Should I seal or paint over pruning cuts on my trees?

This is one of the most common tree care myths. In most cases, NO — you should not apply wound sealant, tree paint, or pruning paste to cuts. Research conducted over the past 40+ years by Dr. Alex Shigo and others has conclusively shown that wound dressings do more harm than good.

Why wound sealant is usually bad:

• Trees compartmentalize wounds naturally through a process called CODIT (Compartmentalization of Decay in Trees) — they wall off damaged tissue rather than "healing" like animals do
• Wound sealers trap moisture behind a sealed surface, creating an ideal environment for decay fungi
• The dark surface of painted wounds absorbs heat, which can damage living cells at the wound margin
• Sealants can actually slow the formation of callus tissue (the "wound wood" that gradually closes over cuts)

The ONE exception — oaks in oak wilt areas:

If you must prune oaks during the growing season (April-October) in areas where oak wilt is present, immediately paint the wound with latex paint to deter the sap beetles that spread the disease. This is the only scientifically supported use of wound sealant.

What to do instead of sealing:

1. Make proper cuts — just outside the branch collar at the correct angle
2. Use sharp, clean tools for the smoothest possible wound surface
3. Let the tree do its thing — a properly made cut on a healthy tree will begin forming callus tissue within weeks
4. Keep the tree healthy — proper watering, mulching, and avoiding soil compaction help the tree direct energy toward wound closure

For more on proper pruning technique, visit our Pruning Calendar.