Early Fall is always a good time to look over the garden and determine which individual plants haven't done well over the growing season, and then to assess blame and amend our gardening practices to allow us to improve next year. At issue, though, seems always the uncertainty of the cause of the failure.
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Looking around the yard, I also have decided that I finally am giving up on a Weigela florida ‘Wine and Roses’ in a lower bed because it never did leaf out well this spring. It has been in the spot for 3 years, now a four by four foot bush, but while it did well in the previous years, it never got going this time around. It put up a spare few leaves in the spring at the tip of the stems and then, as the spring continued, those leaves collapsed and dropped off. Was it the colder winter we had last year? If so, why did another 'Wine and Roses' exposed to the full northern wind in a raised bed survive just fine? Was it the wet spring and my clay soil? Did it develop root disease of which I'm unaware? What can I learn from this other than to put something else, say a crape myrtle, in its place?
I'm also perplexed at the seeming collapse of an enormous Sambucus nigra ‘Beauty’ elderberry that's been growing in the same spot in my "peony" bed for 6 years now. This dark burgundy finely-leafed specimen is surrounded by three yellow-foliaged shrubs, making a nice dependable contrasting foliage spot in my garden. Yet, two weeks ago, there it was, leaves completely gone and bare stems covered only by an invading green wisteria vine from nearby. What the heck? Another drought victim? Insect raid? Cold damage? I think it had started out the year well, but now, I can't remember for sure if it bloomed as expected in the spring. All I can do is cut it back and hope it grows out again in the spring.
I hope you learn what you can from your own gardening disasters this year, but if not, you're in good company. I, for one, have learned only that I have a lot left to learn about gardening.