My heart goes out to you. I was out earlier this morning and found an entire bed of over 100 bearded iris with half of them sticking out of the ground sideways and the other half uprooted again and partially dragged off. One problem, this must have happened those few days we had temps around 40 last week and I didn't catch it so now the ground is frozen again and the rhizomes can't be moved without a chisel or jack hammer. The damage these critters have done to literally thousands and thousands of dollars of woodland species of plants I planted over here would make you go out of your mind. What they did to my entire bog of outdoor CPs last fall was the final straw.
You have a few choices.
You can add a kiddie sandbox somewhere on your property that you put nice loose soil in for the squirrels to do their thing in. The squirrels will use it and it may distract them for a while but it isn't a long term solution. The other problem with the sand box is that feral and stray cats will start using it to do their thing sooner or later. There are those who swear by this. Personally, I don't want to look at a squirrel dirt box in my yard and I am not going to put up with stray or feral cats on my property.
You can try using chili powder or similar. This can work for a little bit, at least until it rains. If you do not reapply your red cayenne or chili pepper immediately after it rains, the squirrels will be right there the minute you forget and they will rip the crap out of your plants. There are many people who swear by using these types of products. I bought them in bulk at Sam's club and felt as if I should have owned stock in the companies that sold these powdered peppers and ultimately, the squirrels seized upon any opportunity and still trashed plants. I don't think these work and they are a total waste of money and your energy applying them EVERY single day sometimes 2x and 3x.
Plastic owls on stakes provide relief for all of one week. I even bought the one with the head that swirls around with the glowing eyes. I had metal stakes strategically placed in and around my plants and I propped old hooter up and I religiously moved him from stake to stake in and around the area I wanted protected. Sooner or later the squirrels figure it out and they are back to tearing the crap out of your plants as if there is no tomorrow.
There are lifelike blow up snakes that you can purchase to place on the ground. These work for a few days. They have a tendency of getting blown around in the wind though and you have to stake them well. The minute you stake them well, you can't move them around and that is when the squirrels will know it is fake and one day you will walk out by your plants and see the squirrels doing their thing with the fake snake flopping around on the ground in a breeze. They do come in a very attractive color array. You can have nice bright orange with purple spots as well as the more life like looking snakes. Don't bother, I've tried them both. Both are equally ineffective.
Mothballs will work. I can't recommend this as they look like nice big peppermint jaw breakers to children and furthermore they are highly toxic and will leech down into the potting medium of your soil. If I am not mistaken, they are also carcinogenic.
I have entire shelves in my garage that have very expensive products that allegedly would deter squirrels and deer and rabbits. No sense providing you with the names of these products as none of them work. NONE OF THEM WORK. They all are a big huge waste of your hard earned money.
Poisons work. I refuse to use poisons as they are non discriminatory and squirrels are part of the food chain. No sense poisoning a squirrel only to find out one of my turkey vultures ate it a few days later. The issue that concerns me the most with the use of poisons is that the death is horrible and very slow for the animal. It's inhumane in my book. I don't feel the use of poisons is ethical. The animal is only doing what animals do to survive and we really need to separate the behavior from the critter. God forbid a child got into poison too.
You can run out your door charging the squirrels wildly flapping your arms while screaming obscenities. I’ve done this before. Make sure the door is unlocked before you run at the squirrels in a rage so you don’t lock yourself out- been there done that. Another tip, make sure you are dressed before running out to charge the squirrels or your neighbors will think you are insane. You will feel better as the squirrels will take off but they will just wait until you leave for work to come back and do their dirty work so this doesn’t really work all that well now does it? Large dogs work too. You open up the door and yell sic em and watch your dogs shoot off in three different directions. Then you spend a few hours gathering up your dogs from the neighborhood because they are freeeeeeeeeeeeeeeeeeee! The squirrels will take off the first few times you let the dogs out but after a while they become desensitized and just run for higher branches to wait until the dogs are brought back in the house so they can come back down and destroy your plants.
So, what works? Build a greenhouse on your property and place your plant in the greenhouse. No money for this? Don't feel bad, me either.
You can get a HavAHart trap.
http://www.doyourownpestcontrol.com/SPEC/pick-havahartsq1.htm
Do not buy the new squirrel repellant that HavAHart is marketing because it doesn't work- I own it... I know. Stick to the trap and you'll do fine. Bait the trap and you should have your squirrel. Now that you have the little squirrel face in your trap you might as well shoot him or call animal control to come and pick him up to humanely destroy him as to take him for a drive in the country is a death sentence anyway as they are territorial. Seriously, they will not be able to live if you dump them near a farm or on a country road somewhere as they generally die from injuries sustained from other squirrels in the area or from starvation. If you go and dump the animal in another residential area, it runs into the same territorial issues and additionally somebody else inherits your problem and that isn't too neighborly.
It is legal to discharge here. One problem is that I couldn't bear to kill squirrel faces so I now have a staked bog that has chicken wire all around it. The top has fruit tree netting on it. This keeps the squirrels and the feral/stray cats out. Extremely unattractive, but this is the only line of defense I have found that works other than shooting them with a .22. Following along this concept line, you could create a frame out of 2x2s and you could use a staple gun and attach chicken wire and create a nice little wire cloche to go over the top of your plant and I would think this would work... unless of course your squirrels organize and go at the enclosure as a team to knock it over to get at your plant and I wouldn't put anything past squirrels these days. I'm going to have to do something myself here real soon as I have some larger pots the critters are already eyeing and I see trouble on the horizon. Last year I saw a big old tom cat balancing in a tri pod position over one of my planters and he took a dump. That planter didn't have any plants in it at the time but it will this year. Feral and stray cats are picked up by animal control and are humanely destroyed around here. The tom cat is no more. That still leaves squirrels though. If you are having a problem this early in the year, you should be pulling your hair out by fall if you don’t come up with some way to protect your plant.
Best wishes to you and I truly mean it. If I had it in me to shoot them, I would in a heart beat as a .22 is pretty quiet and the death is quick. Should you find anything that works that I haven’t tried, please share with me.