I never had a greenhouse until six or eight months ago, though I've wanted one since I was a kid. My girlfriend is impressively handy, and constructed our greenhouse mostly from parts we salvaged for free from someone who was getting rid of her greenhouse. (She says "we" built the greenhouse, but she was the brains of the operation, as well as most of the brawn.)
Anyhow, I use the greenhouse partly for propagation. I started many of my plants from leaves or cuttings. The adromischus at the far left is just a few months old, the pachyphytum in the middle, maybe 4-5 months. And the [echeveria?] at the far right is at least 8-9 months old.
For my small plants, I take those plastic nursery trays and fill them with 2" square pots. This seems the most efficient use of space. To the extent possible, I try to organize the flats by type--both for the sake of convenience and the ease of care. Here's a flat of sempervivums.
And here's a flat of (mostly) echeverias. As you can see from this picture and the previous one, very few of my plants are labeled. Only recently did I realize how darn convenient it is to know what things are and when you got them (and if there's room on the tag, where from). Nearly all of these echeverias here started last spring or summer from leaves. They grew a bit over summer and fall, did basically nothing over winter (well, some died), and now seem to be enjoying spring as much as I am.
Once, when I happened upon a small nursery that was going out of business, I found this hard plastic thing in a corner of a greenhouse, all mud-covered. They used it to grow agaves from seed, and sold it to me for $5. Now I use it as a place to grow my teensiest plants--the ones that aren't ready for 2" pots yet: a stray sempervivum baby that falls off, a wee kalanchoe sprout, etc. The little compartments are less than 1" square, so they hold quite a few plants and are great space savers. Anyone know where I could get another one? I've seen similar trays, but never made from hard plastic.
It is hard to overstate how much I love having a greenhouse. I'm still getting the hang of it, and have learned that for many succulents, the heat and moisture it traps are sub-ideal. I managed to cook--literally cook--a dozen or more plants, half of which are on the mend, and the other half of which now live in plant heaven. Now I keep a closer (near-daily) eye on it, leave the door open, and cut a big slit in one side of the plastic covering to help air circulation. I haven't had any more problems (knock on wood...), but I'd love to get tips from more experienced succ-ers on how you use your greenhouses.