Pollarding mulberry trees (question from the extension service 3/20/17)

Thank you for your question about pollarding your mulberry trees in Albert’s Garden.

Pollarding, basically pruning the upper branches of a tree, is usually done in order to keep a tree from growing too tall, and in this respect, it can help with better light.  The new growth that emerges from a pollarding site is often thicker than “unmanaged” growth on a tree, so depending on the tree’s location, the amount of light that gets to nearby plants may or may not be increased.  While it does serve to keep a mulberry, which can grow to 50 or 60 feet if left unpruned, from blocking some light from getting to certain plants, the dense growth produced by pollarding can prevent light from getting to others.  If you send us a photo of the trees in situ, we may be able to give you more advice, but your familiarity with the Albert’s Garden site may be your best advisor in this decision.

Once a tree has been pollarded, a knob will form at the pruning site.  The sprouts that emerge from the knob will need to be pruned every year or two, as they are very weakly attached to the knob and in just a few years can become heavy enough to be a potential hazard.

As with any pruning technique, pollarding is often done to increase the amount of fruit, not decrease it.  Mulberries can be messy trees in this respect, and as you surely know, their juice can stain whatever it touches.  Not only will their fruit fall all around them, but it can also be easily tracked on footwear through the rest of your garden, on walkways and even into someone’s home.  People have reported removing the stains by using lemon juice or boiling water, but we have no personal experience with this.

It is commercially possible to prevent or at least lessen the formation of mulberry fruit.  It usually requires the application of chemicals by a professional, however, and it can be expensive.  If you want to go that way, please check with the City to be sure the chemicals your tree professional intends to use are approved under Local Law 37.

While white mulberries (Morus alba) can live for a century and red ones (M. rubra) rarely exceed 75 years, mulberry trees grown in landscapes usually live only 25-50 years, which means that your 40-year-old specimens may need to be replaced in the foreseeable future, at which time you may wish to consider other plants for their space.  If you want to replant mulberries for sentimental reasons, you should either plant all male trees or a non-fruiting variety like M. alba ‘Fruitless’.

Hope this helps.