I live in Sacramento, CA (zone 9b). Winters are mild. Dec/Jan average temps range from 55F - 40F during day/night. However, depending on year, we can get some frost from mid Dec - mid Jan. I would like to start seedlings (marigolds, zinnias, petunias, violas, salvias, vincas, pansies, snapdragons) around early/mid Jan for transplanting by March.
Right now, I am using two seed trays and a Philzon grow light. Results are very good. However, space is limited and I foresee using about 6 seed trays per year to cover all the flowers for the year for front/back garden.
I was thinking of building a small cold frame in my backyard, and putting the seed trays in there in early/mid Jan for sprouting / growing. Is it a good idea and will it work?
Something like this: https://www.pinterest.com/pin/525091637802640544/?nic=1