The short answer to this is no! You should not use pruning paint to seal pruned limbs at all. They are better left to undergo natural healing through their own plant defense mechanisms.
Why Painting on Tree Pruning Sealer Is a Bad Idea
For a long time, it was common practice to use a pruning sealer like tree tar when trimming trees — a seemingly common-sense practice recommended by trained arborists and nursery workers alike. Today, homeowners are learning why painting on tree pruning sealer is a bad idea.
Generations of homeowners grew up believing that painting on an application of pruning sealant on tree limbs/branches was an integral part of “safe” tree pruning. No longer. “Current best practices no longer recommend applying sealants [pruning spray or pruning paste] to tree wounds,” says Karl Flocke, a woodland ecologist who works for the Texas A&M Forest Service.
So let’s talk about why it’s now considered a gardening myth and how yesterday’s tree bandage became today’s bad practice.
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In this article:
- What is a Tree Pruning Sealer?
- Why Tree Sealant Isn’t Necessary
- Tree Sealant Impact on Human Health
- Should You Seal Pruned Limbs at All?
- The Exception: Oak Trees
- How to Remove Pruning Sealer
- FAQ
What is a Tree Pruning Sealer?
A tree pruning sealer is a specially designed waterproof product that is applied via aerosol spray or painted on with a brush. It is used for the exposed cut on a limb or tree branch after pruning. For many, many years — and still to this day in some cases — people were told by an arborist that tree wounds had to be covered with a sealant.
A tree pruning sealant is a bandage of sorts meant to cover the wound. How does this “bandage” help a tree to heal? The packaging makes a few claims:
- Aids in the healing of pruning cuts
- Minimizes sap loss
- Protects trees from decay, insects, and fungi
It was an easy DIY project, and the product was (and still is) in stock at all garden and big box stores, so it became ingrained as a habit for homeowners.
While good in theory, scientific research conducted by Alex Shigo of the U.S. Forest Service in the late 1970s explained that pruning cuts should not be painted. Rather, the tree should be left to heal through its own devices after you prune it.
He emphasized the importance of following proper pruning practices. Let a fresh cut heal naturally instead of covering it with a wound sealer, he urged.
Painting wound with wound paint or dressing can:
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- Prevent the tree from forming calloused wood, which can keep the tree weaker.
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- Seal in water, bacteria, fungi, and decay.
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- Attract disease causing organisms that feed on the wound paint.
- Interfere with a natural recovery process that nature has taken eons to perfect!
To help keep your trees healthy when pruning:
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- Prune in late winter while trees are dormant.
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- Sterilize pruning shears and saws between cuts with rubbing alcohol or hydrogen peroxide.
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- Target specific risks by treating wounds with an organic fungicide or insecticide.
- Make careful, clean pruning cuts just outside the branch collar, where the tree can most quickly heal.
There are a few devastating diseases, such as oak wilt, that are introduced through insects feeding off pruning cuts, then spread from tree to tree via the roots. Wound paint can reduce (but not eliminate) the risk of these infections, so some tree experts feel that the downside of wound paint is better than the risk of spreading this disease throughout a neighborhood.
Check to see if diseases are a problem in your area. If they are, follow the guidelines from your local extension service regarding the use of wound paint when pruning. In general, however, only use wound paint when absolutely necessary to prevent specific diseases.
Further Information
- The Myth of Wound Dressings (Washington State University)
- Should I Paint or Otherwise Treat Pruning Cuts? (extension.org)
- Wound Dressings (Shigo and Shortle, Journal of Arboriculture, 1983)
- Proper Pruning to Prevent Oak Wilt Infection (Texas Forest Service)
- When to Trim Trees and Shrubs
Editorial Contributors
Danny Lipford is a home improvement expert and television personality who started his remodeling business, Lipford Construction, at the age of 21 in Mobile, Alabama. He gained national recognition as the host of the nationally syndicated television show, Today’s Homeowner with Danny Lipford, which started as a small cable show in Mobile. Danny’s expertise in home improvement has also led him to be a contributor to popular magazines and websites and the go-to source for advice on everything related to the home. He has made over 200 national television appearances and served as the home improvement expert for CBS’s The Early Show and The Weather Channel for over a decade. Danny is also the founder of 3 Echoes Content Studio, TodaysHomeowner.com, and Checking In With Chelsea, a décor and lifestyle blog.
What Is A Pruning Sealer?
Pruning sealers, also called pruning paint, are products that claim to “aid the healing of pruning cuts” or “minimize sap loss.”
Most often, these products are petroleum-based, but some even contain asphalt. Alternatively, there are natural tree sealers with ingredients like collagen and aloe gel.
Should I Use A Pruning Sealer On Trees? If So, When Do I Use Tree Sealer?
No – you should not generally use pruning sealers after pruning your trees or shrubs. The main exception is when trees like elms and oaks, which are susceptible to vascular wilts such as Dutch elm disease and oak wilt, have to be pruned during the growing season for safety reasons. In those exceptional cases, painting the wounds with latex-based paint will help prevent the spread of vascular wilts by beetles while also allowing the wounds to seal properly.
Research from the University of Arizona, found pruning sealers actually obstruct trees’ natural healing power. Yes, you read that correctly! Tree pruning sealers are bad they make it harder for your tree to recover.
Plus, pruning sealers may trap moisture in the tree, which can encourage wood decay or fungi.
While we need Band-Aids to reduce blood loss and help our wounds heal, trees simply recover differently than us.
How Trees Recover After Pruning
After pruning, trees grow new wood, which covers the pruning wound, and prevents the invasion of pathogens (diseases) or bugs.
Trees know how to recover from pruning wounds all on their own.
There you have it! Thanks again to Terri F. for submitting this question.
