OK, so here's my story. I had an azalea hedge out front that was not particularly healthy. One corner of it (about half of one plant) was dead when I moved in over two years ago. Another portion (again, about half of one plant) was badly stunted. I dug these up in spring (mid-March) and planted four holly bushes from Costco. I'm not much of a gardener, but the plants appeared to be quite healthy. (The plants have been in the ground since March 21st or so.) The sun exposure is about 6-8 hours during the day. After a month or so, I started noticing some yellowing and leaf drop on the middle two plants. After some research it seemed as though this was normal to the holly growth cycle, as the dropping leaves were near the bottom and the inside, indicating older growth, and new growth was evident on the outside of the plant. I wasn't worried about this. The outer two plants weren't showing any real new growth, but they weren't dropping many leaves either. The leaf drop stopped, as I read it would, and life continued. Today the middle plants have significant and noticeable new growth and some white blooms as well. (This is in the first image below). Now, the outer two plants seem to be struggling. My guess is either over or under watering (or some other consequence thereof) though I water them all equally. I water every third day or so in the morning; the soil is neither dry nor wet but damp. I used Hollytone when planting, and followed directions as well as possible (in a raised bed, slightly above ground level, and with mulch for moisture retention). We haven't been getting much rain; when we do I water less. The third image is the left plant while the fourth is the right plant. These plants are dropping leaves now - some (very few) are brown, but most look like healthy leaves (some of these are seen on the ground). The left plant is particularly worse - if you touch the leaves, they appear to simply snap off. Shaking, watering, wind - it seems like it takes very little to shake the leaves. However, the plants themselves appear healthy (branches are green inside). Both plants have very limited new growth. The last image shows something dark around the tips - I have no idea what this is but it doesn't look right to me. The second image shows the inside of the plant, which is sparse - there are some branches and at the top there is one leaf that is browning. Again, most of the falling leaves are green, but some are brown and look dead. A few inside twigs are dead. This isn't the case on the middle plants - they seem healthy and full, with the leaves firmly attached. Any idea what could be wrong? Am I watering too much or too little (or neither)? It doesn't make a whole lot of sense to me since the plants were planted in the same manner in the same soil and have the same care. Could it be that the end plants simply weren't healthy to begin with? If it's a watering issue, can anything be done about it? Any help is appreciated.
Here's a long thread on holly leaf drop, though I don't think your scenario is the same as the one discussed in that thread. I'm actually wondering if it has to do with the watering regime being on a fairly set frequency (in which case, I'd suspect overwatering). Unfortunately, I've no direct experience, so I hope someone else will pipe up.
