As we all know, the heavy snow that fell this year was particularly hard on our delicate Japanese Maples.  The split may be bad enough to kill a large portion of your plant.  However, if nothing has broken off, it’s certainly worth trying to save.  What you have going for you is the fact that early spring is the ideal time.  With care you may be able to coax it to “grow back together,” so to speak.

One thing to keep in mind is that the center of the trunk is wood, no longer growing.  The growth is in the outer layers, the bark and cambium just behind the bark.  There is where the “growing back together” needs to take place.  With your maple, presuming the split is clean, realigning the cambium will be easy.

You’ll need these supplies: a can of aerosol air duster, drywall screws, and duct tape.

First, make sure there is nothing in the split.  Even though this heartwood isn’t growing, trapped foreign matter could result in disease or rot. Use the aerosol air duster – such as is used to clean computers or cameras – and, when conditions are dry, get any dirt or hemlock needles or whatever out.

With the tape, wrap the trunk tightly back together, so that the parts line up perfectly.  Now you can screw the trunk (using drywall screws) back together, one to two screws on both sides of the split to permanently hold the split together.  The reason for using drywall screws is that they are thinner than most.  After the screws are in place, you can remove the tape you used to initially hold the trunk together.  Finally, place a layer of tape over the split to make sure no water or debris gets back into the split to prevent disease and rot.

In about three months the cambium should have grown back together.  Carefully remove the tape to see if the split is healing. If it has not healed yet, tape the split back up and check in another couple months.  If the coming summer is a hot dry one, keep the tree adequately irrigated – the need is healthy growth so that the cambium and bark make a full bond.  There is no need to remove the screws.