Don't mean to be cocky - but it all depends how much space under the lights you have and how much a "bunch" is. If you have two 4ft. fluorescent lamps with two bulbs each - that will hold four standard trays of seedlings. If you are potting them up to traditional 6 packs thats 48 cells per tray which is 192 plants. I use larger pots so can only fit 32 plants per tray, but there is enough room for them to grow quite a bit larger than what is typically purchased at the nurseries. As far as height goes, its only limited by how you hang your lights.

docmom,
Everyone on the Hummingbird Forum raves about Lady in Red as a favorite of hummingbirds. I grew a shorter Salvia coccinea last year and it worked well. I'm in the same zone as yours and May 15 is the average last frost date. 60 days under the lights ought to make for some pretty tall plants. It shouldn't hurt to cut them back later and let them regrow. The cuttings would probably root well if wanted.

Thanks for the replies. I have three 4-foot shelves, but I also planted some coleus and tropical milkweed that will also need to stay under the lights. I guess I'll pot them up when necessary and start giving them away or putting them out on the back porch if I run out of room. It depends on what kind of germination I get from the coleus and milkweed. Hopefully things will grow slowly enough that we'll be done with hard freezes in time to start the hardening off process.

Martha

I'm about to start seed of this variety of S. coccinea under lights (having a cool basement and bright LED fixtures will hopefully keep plants compact until I can get them out into the cold frame in May).

The advice given to trim back any leggy seedlings grown under fluorescents is good. The plants should really take off once warm settled weather arrives.*

*as I speak, a drenching cold rain has been replaced by light snow, and the garden is at its most desolate-looking. The answer to that is...start more seed!

I started these seeds indoors, too and, being this is my first time starting things in doors I'm sure I'm making some "errors" but I do think these ones have started for me, albeit small. Good information here!

If they grow too tall pinch them back. They will bush out nicely. Salvias do better, bloom longer with pinching.