How do I keep my white hydrangea staying white?
Unlike blue and pink hydrangea, white does not need anything special in the soil to stay white. You may see some greening, but this is normal. Here is more information:
https://www.gardeningknowhow.com/ornamental/shrubs/hydrangea/green-hydrangea-blooms.htm
How do you protect hydrangeas from flattening in a rainstorm?
A healthy hydrangea should be able to stand up to a rainstorm ok, which indicates to me that yours is "leggy" or has weak stems. Leggy plants normally happen when a plant is not getting enough light. While hydrangea like shade, they do need some shade and if they are in too deep of shade, they may develop weak stems. Another indicator that they are not getting enough light is if you get few or no blooms on the plant.
Another possibility is that the plant is not getting enough nutrients to grow properly and this is resulting in weak stems. If you feel this is the case, give the plant some balanced fertilizer.
I have a very old hydrangea from my aunt and I want to plant it in a pot because the winter in Michigan can be so severe. How big of a pot do I need? Does it require peat moss or something like that? How much drainage?
The size of the pot depends on the size of the plant. You want it to be 2" larger than the rootball. Use potting soil, not topsoil, and there should be drainage holes at the bottom of the pot.
I received the most beautiful, huge hydrangea for Easter, and I live in Florida. It was purchased from Sam's Club. I am wondering if it will grow here in the heat we have in the summer time?
I live in east Tennessee and we have a Hydrangea. We've had it for several years and it will not bloom. It is in full sun. At one time it was in the shade. It has beautiful foliage but will not bloom. Can you tell me why?
Here is an article that you may find helpful: https://www.gardeningknowhow.com/ornamental/shrubs/hydrangea/hydrangea-not-blooming.htm
I have a Hydrangea bush that has never flowered. I didn't realize they needed full (mostly) sun. If I move it into sun, will I get flowers on it someday?
It may not be the sun. They need a little sun, but not typically full sun. This article can give you some possibilities as to why yours is not blooming:
https://www.gardeningknowhow.com/ornamental/shrubs/hydrangea/hydrangea-not-blooming.htm
Help. . . . my puppy has completely chewed all of the blooms off of my newly planted hydrangea. Nothing left but sticks. Any chance of saving it?
I'm afraid the best advice I can give is to wait. Since it is possible for these plants to come back from hard pruning (albeit delaying flowering), there is a chance that it may come back with some new growth. If not, you may need to get another and perhaps place some type of protective barrier around it to keep the dog away.