Problem with one azalea #745837 - Ask Extension

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Problem with one azalea #745837

Asked April 23, 2021, 10:57 AM EDT

This spring we planted 10 "Hino Crimson" azaleas along the front of our house, replacing the scraggly ones we planted there in 2017 (Rosebud and Elsie Lee). The front of the house faces WNW, and gets mid to late afternoon sun. One of the original azaleas actually died and we pulled it out, last year or the year before. The 2017 azaleas we moved to the back of the house, where we back up to parkland and scattered tall trees give dappled sunlight - hoping they'll be happier there. The new shrubs looked good, on the verge of blooming when we put them in, and blooms popped open within a week, with the exception of one - in the same location as the one that died before. I'm trying to figure out why. Attached are a coup-le of photos. The sad one is number 7 from the front door, 4th from the end. It is not in front of the outdoor faucet (the 2 there are just fine) but is in front of the kitchen window, near the edge of the house and the downspout, which drains under bed off the side of the house. For now, I dug up the azalea, excavated a larger area around it, and filled it with 2 40lb bags of top soil with Holly-Tone mixed in, and replanted the azalea. When I dug out the dirt, I didn't find anything I thought unusual - a fairly large rock, some large thick roots from other long gone shrubs, and one very disappointed squirming cicada larva, but nothing else. The other shrubs' blooms are done, and I don't expect this one will do anything to catch up. I'm just hoping it won't die by next year like its predecessor. Is there anything else you can recommend we do to try and keep that plant healthy? Or do you have recommendations of something we need to fix or look at with that location besides what I've already done? Thanks! This is the 4th time I've sent in a question, and your team has always been responsive with, if not answers, at least great ideas and information! Thank you!

Montgomery County Maryland

Expert Response

The amount of direct sun this bed is exposed to might be a bit high for azalea preferences (during summer, a least); it's hard to tell since western sun is stronger and the mid- to late afternoon timeframe suggests the light persists for possibly 5-6 or more hours worth. Azaleas being woodland-adapted can struggle in sites that receive too much strong sunlight, especially backed with a heat- and light-reflective/radiative surface like a brick wall. While this doesn't necessarily explain the ailment of the struggling lone plant, it is a factor to consider that can contribute to the vulnerability of the plants to other issues. If the sun isn't that intense here, then the exposure should be fine.

It's possible the root system on that single struggling plant wasn't in as good a condition as the rest when it was planted, and the transplant shock took more of a toll on its condition. Flowering on spring bloomers like azaleas primarily takes place as merely the absorption of water to expand the buds, since bud development itself occurred last summer/fall. Thus, if buds or subsequent new leaf growth fails to open, that suggests the root system isn't functioning properly or has insufficient moisture (usually the former, especially since the latter is easy to monitor). Azaleas are very sensitive to over-watering and poor drainage; while you mention the low likelihood of that being an issue here overall, drainage can be surprisingly varied even within a bed of this size. It's also possible its root health was compromised by water issues before it was purchased, as such circumstances can take time to reveal symptoms, especially with evergreens.

In the future, it's best to not use pure amendment in a planting hole, but rather to mix it in thoroughly with the existing soil. Use minimal amounts of amendment, as the more of a difference in soil types there is between the planting hole and the surrounding soil, the greater the likelihood the roots will respond negatively when eventually encountering native soil; plus, this creates drainage problems as water doesn't move through the two soil textures in the same way. Approximately a couple of shovel-fulls of amendment (topsoil, compost, and/or fine-grade pine bark mulch) should be sufficient to amend the soil for a single shrub of this size.

Similarly, make sure root balls are well-loosened upon planting, as those bound from their time cramped in the pot will struggle to reach-out into the surrounding soil to establish themselves. Azalea roots grow relatively shallowly - often not even filling the pot to depth - and so become fairly easily entangled and matted when reaching the edge of the container.

Holly-tone is a suitable fertilizer for acid-loving plants, but should not be needed for either freshly-planted or even established shrubs unless signs of nutrient deficiency appear. Too strong a nutrient level can actually damage roots, though fortunately organic fertilizers like this break down more slowly than some synthetic formulations. You don't need to worry about the fertilizer you already applied, but we don't suggest using more at this time.

For now, just monitor the plant's status, check for watering as needed, and see if it puts out new leaf growth. (Not flowering isn't too troubling a sign by itself if all else looks good.) If you don't see signs of active growth by May or June, the plant may be too compromised to recover. If the existing older foliage appears to stay healthy throughout the spring and summer, then perhaps this year's growth buds were damaged due to cold or water stress and the plant will have to wait until autumn to grow more for next spring.

Miri

Mira Talabac Replied April 23, 2021, 1:26 PM EDT
Thank you for such a detailed response.  I will watch for the things you mentioned, though I'm not sure many of them apply.
- the sun doesn't hit these until about 3 in the afternoon, when it finally gets around the corner of the house and heading towards setting, and seeing other azaleas in the neighborhood that are thriving with more sun, I don't think that is contributing.  We'll see as the year(s) progresses.
- We bought all 10 azaleas at the same time at the same nursery, and they were all the same size and condition, so I don't think we had one with roots in any worse shape than the rest.  We also planted them all the same way, mixing a little top soil with the existing soil (in the holes vacated by the previous ones) and freed the roots as much as we could.  My husband typically uses Holly-Tone, and mentioned it at the nursery, and they agreed that's what they would have used if we had asked them to plant them.  Choosing to widen this one hole and use new top soil was strictly a Hail Mary on my part, since there wasn't anything else I could think to do.
- in truth there isn't anything I'd be concerned about if it wasn't for the fact that 9 out of 10 are looking awesome, and the one looking poorly is in the exact same spot as the previous casualty. Plus the only "poorly" about it was the blooms failed to open, but just died in place.

Again, thanks for such a quick response.  I'll keep an eye on it and monitor it as you suggest.  On the plus side, the straggling ones we moved to the back are looking promising. (grin)

Renee


On Fri, Apr 23, 2021 at 1:26 PM Ask Extension <askextension@eduworks.com> wrote:
Renee Shields-Doyle Replied April 23, 2021, 6:39 PM EDT

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