Square foot gardening definitely has advantages when it comes to early spring planting. Raised beds warm up quicker and with Mel's Mix (1/3 vermiculite, 1/3 peat and 1/3 compost), the mix stays light and fluffy and is never soggy. I use string to make my grids, but they have to be redone each year. Some people use wood lathe, lattice or other materials, but I prefer the string because when pulling up old plants, they have such a huge root ball, it seems it would be hard to pull them up with the lathe strips in place. It only takes about 5-10 minutes to do a bed. I have small nails driven in the top of the boards at 1" intervals on both sides and both ends. I tie the string at one end, stretch to opposite side, wrap 4-5 turns (no need to tie the string except first and last nails), go to the next nail & wrap, go across the box & wrap, until you are all finished. The string also keeps the cat out of the box.
This week I have gotten a lot of seeds started. I usually use the 72 cell mini greenhouse packs from Lowe's made by Ferry Morse, Ferry Morse Seed Co. I usually get 2-3 years out of the inserts, but I needed new ones. This year I couldn't find them, so I Googled greenhouse supplies & found a great site, Greenhouse Mega Store. They sell professional greenhouse supplies but also offer small order quantities. I still have several of the base trays, but needed new inserts. I was able to get a carton of 100 inserts (48 cells each insert) for $59.00. They have umpteen configurations for the trays. I ordered the 48 cell packs so I would have larger cells & better root development. They had super fast shipping too.
I used the end of one of my boxes to make a coldframe for the seeds I have already started. Night temps have been in the 40's & daytime temps have been in the 60's & 70's. If there is a chance of frost, I'll bring the trays in overnight, but they will be fine during the day. I raked the soil back so the trays would be lower than the surrounding soil level, then covered that part of the bed with an old white shower curtain. I pulled the corner back to check & it lets plenty of brightness in for germination & was cozy warm. When they start growing I will probably put a painter's plastic drop cloth over the bed. I have plenty of ventilation so they won't cook.