To supplement what Mexicanpeeler has mentioned you also want to harvest as close to a full moon as possible. Of course this is true for almost all gardening unless you want crystals or shellbugs.
Just watch... these, along with the other elemental ores, are about to become as worthless as crystals. The market is so oversaturated and people are slashing prices. Soon, you 'll be able to pick up any of them for less than 10,000. Watch. Sellers are inherently stupid and will slash prices to nil before they learn an ounce of patience.
If people keep underselling these, and everything else, eventually they will be worthless.
This is what happens when children get impatient and want gil now, and sell for less. It will lead into another market crash, just watch.
LOL GSers nothing, it's the ppl that makes the Ore, thru growing it in the Mog House. Takes awhile to grow out, either that or going out to Ifrit's Cauldon and mining it. Which is a pain in the butt.