Hey there! I live up north, and put my gardenia in a pot. It had many buds on it when I bought it, but all but two dropped off. Now I am getting new foilage, but it is much lighter green. I have no idea how to fertilize this, and plan on wintering it indoors. Any thoughts?
Most likely it is losing blooms/buds due to spider mites, who love heat and humidity. Spray with a weak solution of mild soap and warm water, every 3 days, until they are under control, then every 7 days to keep them in check.
Bringing it inside also shocked it which could have caused the bud drop. Are your nights below freezing already? Most gardenias can take a little bit of cold. For fertilizer, since it is inside, you can use pretty much any good quality liquid food. I would use either a very weak solution every watering or half strength 2 times a month, you don't want to push too much growth while it is indoors. I top dress any pots I bring in with worm castings and find it helps keep the critters like white flies, spider mites and fungus gnats at bay.
Karrie, your gardenia needs acid soil, humidity and warmth. Get some sort of acid-lovers fertilizer, something recommended for azaleas and rhodo's would be perfect. They are very subject to iron chlorosis, so make sure whatever fert you buy has an iron component (it will say so on the label).
I was born in Trail, BC, and spent my summers at Christina Lake just to the north of you there, so I know it is hot and dry in summer there. IF you keep your gardenia outdoors until the nights get cold, it should be in partial shade - morning sun is ok. But it needs higher humidity than you probably have, so near a sprinkler, tub of water next to it, put a spray bottle of water near it and mist it every time you go by. Do everything you can to increase the humidity around that plant.
Same in winter when you bring it in. A sunny window would be fine since you are that far north, but do your best to keep the humidity high. A plastic tray with pebbles that you keep flooded with water will help a lot. It's good for the people in the house as well!
Since we are talking about gardenias, I have a question. I have had a little gardenia tree all summer and it has actually grown quite a bit since I've had it. About mid to late July, all of the buds were spent and it hasn't flowered since. Are we out of blooming season for them? Or did the scorching summer heat (100+ for weeks) do a number on it? It looks perfectly healthy, and has quite a bit of new foliage, just no flowers or buds. I weakly fertilize every couple weeks, but have not used an acidic fertilizer in a while. Thanks for any help.
Jaime, most gardenias bloom wonderfully for about a month here, in April - May. Then they are just nice foliage shrubs the rest of the year. Since your summer heat arrives later than ours, June into July might be about right for one to bloom in MO.
August Beauty, the one Karrie has, is a hybrid that re-blooms through the summer. But I'm betting they only re-bloom when the nights are cool, too.