I just picked my first chamomile flowers of the year, which I'll be drying in order to use as a herbal tea.
It's best to pick them first thing in the morning, just after the flowers have opened. I tend to pick all that are open over the course of a few days to make sure I'm getting lovely fresh flowers - they taste better if you do it this way. For the amount I drink - no more than one cup a day on average - a few of these three day picking sessions are enough to see me through the winter until they start flowering again.
I was interested to see that the plants growing out in windier parts of our site are flowering sooner than those in more sheltered spots - the photos below show you the contrast. Or perhaps it's that the early flowering plants get the morning sun a little sooner than those that aren't flowering yet.
To process the flowers, first I put them in a colander and dip it in a bowl of cold water to let any chaff or insects float off. I give it a couple of rinses like this. I then let them air dry a little by laying them out on some paper, while I collect up more flowers over the course of a few days.
Once I've got a good sized batch, I dry them more thoroughly so they'll store without going mouldy. I do this by putting them on a baking tray at the bottom of the oven right after I've switched it off from cooking something else. I leave the door open a crack to let all that moisture escape. Otherwise, I'd heat the oven to 200 degrees C (392 degrees F) and would then turn it off and put the chamomile in. You leave them in until they crumble when you press them - this can take 4 hours or more.
And then I store it in an airtight jar to use throughout the following year. So long as you've thoroughly dried the flowers (so they crumble rather than squash), they keep really well. I'm still using mine from 10 months ago, but as you can see from the photo above, they've nearly all gone now, so I'm really pleased to be harvesting more!