"The first of his green plays, is up 147% since April and "could still double," Cramer said."

"Foster Wheeler (FWLT) is up 99% since April, Cramer said, noting it's worth owning more for its infrastructure component than for its green component."

"BorgWarner (BWA) is up 38% since April and still has legs, Cramer continued."

"OM Group (OMG) has been "the dog of the green group," he said. It went down 5% since April because of uncertainties regarding its pricing. And although its recent quarter was "really good," he said he's not going to be too aggressive in recommending it."

"First Solar (FSLR), up 170% since April, reports tomorrow, with Cramer expecting analysts to raise estimates. Cramer said he would wait for it to report before buying, because it's had such a big run."

"Fuel-Tech (FTEK) is up 35.3% since April, Cramer said. Instead of getting out of OMG, Cramer said he would rather ring the register on FTEK."

"The one stock out of his green group that he still regards as a bargain is MEMC (WFR) even though it is up 19.8% since April. This company has the silicon that solar companies are addicted to. "The risk/reward is too good to give up," Cramer said."

"Finally, he said, Tetra Tech (TTEK), up 16.9% since April, could also do better."