The sunflowers should be planted in an area where it’s hard for a squirrel to reach. Once the sunflowers bloom, as in the leaves go yellow and the core, where the seeds are, turn dark brown, the squirrels try to reach it through the help of trees and fences. So the sunflowers should be planted in an area where they are hard to reach.
The sunflowers can also be surrounded with barbwire or chicken wire. It may be somewhat harmful and cruel for the animals, but to protect your sunflowers, this is a useful technique.
You can also cover your sunflowers with brown paper bags, nylon mesh and plastic bird netting. This lets the sunflowers enough space to breathe and bloom whilst protecting them from birds and squirrels and the damaging effects they leave.
Owning pets, like a cat or dog can also be very useful. As the smell of such animals tends to keep squirrels away, saving your sunflower seeds.
Another common method is spraying your sunflower seeds with hot seed spray that is readily available at any gardening store or nursery shops. An unusual method that has achieved success is the sprinkling of spices like red pepper and cinnamon around the plant that we are trying to protect. It was used to keep cats away but it works on Squirrels too!