Well, I just thought I'd throw this out there. It's not really a growing tip, just something to watch out for. When you recieve your pencil caps and plant them in the sand, they may look dim green, almost grayish. They probably won't perk up for many weeks if at all. But keep your eye on the surrounding sand bed. It seems that they use most of the engergy they have to send runners under the sand bed which will then sprout up as new "plants." So you'll have more than you know what to do with in no time! My personal experience entails having some of the pencil caps even engorged in cyano, then still popping up sprouts. Here's some pics to show the tale:
You can tell the difference in color in this photo from an "unhealthy" pencil cap that is growing sprouts right beside it that are nice dark green.
This is an overall shot, but you can see quite a few sprouts sticking their heads up.
I've even pulled pencil caps out w/ a few sprouts and found that their runners are up to 4" away. These things work fast! So, moral of the story, don't throw your pencil caps if they don't look good, they're probably just reproducing! Good luck.