I just happened on this video and like the cart.  I can appreciate what this guy said.  Every year gravity seems to get stronger.
https://www.youtube.com/watch?v=esGy37NNiGc

Thanks Tom, would be good if the lifting plate was closer to the ground cause as shown it is still 30cm above the floor in its minimal height and lifting the pot is necessary.
also I think much of the stress on my back atleast :) comes from lifting in the range o 0-30 cm above ground, after that the back can buffer the load between all vertebra.

who needs some Advil?

Bumping this post back up again. It had stuck in my head, and I recently saw something that might work well to build a similar cart.

Check out this lift from Harbor Freight. You could mount a deck on it pretty easy. I would also probably look at larger wheels, unless your greenhouse or plant area is paved. If you keep an eye on their sales, you can pick it up for about $70.

http://www.harborfreight.com/1500-lb-capacity-atvmotorcycle-lift-60536.html


Cliff

Big difference in price and function.

http://www.northerntool.com/shop/tools/product_200631993_200631993