Comments from Lowe's website:

"Not as described. This pump would only work under siphon conditions i.e. if the water source was far higher than the drainage location. I returned it and purchased a higher quality pump that would pump up a few feet."

and...

"Piece of junk! Operates erratically. I've tried to contact the maker twice but they've never responded. The hose that comes with it collapses from the suction. You have to put vegetable oil (or mineral oil) in the thing everytime you use it. This thing is definitely going back!"

Your problem with such an arrangement as you describe is loss of head pressure/flow trying to get water to your misters. In order to maintain the pressure you need to operate the misters so they perform up-to-spec, you'd need a much larger, heavier-duty pump...that'd cost hundreds. Most misting heads need 30-50psi to operate properly...the more, the better. The best you'd get with that pump from Lowe's is maybe a bit of dribbling.

I wouldn't know how to do it, but it may be possible to run a water line from your house to a pressure tank, and have the pressure tank move the water from your barrel. But this is additional expense, and I'm not sure it's worth it.

-Bruce

I have a similar pump thats 12 volt. I use it to water by berry bushes. It will water up hill with 100ft of length with no problem. This pump is very comparible to the pump I have, its just 110 instead of 12volt. Im not saying it will for sure do this task,but I bet it would based on what my other one will do. Im not spending 400 dollars on a pump for a hobby greenhouse. Now Im not sure how many heads it would pump water through. If it doesnt work, I can take it back to lowes. I do need some type of watering setup though. I do appreciate your feedback though. I really do like my 12 volt pump and have been very happy with it.

Be sure you're comparing apples with apples with your 12V pump. You say it moves water 100 feet uphill with no problem. But is that water "spraying out of heads," or is it "pulsing out of the end of a hose," or is it "seeping out of a soaker hose?" Only you can answer this.

As an experiment, hold the end of your hose you use to water your berry bushes up six to eight feet -- the distance of head you'd have to have in your gh from the bottom of your rain barrel to the rafters where you'd mount your misters. I suspect you'll find that your small pump doesn't have the horsepower to achieve any sort of pressure at that height.

-Bruce

What does your pump specification plate say?
If the maximum head is somewhere around 130ft(40m)it should be ok with 50psi misters.

One things I believe that I have going it with my greenhouse design the pump it only delivering water at a lift of only 4ft. Im going to plumb the misting system then use my 12 volt pump to attempt the feat, then determine if the 110 volt pump will duplicate the watering job.

A 4ft head is well under 2psi.
The very lowest rated nozzles are around 15-30psi.