From the directions on the website on one of the seed packets, linked, it looks like I need:

http://www.swallowtailgardenseeds.com/tips_lists/startingyourseeds.html#gsc.tab=0

Scott's Supersoil Potting soil

And the following three things:

They recommend florescent lighting - won't LED be much more efficient?

If the above components look about right, could you please specify what kind of lighting to use?

tanyuu - Thank you very much for the advice, apologies for not getting back to you sooner. Re potting soil - we purchased a few bags of Miracle Grow and some vermiculite; does that sound ok?

We're going with fluorescent HO T5s vs. LEDs. We can easily hang from the ceiling (all kinds of hooks in place) and DH has plans to hang the fixtures on a chain, so that I can easily raise/lower the lights, just as you suggested. Point taken about larger and more mature plants requiring more light; I hadn't thought about that.

Sorry about the delay in getting back with you!

As for the miracle grow + vermiculite, I myself would save that for when you're potting up larger plants. Miracle grow (i'm assuming potting mix) has a lot of additives (like fertilizer) meant for older plants, so they generally hurt seedlings. Even if you have vermiculite, I wouldn't chance it. Get some seed starter soil, or if you're in a pinch, organic potting soil. The key here is the soil texture being light enough for those seedlings to poke through.

I can't give much more advice on lighting beyond what I've already given, but it sounds like you got a good set-up going! Generally aim for a 2-4ish inch height between the seedlings and the lights, though you might have to adjust if the amount of heat/light your lights give is higher. The amount of light shouldn't be too much of a problem if you're just starting seeds early to later transplant outside. You can always buy more lights later!

Also, depending on the sort of air flow you have in the greenhouse, I'd recommend an osculating fan so the seedlings build up strength. Just use a junky/cheap one you might have around that you don't mind having in the greenhouse, nothing fancy! This is my main problem, since my seeds are on shelves. The seedlings just flop all over the place when I put them outside!

Since you're dealing with older seeds, you generally can probably get away with putting 2-5 seeds to a cell depending on the type and size of seed, as some seeds are still viable even after years of storage.

As another spammy side note: http://tomclothier.hort.net/index.html this site is the best for finding what temperatures/amount of light/etc you need to start most types of flower seeds. Some seeds actually need cooler or warmer temperatures or darkness in order to germinate!

Hope things are going well!

Hi tanyuu! Somehow I missed this, glad I checked in on the thread, thanks so much for your help. I did end up researching and buying seed starting soil. DH added a 4gang outlet and the lights are up. They're on a timer for 15 hours/day and we have already a handful of seedlings poking up. (Though I just planted Wednesday?) Note I did soak some of the seeds for almost 24 hours, and quite possibly the heat from the lights is helping too.

The heating mats are due tomorrow. Thank you for the advice about the oscillating fan; we will add to the setup. I had read about fans but hadn't yet figured out their purpose.

I don't see your links as spammy at all. Thank you for the tomclothier link!!! What a great resource. I just read up on damping off and remembered I forgot to add the fungicide when I planted. Will try to remember for the next watering. I do have 2 more flats wrapped in a dark garbage bag on top of the fridge (did follow the directions re light vs. darkness for germination).

I planted about half of the wonderful heirloom tomatoes, bell peppers and strawberry seed I purchased. Where do you keep the seed you plan on using again?

Here are some pictures of what we have in place.

(Yes it's snowing outside, again).

The humidity domes seem to be working well, but I'm definitely noticing that the condensation is around the outer edges (lights may be drying up the plants closest).

I thought that some of these looked too dry so watered (from the roots up, briefly, then let drain):

And look!

Wow, you have a nice setup! I hope all goes well. The fans should help strengthen plant stems as well as help prevent damping off disease, which I always have problems with because I overwater everything.

When it comes to storage, I've found the best place is in a plastic bag in the fridge.