Tropicals & Tender Perennials: Hardening off my baby brug seedlings?, 1 by andycdn

andycdn wrote:
My babies are now around 18" in 4" or 6" pots. Our night temps are still in the 9-10C range, with days ranging from 18 to 24C. Is this too cold to start hardening off? What about getting them used to direct sun after full-day window sun?

My plan is to start putting them outside on warm days, in the shade but allowing an hour or two of direct sun at first, then lengthening that time. Bringing them in at night until the temps are __ what temp? How soon can they tolerate a full day of sun?