Is it ok to cover outside plants with plastic to protect them from cold weather?
I would recommend cloth (sheets, blankets) over plastic. Plastic collects condensation, which can freeze during cold weather and cause harm to the plants.
Is it okay to place house plants and flowers in the garage when outside temps are under a freeze warning? Or should I bring them in?
The garage should be warm enough for a day or so. It will have stored its own heat that will keep it warmer than the outside.
When the temperature drops to freezing, how can you save your hanging baskets from freezing and what to do if you are not able to get them in? What should you do?
These artilces will help: https://www.gardeningknowhow.com/plant-problems/environmental/protect-plants-in-freeze.htm
The people next door built a fence and now my wife's garden floods. I was thinking of putting up a berm that drains to the alley about 20 feet next to the fence. Would this help?
Yes, placing a berm in the landscape can redirect drainage and reduce flooding. These articles will help:
What can I do to save my outdoor plants in a heat wave? Can they be placed into my basement for three days until it is over?
If they are in containers, you can easily move them to a shadier location. Unless you acclimate them, they may suffer from stress in the basement, going from one extreme to another, but if the temps are reasonably close to what they normally receive outdoors, this should be okay. You can also get some shade cloth for plants that cannot be moved. Also, make sure they are receiving plenty of water during heat waves/drought.
I live between Chicago and Indianapolis. We have a deck that faces the west. It stays extremely hot in the summer. I can't seem to find a plant that will survive this heat. I water everyday, but even the "decorative spike" in the middle of the plants looks bad. I currently have some colorful zinnias in the pot that seem to be doing OK. Any suggestions on which plants to buy for this situation next year? Thanks.
Perhaps, some of the suggestions in these articles will help you: https://www.gardeningknowhow.com/ornamental/flowers/fgen/full-sun-plants.htm
I live in the Northeast (Massachusetts). Weather has been hot and dry, and my lawn is all dried out and there are weeds throughout. Will it come back next year? Is there anything I can do to bring it back this year?
Grass naturally goes dormant when the weather gets dry. All you need to do to bring it back to green is to water it regularly. make sure it gets 2-3" of water a week.
Even if you do not water it, it will come back when its starts to rain more, whether that be this year or next.