911 Azalea Rescue

Greetings Bonsai Community,

I recently acquired a 60-year-old azalea (free) that hasn’t undergone repotting in over 40 years. Given its unique history, I’m seeking advice on the best approach to overwintering, considering its age and the extended duration since its last transplant.

The previous owner mentioned some insect issues, and while I’m noticed falling leaves, it’s challenging to assess the extent of the problem. Any insights on identifying and addressing potential insect infestations in mature azaleas would be highly appreciated.

I’m eager to learn from the experienced practitioners in this community. Your expertise will undoubtedly contribute to the well-being of this venerable tree.
Thank you in advance for your valuable guidance!



An update on the azalea: I removed a thick layer of moss, about an inch and a half deep, to promote better oxygen flow to the roots. Fortunately, it flaked off easily without any roots entangled. I also addressed significant crevasses in the root system by filling them with soil and applying sphagnum on top.

To tackle potential pests, I rinsed the undersides of the leaves, successfully removing most black spots and bugs. Considering the sensitive nature of azaleas to insecticides, I’m contemplating using a mild soap spray. I recall Ryan mentioning that azaleas might not respond well to traditional insecticides. Any insights or alternative suggestions regarding pest control for azaleas would be greatly appreciated.

Feeling confident about the current state of the tree, I’ve positioned it to endure upcoming cold spells. However, I’m now strategizing to prevent other trees from coming into contact with it. If any of you have similar experiences or differing approaches, please share your thoughts.

Thank you all for your ongoing support and guidance!


Based on the foilage spots and it being an azelas looks like lace bug. They are a pain but treatable and stay on top of the treatment until you break the adult/lava cycle.

I would start with neam oil early and often if you trying to avoid insecticides. I battle them in my landscape plants and also try not use insecticides and I honestly am still battling them and will give into a drench in the spring. I’m not saying you should, because Ryan would know best if they can or can’t handle Pyrethrin or not and if he advised against it I would listen. I would cross reference all of Peter Warren’s content you have access to or ask Ryan to call in favor if he doesn’t have a rough and somewhat viable treatment plan off the top of his head.

Knowing what metals this plant is too concentrated in might reduce the “attractiveness” to the lace bug but hard to say since it’s pretty rampant on Andromeda, azelas, boxwood and rhododendron across the US.

Predatory insects is an option but after you have them under control and based on the foilage damage it looks pretty infested.

Goodluck band I wish you knew a silver bullet for you.

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I read some studys where the azelas in full sun were infected at half the rate of semi shade (5 hours was the distinction for the study)… obviously in a pot everything’s is different but morning full sun afternoon under a shade cloth in a low humidity environment was why I thought for bonsai to potentially reap some of those benefits

Thank you for the tips, they are always welcome and needed! I’ll continue to do some more homework and I’m hoping the best for this tree.

I was looking into this if you want to do some homework, maybe ask Ryan in a QA ?

It’s a nice tree I hope you figure it out!

AgroMagen, GrowSafe Bio-Pesticide… https://www.amazon.com/dp/B07M983TRL?ref=ppx_pop_mob_ap_share