When to prune a winter-indoor gardenia
When to prune a winter-indoor gardenia that buds but doesn't bloom? I have two gardenias that I purchased late last spring as bare root plants, which were supposed to be "trees." This might be a 2 part question, I guess. 1) Can I force them to bloom? They have been consistently producing buds since I put them into planters, but they fail to bloom. Some buds clearly don't even form petals inside, and the buds that are fatter usually drop off before they open. Also, some leaves will turn yellow and come off easily. 2) What is the best way to prune them so that they are eventually "tree" shaped? I've read that it's best to prune after blooming, but what if this never happens? What if it blooms right before summer? DETAILS of GARDENIAS LOCATION: They are outside when it is warm (late spring to mid/late fall), and inside during the winter. LIGHT: Both locations are south facing, although inside the sun is not quite direct (I don't wake up early enough to push back the curtains, which filter but do not block sunlight). WATER: I usually water thoroughly when the soil is dry or dryish. This is usually about 1xweek or week and half. I try to water only in the morning or evening. FERTILIZER: I try to remember to fertilize once a month, and have only acidified a couple times within the last 4 months. PESTICIDES: I tried using horticultural oil, but it seemed like it was too harsh for the plant. I now swab aphids off with a q-tip using a mixture of (very little) unscented castille soap and water. We had a really bad infestation in December when we went out of town, but it's almost aphid free now. HUMIDITY: Possibly too dry? They are not in the direct path of the heater, but it is probably less human than they like. I try to remember to leave a bowl of water in one container if there isn't any water in the rock tray under the gardenia.
Certified GKH Gardening Expert
Your gardenias actually look like small trees, they just need time to grow taller trunks. Most gardenia trees I have seen have long trunks with an orb or branches/foliage/blooms at the top. When you prune, you could trim some of those longer branches that are popping out from the rest to keep a more rounded shape.
I would go ahead and prune when those gardenia buds are past the point of no return. That way you are giving them enough time to bloom if they decide to bloom.
Yes, there are ways to force them to bloom and the following article will assist you with that and yes, humidity does play a role.
Here is an article that explains the many reasons for bud drop, one of which is a change in location - gardenias do not like to be disturbed.
I also think you need to totally eradicate your aphids as aphids kill flower buds and cause yellowing leaves. The following article will give you some more organic solutions for dealing with aphids: