Some years back I tried to grow this chenopod, both in summer and winter and failed. But Craig Hepworth gets 8 foot tall plants with giant leaves, plus they freely self sow...I clearly did something wrong! I'm ordering seeds and will try again as the huge leaves dwarf those of the lambsquarter that reseed in one of my baby pool gardens.

http://en.wikipedia.org/wiki/Chenopodium_giganteum