My mother planted chionodoxa and scilla in the lawn, and the squirrels dug them up and hid them elsewhere. Then forgot about them. So they came up in other random parts of the lawn. Squirrel gardeners!
I had a coworker who laid chicken wire over the bulbs. The chipmunks just dug down outside the chicken wire and tunneled over and got them anyway.
When I planted bulbs in '09, I planted them with a bit of used, strained cat litter. The major contaminants weren't there, but there was enough cat pee residue to keep the squirrels away. And the litter itself (World's Best Cat Litter), is made of corn, so it's essentially mulch.
I put clean soil on top of everything, so my neighbors didn't have to deal with eau d'cat pee when they walked by. The squirrels didn't touch any of the bulbs the first winter and only dug up a few last winter. I may need to retreat them this fall. Luckily I have an unending supply of predator-scented bulb planting mulch.
I live in a former pecan orchard and have squirrels living in my attic, and find they don't mess with crocus tommasinianus, grape hyacinth, ipheion, or most daffodils. Maybe they're just too busy taking a single bite out of each unripe tomato I grow.
First time I put down Deer Scram, I thought it smelled fabulously like pizza (it has oregano in it). The next day I kept looking for the rotting body of an animal and finally realized it was the repellent.
> just too busy taking a single bite out of each unripe tomato I grow.
ohhhhh I hate that.
I can vouch for this stuff: [link]
We have squirrel gangs that wage food fights for sport. It scares them away. Except for the tomatoes.
One year we had planted dozens of Allium Gladiator, which as an onion is supposedly yucky and critter proof. Someone kept digging them up, these tennis ball sized bulbs, gnawing on them, declaring them disgusting, and tossing them aside. We'd pop them back in. Someone would dig them up again and gnaw a little more. This went on for several days before the squirrels got the right memo out to the neighborhood.
that's two votes for the Scram! It seriously does work. Once a month. Deer, rabbits, groundhogs, squirrels. (the smell does dissipate, and I did put it down rather heavily).
also, I had a neighbor who swore by coyote pee. Which you can get on the interwebs. because you can get everything on the interwebs.
eta: this isn't a dare for an ita link. this is a bonafide gardening post.
There is a freakishly huge grasshopper down here that loves amaryllis, but nothing else. I left one in a pot in the yard for 2 weeks when we moved down here and they ate the entire bulb. (I hate the lubbers - they are 3 inches long and like some sort of prehistoric nightmare bug: [link] )