This post isn't so much a how-to on starting seeds, but some ideas on the types of containers you can consider. I'm a big fan of re-using and re-purposing, so I have a few suggestions for you!
When looking for containers to start my seeds, I prefer to use materials that can readily break down and add organic matter to the soil. You can purchase peat pots or peat pellets at the garden centre if you want to go that route. Or, you can use items you already have around the house. Like ...
2. Egg cartons. The cardboard kind, not styrofoam. Remove the lid and add soil to the individual compartments. Once the seedlings are ready to transplant to the garden, cut or tear the sections apart.
3. Empty toilet paper rolls. Cut four slits approximately 1 inch, evenly spaced, on one end. Fold in the resulting four tabs to create a bottom.
Any of these options will hold your soil and seeds and can be planted directly into your garden when the time is right. You won't disturb delicate roots, your seedlings will have an easy and smooth move, and the containers will slowly break down into the soil.
Of course you can also use things like empty yogurt or pudding containers. You will need to carefully remove seedlings from these containers to transplant, so it's a little more touchy, but the containers work great. Just try not to disturb the roots too much. Either gently squeeze the sides, while holding the seedling close to the soil and pulling gently (upside down), or use scissors or garden shears to cut the container away.
Especially if you are using biodegradable materials, you will need a tray of some sort to keep the surface underneath the pots dry and clean. Purchased kits will come with a covered tray, but have a look around and see what you have already. And old cake pan, or even foil pie trays work great. How about clamshell containers from the bakery? Built in cover to keep in the humidity! If you have styrofoam egg cartons, use those to hold your eggshell plants. If don't have anything to hand to keep your egg shell planters upright, check out your local dollar store. You should be able to find a variety of disposable foil trays and pans there for $1 - $2 each, or even less. Pack your shells or other containers in snuggly. I picked up a super, covered, foil casserole dish for $1.25 at my dollar store. Having a cover over your seeds aids in keeping the soil moist and the temperature warm enough for germination. You can remove the cover once the seedlings are an inch or so tall. If your tray/pan/etc. doesn't have a clear lid, cover your seed containers with plastic wrap.
What do you think? Do you start seeds indoors? What kids of containers have you used?