This is somewhat of a general question, as it applies to several things I'm growing, but to be specific enough, I've chosen to ask it about one plant.
I'm in Zone 6 (−5°F, -20°C).
I started some Magellan Ivory zinnia seeds indoors under gro-lights. They outgrew the seed-starter pods, so I transplanted them into two-inch pots. They have three sets of true leaves, are becoming root bound and have begun to look unhealthy. The weather has been warm, and I've been hardening them off, so they're just about ready to go into the garden bed.
I've purchased the same seeds from this company and grown them successfully for years, and know they perform best in full sun. This year I'd like to put some in a new spot, but it may be too shady at the moment. It's fully shaded in the morning, then gets about three hours of mottled sun, followed by an hour of full sun, in the late afternoon. Within about three weeks, the sun will be there for six to eight hours per day, so I know they'll do well for months.
Can I risk planting them in a spot that isn't quite ideal yet, or do I need to transplant them into bigger pots and keep them in the sun for a while?