Energy Balancing in Shrubs
Being basally dominant, many shrubs are going to do anything they can to kill off older parts and grow shoots from below.
The more geriatric the shrub, the greater the danger of killing off exactly what we want to preserve—the older, trunky bits. They don’t like to make trunks much, with the exception of Satsuki Azaleas, though even those will happily slaughter their tops in preference to the lower branches.
The following is an example of one way to manage basal dominance in an older shrub.
Older Chojubai growing good shoots off the lower branches but little off the trunk top, a common situation. This is roughly the opposite of a tree, which wants to lose the lower branches and preserve the leader.
In this situation, trim the lower shoots mid-season, usually in June or July,. Leave the shoots on the main trunk untouched, until fall, or maybe until the fall of the next year. This selective shoot pruning will, over one or two years, balance the shrub, retain relative energy, and help prevent the larger, older trunks dying. The same goes for older Satsuki Azaleas and others, should they show similar weakness. Younger shrubs are easier to manage.
You can think of this from a historical haircut perspective. Remember the mullet? On an older, top-weak shrub, cut off the mullet. Leave the poof on top (the pompadour). If you’ve a top-strong tree, give the top a buzz cut and grow out the mullet.
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2 Comments
Great tip, Michael.
What would the plan be with a quince grown in a semi-cascade windswept style? What’s considered the “trunk top”? What’s considered the “lower branches”?
Thanks.
This is a really good question. Usually a quince has a similar problem as any plant that is trailing: the lowest part can get weaker. The basal dominance tends to only relate to the root mass and not height of foliage.