Is it true that crushed eggshells help strengthen your garden soil???

I have been adding eggshells to my compost for years. A couple of years ago I started grinding them up in my blender and sprinkling it around my tomatoes that were getting bloom rot, which I understand is caused by a lack of calcium in the soil. That seemed to help quite a bit.

Yes, the finer the better. They are also recommended for a compost bin. We do that all the time with excellent results.

absolutely..as does coffee grounds, fruit peelings, crumbled up dead leaves, grass clippings

Yes, crushed egg shells are good for your garden. You can take your egg shells, coffee ground and banana peels and put them in the blender and pour this around your plants. they will love you for it. I also save my egg shells for my chickens fore the calcium. I rinse them, let them dry and crush them up and mix them with their food-free calcium!

Yup. Epsom salt (magnesium) is also super important. Magnesium is the main building block of plant life.