Tree pruning

This is a basic reference only, please research detailed coverage of this topic in gardening books or online.

Remove unwanted branches before treehouse building starts

• Prune branches in the autumn/fall or early winter when the tree is dormant - certain trees like walnut and maple should be pruned early to avoid bleeding sap and all Prunus species (eg, cherry, plum) should be pruned when in leaf to avoid Silver Leaf infection
• Consult an arborist/tree surgeon if you see any signs of dieback or if Sudden Oak Death is present in your area
• Use very sharp, clean tools
• Cut the branch outside the collar, not flush to the trunk
• Leave the cut clean and bare - coatings can encourage fungal infection

Don't attempt to remove large branches without training as there is a very real risk of serious injury/death. Likewise, only a professional should use a chainsaw in a tree.

Further reading

University of Minnesota extension advice on tree pruning
Bleeding sap - list of species at risk and suggested pruning times