Montezuma's Free Range Manure is the brand of manure fertilizer that Eddy used to grow all the lawns in the Cul-de-Sac. It only appeared in "Keeping up with the Eds." According to Eddy, his father also uses it on his lawn as well. The manure itself comes in a very large-sized bag and grows grass to extraordinary heights. It seems to grow different types of plants depending on where it is placed. It can also grow fungi, as seen when Eddy placed a handful of it on Ed's shoe. It was originally meant only for Edd's lawn, but Eddy's idea was to throw it on every lawn so that they could mow the resulting grass down for cash. Ed managed to throw it all over the Cul-de-Sac with a shovel. This caused the entire area to be covered in extremely tall grass in a very short period of time.
- It only promoted growth in grass and fungus, as the trees and bushes were left unaffected by the manure.
- Even with the supreme height of the grass it was still fairly soft and pliable since Ed was capable of eating it. Despite this, it was sturdy enough to support the Eds' combined weight.
- Rolf's farm ground seems to be barren because nothing grew there.
- While it somehow made the grass taller, it seems to have different effects given the circumstances, as the fungus on Ed's foot is not replicated on the ground.
- Montezuma's Free Range Manure gets its name from Montezuma II, a famous Aztec Emperor who reigned when Mesoamerican indigenous peoples first encountered European conquerors.