The Q&A Archives: Root rot - now what?

Question: I have 2 gardenias in a shaded flower bed that I think may be getting root rot. The leaves are turning yellow, and the guy at Home Depot said that it may indicate root rot. So I backed off from all watering for about 4 days to let some further drainage happen, and now the top few inches of dirt are dry......should I give it longer or start watering again, just this time trying to be smarter about it?

Or (crossing my fingers that I'm wrong) is it already too late? The weather just turned really hot and I was overcompensating to try not to let them dry out. I hope I didn't ruin them!

Thanks for your help,

Answer: There are many things that can cause leaf drop. One is common - gardenias are very susceptible to spider mites, which cause tiny webs on the undersides of leaves and where the leaves join the stems. Another way to detect them is to take a sheet of white paper out to the bush, tap a few branches on to the paper, fold the paper in half and press/rub together. If you see little red, blue, or brown smears, those are spider mites. You can spray them off with a strong blast from the hose (do this daily until they're under control). A product called Neem can also be used to treat for spider mites. Follow product instructions for application. Gardenias need at least a half day of full sun to bloom, but at the same time, the hot afternoon sun can be tough on them. Morning sun is best, so an eastern location would be ideal. You might also try a southern or western exposure with some filtered shade. Buds that turn black or drop and bottom leaves that are yellowed are sure signs that gardenias aren't getting enough light. Leaf drop can also be caused by improper soil pH (gardenia require 5 to 5.5pH - on the acid side.) Yellowing and leaf drop are also signs of various soil nutrient deficiencies such as nitrogen, zinc, and iron. Finally, if the air is too dry, your plant will drop buds and leaves. Try sprinkling the plant every morning to increase humidity (and also discourage spider mites!).

To address your watering question, I'd thoroughly soak the soil, then wait 3-4 days and dig a hole near the roots. If the soil is still moist, you won't need to water for a few more days; if the soil is dry, it's time to water; if the soil is still soggy wet, it doesn't drain well enough (which can cause root rot). If this is the case, you'll want to dig your plants, amend the soil with organic matter, and then replant.
Hope these suggestions help!

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