Pruning Japanese Blueberry to Encourage Growth

Q. I have 13 Japanese blueberry's they have been planted for quite a few years. They have grown tall but only one filled out from the bottom to top because of some shading. This shading is now gone. What can I do and when to stimulate the growth and hopefully have them fill out all over. 

Japanese blueberry picture from another reader.

 A. Severe shading can cause branch or limb dieback. Reduced light to branches can also cause leaf drop and poor growth on living wood.

What to do? Determine if these branches are alive or dead. If they are dead then all you can do is remove them back to the trunk or back far enough to healthy wood. Grasp these branches and bend them. Dead branches will snap like a dry or dead twig. Living branches will bend and not break as easily. If you bend a living branch back far enough of course it too will break so you have to be careful when bending them.

Wait and hope.If they are dead and you have pruned them back, all you can do is wait and hope that light reaching inside the plants will “sprout” new growth and fill in over time. If they are alive then do not prune them all the way back but cut off just a few inches of the ends just far enough to cut into living wood.

Dead branch of Japanese blueberry from another reader.

This might be one or two inches or six or more inches depending on where living wood is located. These types of cuts are called “heading cuts” and remove the terminal buds and will stimulate the plant to fill in bare areas.

When to do this? Do this in about early to mid-February next spring. Fertilize the plants at that time with a tree and shrub fertilizer or even a lawn fertilizer and give the plants a two or three deep waterings with a hose a few days apart. The water from the irrigation system will move the fertilizer into the root area. The fertilizer should be a high nitrogen fertilizer. It would be helpful to give them some iron applied to the soil as well at the same time.