I transplant into 3'x3' squares.

that should read 3"x3" ;)

3'x3'... that'll leave plenty of room to grow! ;)

Lets see... 3*3=9 9*65=585sqft

Should be fine, my house house is 1500 square feet, I should grow a few more! ;)

Now to figure out what to do with 9 times the footprint of the seedlings... I am thinking I may put them in the windows of my shed and get a remote temp sensor with an alarm... any idea what temp 1-2" petunia seedlings can handle safely?

Suaveant,

"...any idea what temp 1-2" petunia seedlings can handle safely?"

The Ball Culture Guide lists the "Growing On" temperature for Petunias as 55-58° F. That would be what commercial growers used in their greenhouses. They tend to run on the cool side for energy conservation, but maybe the plants like it, too.

MM

My petunia seedling are in 1 and a half inch x 2and a half inch six pak containers, one plant to a cell. They stay in them under lights and then outdoors to harden, planted out mid-May.