I'm a first-time onion grower. In the spring, I bought a bag of onion sets which I planted in the garden. Now, 3 months later, I've pulled out a few small onions (about 2 inches in diameter), and left them out to dry. They've been out for maybe 2 weeks and I noticed that they are all turning a light green color. What am I doing wrong? Can I still eat them? I've got many more onions left in my garden that I haven't pulled & I'd like to make sure they stay white.