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I planted this Gardenia a month or so back. Over the last several weeks, I am noticing more and more leaves are getting curled, although they do not turn yellow or fall off. On the other hand, they look quite shiny. To add to this, I see some leaves just give the look that they are being "consumed".
Reading various resources, I'm confused as to whether this is aphids, ph problem, moisture problem, or all/none of the above.
Please help. I'm posting a few pictures to give you a sense of both these issues.
Hi, without going into my books, it looks like at least one problem may be slugs or snails. The leaves are shiny because gardenia leaves are natually shiny. The holes look like slug/snail damage. You may also have other insect or pest problems. At a galnce it doesn't look like nutrition. However, have you checked the pH of your soil and what the gardenia's requirements are? Good luck, this is one of my favorite flowers!
Thanks for the responses. AFAIK, Gardenia is an acidic soil loving plant. I gave it an acid plant food 3 weeks back. Prior to that, I did test the soil and found it to be neutral. However, the leaves continue to get curled (even the new ones).
I've got a book on tree & shrub diseases, when I get home from work tonight I'll look and see if it says anything about what causes curled leaves. I'm pretty sure there are some insects that can do it, as well as possibly some sort of nutritional deficiency but I can't remember what deficiency causes it off the top of my head. If it was aphids, you'd see them on the plant and I don't see any in your pics. I've had spider mites on gardenias and they made a stippled yellow pattern on the leaves (which you may have...it would be worth checking the undersides of the leaves for them) but they didn't make the leaves curl. I also suspect that the yellowish spots, the curling, and the holes are not all caused by the same thing, you may have 2 or 3 different things going on there.
Thanks Ecrane3! Suspecting this might be aphids, I had washed the plant with shower from hose prior to taking the photos.
Also, I'm a bit worried now that I remember that last year I planted a few double impatiens at the same spot, and they never looked healthy. This time, before planting the Gardenia, I was extra cautious, and dug a pretty wide hole, and added some acid food at the time of planting. I also keep in mind that Gardenias like to be moist and that the base should be above the soil line.
Do you think spraying a horticultural oil like Rose Defense would help? It shouldn't hurt anyway, right?
Yeah, lime probably wouldn't have made them too happy...whether it killed them or not I don't know but it certainly didn't help them any!
prabal--I checked my pests book and didn't find any new ideas on insects/diseases that would cause symptoms like yours. Then I checked the 2nd book in the series which covers abiotic disorders (things resulting from cultural conditions) and came up with a few possibilities. I would definitely check your soil pH, I suspect it may be too high. The yellowish coloration didn't look exactly like iron chlorosis to me, but magnesium and zinc deficiency give the leaves a different pattern of yellowing, and zinc deficiency can create some puckering. Most likely there's Mg and Zn in your soil as well as Fe, but if your pH is too high then the plant can't absorb any of them effectively, but once you reduce your pH then the plant can absorb them. I'm not sure if the puckering will go away on the existing leaves, but as new ones grow you should see that they don't have it. The other possibility is herbicide overspray, it can cause leaves to look like that too. So if you (or your neighbor) had sprayed any sort of weedkiller and the wind blew it onto your gardenia that could do it too. I also still think there's a possibility that you have spider mites too on top of some sort of cultural problem so I'd definitely do a due diligence check for them too.
Hi ecrane3, since you mentioned herbicide, it just occurred to me that last fall I did spray some insect killing solution quite heavily right in that zone since a big ant colony was developing there. Could that have caused it? It's possible, since as I mentioned, the double impatiens also kept struggling and eventually died.
Anything I can do now, or is it a persistent damage?
If your pH is up near 8, you will probably need something more than acid lover plant food to lower it. If your pH is still around 8 now and you added things to the soil 3 weeks ago, I don't think it's all of a sudden going to be below 7 in another 3 weeks if you don't do anything else to it. So I'd recommend making a more concerted effort to reduce your pH, look for some sulfur or some other amendment that will lower the pH more effectively.
As far as the Rose Defense, I personally wouldn't use it. I don't think your problem is caused by aphids, so unless you actually see some on the plant I wouldn't treat for them. On the other hand if you see some then feel free to use something to get rid of them, although now that weather's getting warmer I'm not sure a horticultural oil is the best thing, I'd probably opt for insecticidal soap instead. But I wouldn't apply anything unless you actually see some aphids on the plant.
And for the insecticide...if the impatiens was there when you were doing it and you used a lot, then I could see that it might have hurt them, but I doubt if there would be any of it left now to cause harm to the gardenia.
If you can get your hands on some peat, then this will help the roots some, everyone is right, they like acid soil, till you get your soil sorted and to save your plant, as it has been newly planted, I would be inclined to lift the plant out the ground and pot it up with the proper acid plant compost you can buy from the garden center, I also find rain water better for watering these plants as it is inclined to be more acidic than tap water, by potting your plant till you get the soil right, it will save the plant and you can always replant it in the fall when the weather is cooler, by then you should have a better balance to the soil too, it may well be that you really cant grow acid loving plants in your garden as the soil is just too neutral, so maybe even plunging a large pot into the earth with acidic bought soil will be the way to go for this type of plant, remember adding acid adjusting things to the soil might only be a temprary thing and each year you may come across the same trouble soil wise.
As for the holes in the leaves, look in the evening for things like earwigs (insects with little pincher's at the tail) they eat holes in plants but unlike slugs/snails they dont decimate the whole leaf/foliage, the yellowing on the leaves are definitely a soil problem. Ants will thrive in areas where there are aphids or other insects that they have as a ready supply of meals, they especially like the honey dew that the aphids excrete and dont eat the aphids, this secretion can lead to a black mould forming on the foliage, so it is important you check evenings as well as in the day time. Good luck. WeeNel.
Thanks all for all your responses. I agree with most of the observations made here. I'm going to go for a sulfur treatment to see if that helps the amendment (ecrane3, do you know how long does it usually take for an appreciable change to occur in pH if done this way?). If I continue to get curled up leaves, I'll go for a large pot and dig it inside in the same spot (thanks WeeNel!)
Meanwhile, the other Gardenia Veitchi that I planted in another spot produced its first flower. It's intense fragrance brought back memories of my childhood in India where this is a very common plant.
It can take a while for the plants to show any marked improvements and the yellow leaves might never turn green again, but they may fall off the shrub, also remember, your amendment will only be temp and you will need to keep doing this every so often as you are really growing a plant that is totally unsuited to your soil type, I would get it into a large pot with ericaceous soil specially for these types of acid loving plants and then sink the pot into the ground up to the top, this way, nothing from your garden soil will be leaching into the roots of your acid loving plant. unless you are prepared to change all the soil in your bed, then you could be fighting a loosing battle, another thing some folks do to grow acid loving plants in the wrong PH, is to make a raised bed and add acidic only soil to this,
Good Luck. WeeNel.