I recently just invested a large amount of time and money to plant over 1300 bulbs (tulips, daffodils, crocus, chinodoxa, species tulips, snow drops, you name it!) in my garden beds. As we have a large squirrel and rabbit population near my house, I'd read that blood meal was an effective deterrent to them digging up bulbs.

I did not mix the blood meal in with all the soil. Instead, I used the "lasagna layering" approach for my beds and I sprinkled a layer of blood meal over the deepest layer of bulbs (tulips and daffodils) after I'd put in about 2 inches of garden soil on top of them. Then I planted the rest of the bulbs and sprinkled another layer of blood meal on top of the soil and then added a thick layer of Scott's Nature Scapes Color Enhanced Mulch (about 2-3 inches). I'm now reading that blood meal adds a lot of nitrogen to the soil and that too much could cause the bulbs to not flower. I can't do anything about the blood meal down deep in the soil (but it was less than a half cup spread over a 4 x 8, 1.5 foot deep bed and an even smaller amount in another bed), however I am concerned that the blood meal on the surface may also add to the nitrogen problem and seep down into the soil. We've had some heavy rains today, and I've watered daily since I put the blood meal and mulch down last week.

Is there a risk that I've just created a no flower situation come spring? Is there any additive (like Bone Meal) I can also add on top of the soil or should I peel back the layers of mulch and try to scrape away the blood meal that hasn't already sunk down into the soil with watering and heavy rains? Am I worried over nothing?

First, blood meal is only effective as a deterrent to critters if it remains dry - the suggestion is to place it around in small containers and replace as necessary after rains. It is almost entirely soluble and when it comes into contact with moist soil or when watered in, it will break down rapidly into its elemental forms. Some rodents (squirrels in particular) also seem to develop a taste for blood meal so its effectiveness as a deterrent is questionable. It is also likely to draw the attention of dogs, raccoons or other carnivores. Caging the bulbs would be a much better method.

There IS a risk of blood meal 'burning' plants if applied excessively or if it comes into direct contact with plant roots. And while it does carry relatively high levels of nitrogen for an organic product, it is not very long lasting and is pretty much fully dissipated in 3-4 months. Nitrogen is required for good bulb health - it is only excessive amounts that can encourage foliar production at the expense of flowers but 1/2 cup is not an overly excessive amount over a 32 square foot area. FWIW, blood meal is a typical ingredient in organic bulb fertlizers as well as an often recommended amendment for bulb planting, if used in moderation.

Thanks so much for all your feedback, by the way!!

I've had good luck with laying sections of chicken wire flat on the ground. Plants grow through and cover the wire and racoons/skunks don't dig up plants.

As a FYI - I used what red pepper I had in the kitchen the other day and the squirrels avoided those sections of the beds. Anywhere there was NOT cayenne or red pepper flakes, however, were clearly "explored" by the squirrels. Time to head to Costco and buy the red pepper in bulk!!

If a squirrel has the intention to dig, nothing short of removing its claws, will prevent it. The chicken wire, if its small enough, but large enough to allow the foliage to come through it, can work if the squirrel has a time to get by it. Sensing the soil there is soft from digging, the wire will move easily with the animals digging and probably only put up a barrier for a short time.
Put a preying bird ontop of the ground, he might take a look and run for cover....or he may laugh at the silliness of the planter to think he can be fooled so easy and take a bite out of it as well. A snake of the same intent will probably leave the animal guffawing and rolling on the ground in hysterics. But, what the hey, it can be tried.
They sell plastic owls in stores....but move it around, the squirrel might be fooled once.....shame on him.....
but fooled twice...shame on you for not thinking of it sooner.