The infestation appears to be white. Og is deposited on the underside of leaves and at the base of areas that branch off.
It looks like mealybugs, a common pest problem with gardenias.
This article tells more:
https://www.gardeningknowhow.com/ornamental/flowers/gardenia/gardenia-pests.htm
Since we moved from Florida, where it could be out doors all year long, we now live in Pennsylvania so it must come in doors for the winter and we have 2 cats. Also, is the umbrella plant poisonous to cats? Thank you for your help. Eleanor
They are both mildly toxic if ingested. By umbrella tree, did you mean scheffelera? Here is more information:
https://www.aspca.org/pet-care/animal-poison-control/cats-plant-list
https://www.gardeningknowhow.com/plant-problems/environmental/plants-toxic-to-cats.htm
I'm currently using a Jobe's fertilizer spike to fertilize my gardenia plant. It is doing okay, but I want to do the BEST for my plant. What should I use?
Hands down, the best types of fertilizers are pharmaceutical grade. They are pure elements crafted in a lab, and filtered through micron filters to remove ANY solid particulate.
They are usually split into a 16 part system or more, though. They must be precisely measured, and only diluted into water. Then they must be pH balanced after.
The best nutrient systems are far from easy to use, since they require knowledge of how much of each element needs to be mixed in at any given time in a plants life. They are also expensive, running around 400 Dollars or so for a full kit that will last a year.
I recommend going with what is feasible, or natural for your area. There are many single or double part systems that are organic and granular, giving you the best of feeding with quality ingredients and storage ability.
Though We do not recommend certain brands, I would say that your best bet would be, either, compost added each year, or organic granular fertilizers geared toward acid loving plants.
This article will help: https://www.gardeningknowhow.com/ornamental/flowers/gardenia/fertilizing-gardenias-in-your-garden.htm
My gardenia plant - grown indoors in a pot - has gotten very “leggy”. Leaves are rich dark green and in 3 years has had one flower. Question: should I repot it with new soil, and trim back the longerst branches?
Yes, you do need to prune your gardenia, but it should be done at the end of flowering but before new buds are set. Here are some articles that detail the needs of gardenias and should help to get yours to bloom.
https://www.gardeningknowhow.com/ornamental/flowers/gardenia/growing-gardenias-indoors.htm
Here's an article with tips on how to winter over your gardenia:
https://www.gardeningknowhow.com/ornamental/flowers/gardenia/gardenia-winter-care-tips.htm
The leaves are crinkly and they have turned from dark green to a light green.
Inconsistent watering could be the culprit, causing drought stress. If you think that is a possibility then water it heavily right away and you may save it.
Another possibility is spider mites. They are hard to see but you should see webbing among the leaves. This article tells more:
https://www.gardeningknowhow.com/ornamental/flowers/gardenia/gardenia-leaf-curl.htm
This article and a soil moisture meter can help to take the guess work out of when to water:
https://www.gardeningknowhow.com/garden-how-to/soil-fertilizers/testing-moisture-in-plants.htm
My Gardenia leaves are turning yellow and droopy. I don't know what is wrong. They are in direct sunlight and get plenty of water when needed.
Although gardenias can tolerate some direct sun, they will need shade for most of the day. They do best with just a few hours of morning sun, and the rest of the day should be shaded, or dappled light.
They are also not cold tolerant, but this should be less of a concern in your area. They are fully hardy in your zone.
This article will give you more information on the care of these: https://www.gardeningknowhow.com/ornamental/flowers/gardenia/gardenia-plant.htm