I live in southeast Massachusetts. I started hardening off my seedlings this week, going from 2 hours to 3 to 5, on a porch that gets dappled afternoon sun through the porch railing. The daytime temps have been in the low 60s. While the stems and branches are firm and robust, the leaves get droopy outside. I've also had a few leaf tips go dark green and curly. What am I doing wrong?