Some of the leaf ends are brown.
There are quite a few requirements needed before they will bloom. These articles should help:
https://www.gardeningknowhow.com/ornamental/flowers/gardenia/gardenia-care-to-get-a-gardenia-bush-to-bloom.htm
https://www.gardeningknowhow.com/ornamental/flowers/gardenia/growing-gardenias-indoors.htm
Should gardenias and jasmine be covered to protect them from cold weather in the 40 and 30s? Joancunha88@gmail.com
Depending on the cultivar, you will need to protect them from cold weather. If you do not know, exactly, which you have of each then you will want to take the extra precaution and protect them anyway.
These articles will help: https://www.gardeningknowhow.com/ornamental/flowers/jasmine/growing-jasmine-plants.htm
https://www.gardeningknowhow.com/ornamental/flowers/gardenia/gardenia-plant.htm
https://www.gardeningknowhow.com/ornamental/flowers/gardenia/growing-gardenias-indoors.htm
I started a gardenia house plant from a cutting and it is healthy and growing nicely. When do I cut it back so it will 'bush out'? You'll notice on the photo there are two new leaves coming out from a leaf joint half way down the main branch.
I would wait a little longer. It looks very young yet and pruning could open it up to disease. Here is more:
https://www.gardeningknowhow.com/ornamental/flowers/gardenia/when-to-prune-a-gardenia.htm
Affected leaves have "new growth" but they do not grow into new foliage. Should I cut those leaves off?
This sounds like it could be a bacterial infection!
I would recommend, only, cutting off the infected leaves. It will, also, benefit from a fungicide. This article will help:
https://www.gardeningknowhow.com/garden-how-to/info/using-fungicides-in-garden.htm
This usually happens from overwatering, or soils that remain too moist for too long. If you can keep it from getting watered until the top two inches of soil are dry, then it will reduce infection. If this is not possible, then you will need to treat with fungicide often.
These articles will help you to care for Gardenia plants: https://www.gardeningknowhow.com/ornamental/flowers/gardenia/gardenia-plant.htm
I'm transplanting a Gardenia from the pot that it had when I bought it to a new pot.
They are best suited for an acid-loving potting mix. This will give them the pH they need along with the proper drainage.
These articles will help you to care for the plant:
https://www.gardeningknowhow.com/ornamental/flowers/gardenia/growing-gardenias-indoors.htm
https://www.gardeningknowhow.com/ornamental/flowers/gardenia/gardenia-plant.htm
I have a gardenia plant in the house and last year it bloomed with many flowers, this year it has many buds but the pot is too small. When can I transplant it to a larger pot. Spring? Summer? Fall? or Winter? Thanks
I would wait until after a bloom cycle to repot. This article will give you more information on their care:
https://www.gardeningknowhow.com/ornamental/flowers/gardenia/growing-gardenias-indoors.htm
These Gardenias have been propogated and are growing well but it gets buds on but they fall off and don't flower.
This is such a common complaint that we have an article to help you!