1. Variety: Different varieties ripen at different times. Some early, some mid and some late. To make it easy Goldings and Fuggle are early, First Gold and Challenger are Mid, Cascade are late.
2. Location: Whilst you may have an early variety if you don't live in the South, you may potentially be picking your hops up to a week later. Good position, soil and drainage will also have an effect
3. Smell: Do this over a couple of days. Take a cone and roll it between your palms. Cup your hands with the cone inside and inhale. You will notice a huge difference in aroma over just a few days if the weather has been good.
3. Petals: If the petals on the cone are starting to dry and open up they're nearly there. A tightly packed cone is not ready.
4. Lupulin: The yellow sticky stuff. When ripe they will have an abundance of this at the lower end of the petals.
5. Seeds: Pull a cone apart and at the end of the petal near the stalk you will find the seeds. If they are going brown or black, they're ready. A soft green seed is not.
6. Still not sure: Take a cone by the stalk and gently bash the tip into your palm. If it easily falls apart and the petals float away its ready.
Remember an over ripe hop is better than an under ripe one.
Happy picking.
At this rate, I will be testing the 10 cones I have before I can actually brew with them, the system seems flawed to me.