I planted many geraniums in red and white. Some have done really well while others close by have done badly and in some cases died. The white ones did worse than the reds. They are in a south facing bank, mostly in a compost soil mix.
Watering is usually the issue with Geranium issues.
Also deadheading the spent blossoms is the best way to keep the plants fresh and blooming throughout the season.
Here is a link to refresh you on the care requirements.
https://www.gardeningknowhow.com/ornamental/flowers/geranium/geranium-care.htm
Is there a way to simply cut back the geraniums by 1/3 or so, leaving them in their original pots and storing them in a heated, lighted garage? If so, how often should I water them? Thank you.
Yes, pruning them back usually helps reduce shock from bringing it indoors. This article will provide additional information for overwintering these plants: https://www.gardeningknowhow.com/ornamental/flowers/geranium/how-to-save-geraniums-over-the-winter.htm
Some of my geraniums have scale like spots on the underside of the leaves. The leaves turn yellow.
Your plants could have a pest issue or Virticillium can attack geraniums.
In the case of verticillium the plant would need to be disposed of.
Likely the plant just needs some watering adjustment and a Neem Oil treatment generally takes care of most insects or fungus.
Here are some links for you.
https://www.gardeningknowhow.com/ornamental/flowers/geranium/geranium-yellow-leaves.htm
https://www.gardeningknowhow.com/plant-problems/disease/verticillium-wilt-treatment.htm
https://www.gardeningknowhow.com/plant-problems/pests/pesticides/neem-oil-uses.htm
I have a well pit that stores potatoes over winter beautifully but is too damp for winter squash. The squash just rots. Would this also be too humid to store geraniums in either pots or bare roots? I do not have a basement. Thank you.
The humidity may be to much for the Geraniums also, you may lose them to mold if the air is to humid.
You can always just cut back and put in a location indoors for the winter.
Here is a link with wintering care.
How can I save my garden geraniums over the winter? What is the procedure?
You can actually winter over your Geraniums several different ways.
This article will help you.
The article says to hang the geraniums upside down, but doesn't give a clue as to how to do that. What is the best way? String? Wire? From a clothes line? Cup holder under shelf? Ideas/solutions, please. Thank you.
This article will answer your question: http://homeguides.sfgate.com/hang-geraniums-over-winter-garage-104713.html
When should I take geranium cuttings?
You can really take cuttings and propagate geraniums any time of year.
The healthiest part of the plant is near the tips so taking short cuttings is a good technique.