Three Azaleas—Three Techniques

At the end of their spring blooming period, these three Satsuki azaleas needed attention. Each one came with a different puzzle. What to do?

I’ll let our answers unfold in the photo essay. Enjoy!

This Satsuki ‘Kinsai’ has a common geriatric problem. It hasn’t been pruned back in a long time. The whole tree is broad—well beyond its ideal canopy size—and has become sluggish. The next stage is branch death, most likely in the crown. Where it’s weakest.

Halfway done with a major cutback. Right after flowering this is possible, deep into wood. This allows a profile reset to inside our preferred canopy size. We expect a lot of shoots to come from this, which we’ll work to ramify out once more to a suitable profile size. For azalea this is periodic work.

Maciek ghosting behind our azalea. Interesting how the azalea looks frozen in space.

Satsuki ‘Kinsai’ pruned back.

This Satsuki ‘Yamato’ specimen is very strong. The opposite of the last one. This time we’ll use its energy to redirect the growth, using the “fishtail” technique to create ramification. This will slow the tree down.

Here’s the azalea after removing the last flowers, and after “fishtail”:  selecting two shoots to keep, then cutting back those shoots so only two leaves remain on each. The regrowth from this will be short and dense. The crown needs better structure, a job for another day.

Finally, this Satsuki ‘Toyo‘ is imbalanced, shown by the thinner foliage on the main trunk and the denser foliage off the low left branch. This azalea needs energy management, and partial defoliation is a trick that can correct that. If we do nothing, the main trunk might continue to weaken and the large left branch could take over.

Partial defoliation applied to the low strong branch, leaving the top alone. We identified the weakest part of the tree and matched it by removing old leaves from the strongest area—equalizing the sugar potential (one way to think about it). The summer shoots on the main trunk are so short that this Satsuki would weaken if we applied the “fishtail” technique. This is like choosing to skip a year decandling a black pine.

8 Comments

  1. David Johnson says:

    Thanks for sharing your various approaches. Allows me to better understand the science behind the techniques.

  2. Karen Harkaway says:

    Michael, thank you for this very informative article. I think many of us are aware of the various techniques, but often are unsure as to how and when to apply them. This is great!!

  3. Steve Gibson says:

    Michael – do you have any technical guidance on the fishtail technique? I haven’t come across this before and was unable to find reference to it anywhere. Thanks in advance!

  4. John S says:

    Interesting Article Michael!

    Wondering what was the rationale used in deciding not to simply cut back the left lower branches on the Toyo as in the first example vs partial defoliation?

    It appears from the photo the left lower branch is pulling well more then it’s share of the resources, indicating perhaps the sap lines feeding this area are more developed, maybe beyond simple basal dominance.

    Or perhaps would this be a next step if this doesn’t work?

  5. James O'Callaghan says:

    Great looking azaleas, how old would they be? They are a great species to grow i have many but not that size

  6. John Wiessinger says:

    Your 3-part offering on azaleas is EXTREMELY valuable!!! Thank you so very much for sharing this. This addressed several questions I’ve had with my own trees. Keep up the great work!

  7. Susie Nolan says:

    I am curious why there wasn’t more foliage left on the apex of Kinsai, given this is the weakest part (and typically weakest with Satsuki) of the tree. Perhaps the photo of Kinsai pruned back is deceiving.

    • crataegus says:

      Hi Susie,
      Thanks for the comment. Yes, that can be a consideration. Given that this tree wasn’t displaying any crown weakness, I cut fairly uniformly. When you cut so strongly everywhere, some of the top / bottom problems on azaleas (and on pines the reverse) tends to be minimized as you essentially make a high pressure system where it will push everywhere, strongly. I’ll post again about this tree with the reflush it’s had.

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