Herbs that are used medicinally should be restock indefinitely, the most being six months as the active ingredients in plants will escape with time. As we can't control time, it is better for us to change the herb (laugh). Anyway, I used to have a spell to stop time, if I could remember it...
Well, enough for the craps. If the herbs are intend to be used for cooking (or for mere flavouring), it is alright to keep them for up to a year. However, this herbalist wannabe disagrees completely as herbs used for cooking usually have their own benefits. For example, the addition of Oregano into soups and dishes will help to decrease microbes content, especially the deadly E.Coli. Also, is the antiseptic properties of Thyme, that will deteriorate with time (wow it rhymes).
Alright, after so much babbling, how are we going to effectively preserve herbs? There are numerous ways of storing herbs i.e salting, refrigerating, drying, and tincturing. I discovered that tincturing can be done using glycerin but it is out of scope of discussion in this blog as I only discuss about traditional methods of preparation.
Perhaps the not-so-common way of storing herbs but hey, you can flavour your salt as well. It works like this, the salt, osmotically lower in water potential, will draw out water from the hypotonic herbs. This will dry up the herbs indefinitely, and if done in a cool place, lessen the probability of chemically altering the herbs. However, this is possible as heavy introduction of sodium ions (Na+) will cause some of the active ingredients in the herbs to disintegrate. The common salt-preserved herb is Dill and I can give not much example for it. This method of preservation cater mostly for culinary purposes.
The all-so-common and express way of storing herbs. As I believe all of you know the difference between the crisper and the freezer, do store the herbs in the crisper together with the vegetables. Herbs stored in this way does not last long, so don't be greedy with the clippings in the garden. Use the herbs stored in this way within two days of purchase or clipping.
The commonest of all ways to effectively preserve herbs is to dry them. Drying cannot be done under the sun (however, this differs in view with the Chinese, who tend to dry their herbs under the sun) as this will alter the volatile oils, promoting their escape and disintegrating various active principles in the plant. Follow the steps below to dry herbs:
Tie the herbs in a bunch, if the part in question is of the root, make sure you cut them lengthwise before bundling. If you are using a wire-rack, arrange the individual sprigs on the rack.
Hang them upside down in a well ventilated room,if it is winter, try to either utilise the fire place for an hour or maybe the oven. Care must be taken however not to exceed 35°C as this will affect the volatile oils and the active ingredients. If you are using the rack, put the rack on a table, and leave it there, and as note above, you can place them near a fire place or a heater.
After drying, break the herbs into fragments and store them in darken jars, opaque paper bags or tins. They will keep for six months in a dark cool place (do replace them every six months).
Tincturing is the favourite method of preserving herbs among the Chinese. Not only herbs are preserved I am afraid animals such as little baby mouse and snakes are preserved this way. The reputed tincture is said to be infused with certain properties and drunk happily. Terrifying but I can't dismissed them completely as I have not done any research on it. O tincture herbs, do the following:
Place 115g dried herbs or 300g fresh herbs into a jar.
Add 250ml of vodka and 250ml cup of water.
Steep in a sunny place for two weeks. Strain. Store in a dark and cool place for up to 18 months.
This method can be used for all kind of herbs ad if you have a recipe for a blend, ration it accordingly and who knows, you might create an elixir of immortality.