Leaves suddenly falling off my ninebark
It's late September and the leaves are suddenly falling off one of my two potted ninebarks. I've had them for several years and this is the first time it's happened. The other one is fine and healthy. They are on a roofdeck and they get faint water with irrigation. Photos are attached.
The plant looks stressed. There may be several reasons for this such as lack of moisture, too much moisture, and/or limited root system in the container. This plant spreads from the crown and may be too crowded for the container. Each plant has its own root system and there may be factors that affect one plant and not another.
Lack of moisture or too much moisture can affect the root system. In containers you will have to check the soil moisture and water deeply. In dry weather you may have to check the soil moisture daily and water as needed. Do not overwater. Probe with a screwdriver and water when the top several inches of the soil dries out slightly.
Make sure the container has holes for good drainage.
The plant may also be pot pound and may need repotting into a larger container in the spring. You may notice roots growing from the bottom of the container hole and also roots wrapped around the inside of the container and roots on the soil surface.
We also notice landscape fabric on the inside of the container and this may also affect the root system.
At this point, check the soil moisture, repot into a larger container in the spring or plant in the ground if you have the space.
That all makes sense, but why the sudden leaf drop? It's all happened in the last 5 days.
Plants, like any stressed organism, reach a critical point when they can no longer carry on normally. Then they exhibit symptoms of stress. To humans, it can seem sudden, but usually it began slowly in ways we don't easily detect or are not detectable at all.
The longer one works with plants, the better one becomes at picking up subtle signs of stress or anticipating problems.