Preparing and preserving medicinal herbs is easy once you know how. It depends on the herb and what you are going to be using it for. Some herbal medicines come from flowers, others from roots, stems, leaves, and so on.
Collecting Medicinal Plants
The first step is in knowing what you want and whether it grows in your area. This map can help if you are in the United States. http://www.slate.com/content/dam/slate/blogs/the_vault/2015/05/13/LgMedicinalPlants.jpg
Know what the plant look like so you can harvest it. Some photos from Google Images can help. Some can look very similar without a good picture to match it. Don’t pick within at least 1 mile of a highway, due to lead contamination from car exhaust fumes. Look for areas where the herb grows abundantly, which will suggest good soil. Pick around mid-morning, so the herbs are not soaked with dew, which can make them go moldy.
Take only the parts you need. If you need leaves, choose tender, unwilted ones. Avoid flowers that are losing their petals, because they will already be past their prime. If you need bark, cut small branches from the tree and then strip them. You don’t want to run the risk of ruining the whole tree with poor de-barking.
Put your herbs in small cotton or muslin bags. Keep separate to avoid confusion. Try not to crush your herbs on the way home.
As soon as you get home, dry your herbs to store them. The fast method is indoor oven drying. The slower method is outdoor frame drying.
In the oven, you can dry herbs in a matter of 1 hour that would take up to 6 weeks to dry on a frame. Spread out the herbs one baking trays so they do not overlap. Cover the trays with aluminum foil, reflective side down. Pinch the foil around the edges of the tray, leaving a small vent in one corner to let moisture escape.
Place the tray into the oven and set the temperature to 150°F. Bae 15 minutes. Remove the tray from the oven and turn the herbs over to ensure that the moisture is drawn out evenly from all sides of the plant. Re-cover and bake another 15 minutes. Do not allow plants to burn to a dark brown or black color or all potency will be lost. Test the herbs after 30 minutes and 45 minutes. If the leaves or other botanicals crumble in your hand without powdering, and it is a similar color to the original, it is fully dried.
The disadvantages of this method are that many people cook the herbs, not dry them, and they lose about 1/3 to 1/2 of their potency.
With frame drying, the herbs lose about 1/4 of their potency, but it takes weeks and you need the space. You need a wooden frame and will have to turn the herbs over every day. If any of the herbs are really damp, they can make a whole batch go moldy.
Once they are dried, they should be stored in a dry container in a cool, dry place for use in various forms of remedies.