How do I know when to start harvesting? Herbs.

Some herbs germinate and grow faster than others, but you can benefit by beginning harvests much earlier than you think.  Most herbs develop bushier growth when you harvest early — so as soon as you can trim a stem here or a leaf or two there, start enjoying herbs on your salads, or a handful in soups or sauces.  You’ll actually get more herbs in the long run if you start gently trimming them back early.