plant by creating younger more dynamic stems it also improves the plant’s ability to provide screen.
September 5 2022 The new sprouts have grown three feet
DECIDING HOW TO PRUNE
Rejuvenation or basal pruning is a great tool to have in the pruning toolbox. Just remember the Decision Pruning Guide matrix before you prune anything.
Species: know your plants and how they will respond (always the hardest one)
Timing: what time of year?
Condition: if I prune this plant, am I doing more harm than good?
Expectations: how long will it take to respond? Will my client be upset if it looks bad, lose screen, and takes a long time to grow back?
Follow up: will there be more work I need to commit to doing in the future because every plant will have a reaction to pruning?