A question we hear a lot is “When do I prune this, fall or spring? Is one better than the other?” and well, there are a lot of answers. Most plants do best if you leave the pruning shears alone and wait until late-winter/early spring (late February through mid-April, with March being most ideal in Iowa). But, like with anything, there are a few exceptions to this rule. I asked Dustin, our nursery manager, and Kelly, our head arborist (and star of Homesteading Hints!) what their answer is to this common question.
Renewal Pruning vs. Hard Pruning
First and foremost, it’s important to know the difference between renewal pruning and hard pruning. Hard pruning is when you do a more severe cut-back and encourage vigorous growth. A hard pruning is usually done when a shrub has become leggy and overgrown or you aren’t seeing blooms year after year. In this blog, we’re mostly talking about renewal, or light pruning – cutting back a little bit each season to keep the plants shape after a growing season and promote new, healthy growth for the next.
Fall Pruning: What to Cut and Why
A good starting point when considering what to prune in the fall is referring to the Three D’s. We recommend you cut back anything that is dead, damaged or diseased. Remember not to compost any diseased material, you’ll want to dispose of this far from your garden so any illness is not reintroduced. This is also a good time to evaluate any potentially dangerous limbs as we move into winter. You should have a professional cut that branch hanging over the house before it has the added weight of ice and snow to bear.
One plant you really want to prune as soon as they die off in the fall is peonies, with the exception of tree peonies – which you really don’t need to prune at all. Peonies should be cut back to the crown each fall to prevent disease and insect infestations.
Fall Pruning: Why You Should Resist The Urge
More times than not, we recommend not pruning in the fall for a variety of reasons.
- Fall pruning can stimulate new growth as we move into the cold season and cause damage to your plants.
- Grasses, perennials and shrubs provide invaluable shelter to the wildlife in our area.
- You run the risk of sacrificing next spring’s blooms if you prune a shrub that flowers on old wood.
- Plants with seed heads provide a food source through the winter. Don’t prune plants like coneflowers, black-eyed susan, ornamental grasses, sedum and joe pye weed for the birds, insects and various other wildlife. (They also look pretty in the snow)
- Open wounds make plants susceptible to disease as pests seek shelter from the rapidly cooling temperatures.
- Leaving ornamental grasses and dried flower stalks provides winter interest in your garden and keeps it from looking so empty and dreary.
- Anything that you are on the fence about it surviving until spring will do better left alone.
Spring Pruning: Why It’s What We Recommend
We call it spring pruning, but it’s really more of a late winter pruning that we recommend. In central Iowa, mid-to-late February through early-to-mid April is best and we say the sooner the better. You never know what Iowa’s spring will bring. It’s most important that your fruit trees and deciduous plants are still dormant when you take the shears out. Plants we recommend pruning early spring include Rose of Sharon, Knockout & Tea roses, Dogwood, Ninebark and Boxwood.
Shrub roses respond well to yearly renewal pruning. Each year cut back about ⅓ of the branches throughout the shrub to the ground, leaving the other ⅔. Start with the oldest branches, and each spring remove a different third. You will be rewarded with new, vigorous growth and lush blooms.
Boxwoods should be pruned in the spring to clean them up and define their shape for the season. Additional touch ups can be done through mid-summer if you have some stray branches.
While you can technically prune your Rose of Sharon at almost any time, we think spring is best if you’re really wanting to encourage a flush of new blooms. This is because Rose of Sharon blooms on new wood. The only time you don’t want to prune this beautiful shrub is late spring, when buds have developed but not yet bloomed. If you really want to shape your Rose of Sharon, give it a prune in the winter when there are no leaves. If you want to prevent seeds from spreading, prune in the fall after they finish blooming and you see the seed pods forming.
What About Summer?
Early spring- and summer-flowering shrubs should be pruned immediately once they’ve finished blooming. This way you are sure to avoid removing any of next season’s best blooms, which you’re likely to do if you prune in the spring. Plants that fall into this category include lilacs, magnolia, forsythia, and weigela. If your spring-flowering shrubs are healthy and not overgrown, they should only need a light pruning. Mid-season pruning can be used to tidy up the garden and will sometimes reward you a second round of blooms.
When It Comes Down To It…
It’s really up to you when you prune a lot of things. If you don’t like the way your ornamental grass looks after a couple snows, prune them on a sunny day this winter. If you have no interest in gardening in the cold, get it done during the pleasant days of autumn. It’s still best to wait until the plants have gone dormant for the season, but we often have pleasantly warm days intermixed with the drops in temperature. Sometimes, a plant in your garden just needs a hard refresh and you’re willing to sacrifice the blooms for a year. Do it. You’ll be rewarded down the line.
No Matter The Season, Safety Comes First
For many perennials in your garden, a lot of safety equipment won’t be needed. You always want to wear gardening gloves, long pants and long sleeves. Safety glasses are also recommended. When pruning trees and anything else above your head, you should include a hard hat and steel-toed shoes in that list. Using the right tools for the job is key as well. Also keep in mind your experience and your limits. Call in the professionals if pruning requires a ladder, access is difficult or you’re anywhere near a power line.
Specific Pruning Questions?
Ask before you cut! Give us a call today at 515.981.1075, we’re always happy to help! Or send us an email, find us on Facebook or Instagram or visit us in person at Ted Lare Garden Center. It’s our goal to help you feel confident in your garden and keep it looking its absolute best.