You have to use barriers to keep them away from pots. Make a cage of wire mesh, called "chickenwire", and put the pots in it.

Small garden areas can have a cage over them you remove to work.

I don't know how to keep them out of trees.

I cured my problem with old fashioned lead poisoning. It took several years to pare the population down to a workable head count.

Over winter squirrels girdled countless Japanese maple trees to get a bit of sugar. Not anymore.

The best way to get rid of squirrels is to use a hav-a-hart trap baited with peanut butter and then just drop the trap into a large tub of water. They don't hold their breath long. I use the hav-a hart trap so I can release curious cats (like my own).

But the water dip is fast, final, and as humane as I can manage in suburbia.

Here we use a combination of lead poisoning and live traps and swimming lessons. I have a little .410 that works well. The area is too populated to use a 22LR which would be my normal choice.