Do I need to cut back my perennials?
Some perennials benefit from being cut back, but not all of them. Which perennials do you have?
I wanted to know what is the best time of the year to trim bushes, spring or late fall? Why?
It really depends on the bushes and if they are bushes that bloom from new growth or old growth. Which plant do you wish to trim? We can give you more precise directions on how to trim it if you let us know.
Do any types of flowers grow after cutting?
Yes, there are several kinds that do. This is a practice called deadheading. You take off the first batch of flowers and the plant will grow a second batch. Here is more information: https://www.gardeningknowhow.com/ornamental/flowers/fgen/deadheading-flowers.htm
It should be set in teh center in the soil.
Since this was the first freeze that I can remember in Texas, when and how do I prune my sago palms, pony tail palms, avacado tree and date palms?
This article should help with that: https://www.gardeningknowhow.com/plant-problems/environmental/tips-for-saving-cold-damaged-plants.htm
I would like to confirm once and for all how much to prune below fireblight infection. I see 8 to 12 inches, at least 9 inches, etc. I think it's really supposed to be 12 inches and no less.
Yes, most resources do specify cutting back branches 8-12 inches from the canker margin, or affected area. However, I recommend 12 inches, as the canker margins are not always well defined and at least this way, you're more likely to get all of the infected area. Always better to be on the safe side.
What plants can I pinch out?
You can pinch back nearly any type of plant such as annual flowers, vegetables, herbs and late-blooming perennials. Here is an article that you may find helpful: https://www.gardeningknowhow.com/garden-how-to/info/pinching-plant.htm