How do freezing temperatures effect herbs?

When is it too late to harvest thyme, rosemary, and lemon grass? It has dropped below freezing here in Portland, Oregon a few times over the last couple weeks. The lemon grass is discolored (purple), the upright thyme is beginning to show some discoloration as well (also purple) and the rosemary looks healthy and green. What are the preferred methods of drying in this instance?. Would you harvest them at all?
How do freezing temperatures effect herbs?
You can very probably eat the rosemary all winter. Even if it goes dormant, the succulent leaves kind of get "freeze dried" %26amp; are still edible.



I live in zone 5, where it gets down to 20 below 0 in the winter, and I eat thyme all winter long. The purplish color doesn't seem to change the flavor. Like the rosemary, even if it's frozen solid it's still tasty.



Lemon grass is fairly tropical. I would harvest it and dry it. My favorite way to dry herbs is to set them on a wire rack or screen. Indoors, in a heated house, they should dry out within a week.



If you want to dry the thyme and rosemary, you can tie them in bunches %26amp; hang them upside down in your house. But I don't see any reason to do that with the rosemary %26amp; thyme, unless you just don't like going out into the cold to cut it.
Reply:Rosemerry and chives will handle the cold...thyme will not as well as basil and oregeno and most others..I grow mine from my deck railing that I made planters for, then about two weeks ago i transplanted cuttings from the ones not "cold hearty" and bought a flourescent grow light to keep them going inside all winter...This light, fixture and all is only 9.95 at wal mart..below are a few pictures of them outside..then My recent transplant of some to the inside...The light looks purple but it is white..just the lavender walls give it that effect..As long as you keep the room you have the light in ariound 60 to 65 degrees ..they will grow..Do not overwater inside herbs, for this is what kills most of them grown indoors.. water only when you can stick your finger in the soil and it is dry about 1/2 inch down..root rot is the major concern..No direct sun so the water does not eveaporate, thus needing water very seldom...heres a few pictures..Here is the herb cuttings recently transplanted..I found A metal rack thrown away behind a store for this..then stapled plastic underneath for any dripping water..



http://www.flickr.com/photos/pcbeachrat/...
Reply:Most herbs are at their maximum potency just prior to flowering. Herbs should be cut between 10 am and 2 in the afternoon, at the latest. Herbs are at their peak when the dew has begun to dry. The essential oils are at their peak as they acclimate to the sun. The oils begin to decline in the afternoon. I think your lemon grass is past its prime. I live In Northern MI and I can harvest sage all winter although it does not have the flavor of summer picking. Rosemary should be fine but again, if it has flowered you will not get the maximum flavor. Once the plant flowers, its energy is going into seed output and winter dormancy. I think if your plants still look viable they can be used but you will not get the maximum flavor you can expect in summer prior to flowering.