How effective is cow's blood as a deer deterent?

Question

In reading this thread I was curious about something I was told a while ago. A friend of mine said he was having issues with deer eating all of his plants. He said he was given advice to utilize dried cow's blood. To just sprinkle it onto the grass and it would deter the deer from coming onto his property. He said it worked well for him. He said a side benefit was that it fertilized his lawn, or at least made the grass very dark green in the process.

My question is, does this really work? If so, how long can you expect it to last? And lastly, is there any known reason for why this works?

Answer 1

There is a lot of anecdotal evidence on the web to suggest that blood-based repellents do work on deer. However, not everyone agrees. As deer are so olfactory-driven, it should last as long as the smell from the repellent lasts, and the deer aren't so hungry that your garden is their only option.

Due to the high nitrogen content in blood, this will indeed make plants grow faster and produce more foliage; however, it also can cause soil microorganism populations to skyrocket and then crash, so caution should be used about where its applied and to what degree. High-nitrogen-based chemicals can also "burn" foliage, so again - use caution.

Answer 2

Product called Plant-scyd is a mix of pig blood and a sticking agent. It generally lasts a season if not rained on too frequently.

It reeks

Deer will overcome aversions when starving. Deer will adapt to almost anything odd with time.

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Leaving a few dead deer carcases around is quite beneficial, and is a lot less work to apply. Note: Local wildlife officers may disapprove of this way of dealing with hoof-rats.

An 8 foot fence also works. An 8 foot fence that they can't see through is even better. An 8 foot fence with brush on the outside so they can't easily approach is even better. An 8 foot fence with an extension above that is difficult to see is the best.

Until the moose come.