Hey Rebecca,
Glad to hear from you again.
"The first thing that helped turn the issues around was patient guidance from Helen at the Botanical Garden's Plant Hotline. She gave me the same general advice about watering, and it's evolved that once a day is a good schedule. About two weeks ago, even though there was no sign of a new problem, I got worried again about over watering. I cut back to every 36 to 48 hours, and pretty shortly after the change, there was another batch of yellow leaves. There weren't as many as before, and since I've returned to daily watering, it doesn't seem to have developed more than a few additional ones."
I am glad the Botanical Gardens was able to assist you in this matter. Watering can be a tricky thing to get under control, but if your plant responds positively to whatever watering schedule you give it, then you know you are on the right trick. It is crucial to observe how the plant responds to different stimuli (water, sun, winter care, feeding, etc.) and adjust accordingly. It seems like you may be honing in on the proper watering for this particular tree. However, the yellowing of the leaves may be do to over-watering, but it may also have to do with something else, such a nutrient deficiency, high pH, or pests. If the tree seems to be doing well with the watering schedule, then continue as you have been. Try to amend the soil with some nutrients (I'll get to this in a bit), and see if the yellowing subsides. If it doesn't, then check to see if pests could be a problem, or some other mineral deficiency, like iron or magnesium. If all else fails maybe try to alter the watering slightly more and see if you get positive results.
"Its sun exposure is about 9:00 to 1:00 every day, and since its leaves are a healthy green, I'm assuming that's adequate. I rotate it 180 degrees once a week so that it can get sun all around."
This seems pretty reasonable. If the tree is doing well under these conditions, then don't change.
"Is it safe to trim a few of the branches that lost the most leaves? And if not now, when is a good time?"
If there was some die back on the branches, then I would clip back to the healthy leaves. Do not do a severe trimming just yet. It does not seem like the tree is 100% healthy to trim it down a lot. Trimming dead ends from die back or blooms is fine. However, I would try to leave the most leaves as possible to maintain the trees energy.
"The plant was shipped from Mississippi, and I understand that's the source for most of the bonsai gardenias sent in the spring. It came with a small set of instructions that included "...waiting at least one growing season before repotting." I'm assuming the growers/shippers are well enough acquainted with its needs that they would have picked a soil mixture that would be at least adequate, but please let me know if that's not the case."
Waiting one growing season is reasonable. However, if all else falls in turning around your tree, you may have to repot it into better conditions (pot, soil). The best time to repot is in the spring, but the fall may offer another alternative for gardenias. Repot as a last resort. Try to adjust all other factors first.
"When should I fertilize/feed it?"
Feeding should be done from spring to fall. No fertilizers (at least none with nitrogen) should be given in winter. Everyone has different opinions, perspectives, likes and dislikes, and schedules for fertilizing. To keep things simple and short, I'll just tell you what I do with my trees, herbs, and house plants. I use a solid, pelleted fertilizer (instead of a liquid) and sprinkle every 3-4 weeks during the growing seasons. I use a fertilizer called Happy Frog. They make one for acid loving plants (http://foxfarmfertilizer.com/item/happy-frog-acid-loving-plants-fertilizer.html), such as gardenias. Amazon has it in their store
www.amazon.com/FoxFarm-FX14065-Happy-Loving-Fertilizer/dp/B002JLGGXI/Local garden centers should have something similar to this if you don't want to order online/Amazon, or wait for it to ship to you. I tried to find if this fertilizer also supplements iron, but I had no luck. Whatever fertilizer you decide, check to see it is contains iron. If it does not, you may need to further supplement with chelated iron; you should be able to find this supplement in most garden centers. Magnesium may be another mineral that may be needed as well. Again, check the back of your fertilizer and see what it contains first, before adding anything else as a supplement.
"When the weather turns cool, I'm not going to know what to do! So I'll be posting again, and I hope I can maintain its condition for now. Anything you can share to help me is greatly appreciated."
For the winter, you will need to protect the tree in colder temperatures. Since it is in a pot and more vulnerable, the roots/pot will need to be protected from drying out. Some sort of shelter from the wind and freezing temperatures will be recommended. This is key, so start looking and planning for a spot to move the tree to on colder nights (maybe even days). You are more than welcome to come back before winter fully sets in and ask anything that you need.
Here are a few online guides for gardenia care. Feel free to take a look and use as needed.
General Care:
www.garden.org/plantguide/?q=show&id=2135www.wikihow.com/Care-for-Gardeniaswww.southernliving.com/home-garden/gardens/southern-gardening-gardeniaYellowing Leaves Issue:
www.gardeningknowhow.com/edible/helping-a-gardenia-bush-with-yellow-leaves.htm There is a lot here, so if you need clarification or further explaining, please let me know. I hope I made some sense of things. Good luck, and report back with any results or further questions you may have.
