During the growing season I'll start a lot of cuttings in the yard with just about anything. Plastic milk jugs with the cap left off make a great green house.
My only problem with that at this house is has very small back yard (corner house) and two 80 lb German Shepherds. Any milk jugs in their immediate area are just play toys. They have a 6'x24' kennel run but spend 95% of the time free in the yard. I even have to fence off my compost bins from them or they just thing it's a digging play pen.
In the front and side yard they know better then to go near any of the plantings. Of course when they are out side the fence I'm also there to give the evil eye.