When you say your trichs are a lime green color- are you sure you're looking at the right bits?
The little crystals on the calyxes and tiny bud leaves are trichomes. They should start off clear, then turn cloudy, then amber. When there are nearly all cloudy trichs, with very very few clear and some amber, your harvest window has begun.
You can toss a sheet over your plant to keep it from light frosts.