I agree that individual plant or bed-sized fences and cages to protect the food crops are Worth trying to discourage any kind of pests. Exclusion if successful can help to TRAIN them to give up and seek target elsewhere. Motion activated lights and alarm can also discourage especially when deployed early. Security videos help to identify animals and birds.
In my area, what we have are grey tree squirrels with big fluffy tails. They live in trees and tend to prefer nuts and grains — they are particularly bad when trying to grow corn. Raccoons are also corn marauders. I have heard that they can also be bad for tomatoes but in my garden it’s chipmunks that tend to go after my tomatoes, never squirrels.
The broccoli and Brussels are overwhelmingly attacked by groundHOG/woodchuck and Brussels by chipmunks.
So I’m wondering if your “squirrels” are ground squirrels? We don’t have those here so my knowledge and advice will be less relevant.
With regard to tomatoes and chipmunks in general, I believe providing a ready source of water away from the garden goes a long way if they are after the tomatoes for the moisture. (I’ve heard this about tree squirrels and birds as well). However, with chipmunks, they have a way of stuffing their cheek pouches and then stashing their hoard. This tendency to take more than they need to satisfy immediate hunger makes them particularly pesky — they are repeat offenders as well. These traits are also shared by groundHOGS and raccoons. Once they find your garden, they WILL return.
I have had some limited success with low power electric fence that is just enough to zing them. Ultimately, I have had to use traps for persistent thieves.
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