I'm also in NYS, but usually a zone 5, and I use the same plant out dates that you suggested.

If it were me I wouldn't start hardening off seedlings with just two sets of leaves, and I don't count how many leaves, rather, how tall the seedlings are before I start hardening them off.

I want to set out seedlings that are about 6-9 inches tall and so start hardening them off at about that height and it takes me a full week to harden them off properly depending on the weather.

Have I ever set out plants with only two sets of leaves? Yes, I have, but only when there were special circumstances that dictated that I HAD to do that. Sigh.

Hope that helps.

Carolyn

I'm not disagreeing with the above but I don't think it has anything to do with the number of leaves. That is a secondary issue. The primary issues are the size/health of the plant and the weather 8-10 days prior to plant out date.

Depending on the variety and how the plants are grown one could easily have a 6-10" plant with only 2 sets of true leaves just as one could have a 4" plant with 3 sets.

Weather permitting your seedlings, IF they are at least 6" tall and healthy, should be ready to harden-off with care over the next week to 10 days and then go to the garden.

Dave