Thanks calistoga for the advice, I will leave them in there cells a little longer, but remove them from the bottom heat. It shouldn't be to hard to cut there cells away from the rest of the seed flat. I will just have to be careful not to jar the adjacent cells to hard. As for damping off, I am using an all natural product called Damp Aid. I mixed it into the growing medium before I sowed in the seed, and I also use it as a top dressing after watering. It has a wonderful sent to it, and so far seems to be working well. I also have good air circulation around the flat, the only draw back is that my soil drys out much faster so I really have to keep an eye on them. Thanks again for your advice, it is greatly appreciated!

My experience flies in the face of everything considered 'right' about growing avocado trees. For one thing, I never bother doing the toothpick thing--I just drop them in a bowl of water and wait. Once they crack and there's growth showing, off they go to a pot filled with potting soil--in full sun. Or not. Sometimes I just stick them in the ground. Do they grow? Why, yes, they do! It's hard to tell from this picture, but the avocado tree is about five feet tall; I have pics of it when it was a wee seedling back in 2009--in a pot in full sun. :) Do note that I'm in the San Gabriel Valley area of Los Angeles. We have no winter to speak of. My entire backyard is in full sun all day--full, HOT sun. We've been right at 100 for the last few days, and we broke numerous records this 'winter' with 90+ degree days.

I let each individual plant tell me. if its late season (Late Oct or early Nov for me) and the bottom leaves are yellowing then I should reduce watering to the level of maintaining a low amount of moisture in the soil. I run my finger through the top 1 or 2 inches of soil and if the soil is darker than the top crust and my finger gets dirty (more than just dusty) I'll wait a week to water. I could use a moisture meter to see the % but have always just used dead reckoning. If the tips and recent season green growth are feeling soft or wrinkled I will give that plant a little more this week and revisit in a week. I also watch for warm spells since it seems most of mine only partially hibernate and the greenhouse can go over 90 degrees if its not vented. I typically go into the greenhouse every week to police up dropped leaves and make sure things look good. I randomly squeeze branches, pull off any dead material such as shriveling up inflos, "claws" that didnt develop, and feel for softness and look for other danger items. For me it's only about a half hour of time to handle my collection (never counted and don't plan to but would say 30-50). IMO having a good soil mix and plants well supplied with nutrients over the growing season can help by being a little more forgiving one way or the other. Its really hard to use a sequence of care that isn't specific to your local variables. I hope this helps and you experiment and find the method that works best for your plant(s).

At this point only knowing what you posted I would recommend planting about 2ft apart. If you have the space do it in a triangle shape. In a few years you might have to separate them but you have sandy soil so it should be easy enough to do just before they come out of hibernation.