Many people ask, “What is the difference between an herbal tea and an infusion?

An infusion of herbs is much stronger and has a more medicinal quality than just a tea.  Simply, an infusion is steeped much longer, many times overnight.

Making Herbal Infusions

Roots: Use one ounce (a big handful of cut-up root, or half a dozen six inch pieces of whole root) of dried root in a pint jar. Fill the jar to the top with boiling water. Put the lid on the jar and let it sit at room temperature for eight hours.

Roots are the most dense and usually most potent part of perennial and biennial plants. The medicinal virtues of roots are often found in their alkaloid content, which dissolves quite slowly into water. This is why many herbals suggest boiling roots; the rapid movement of the water molecules bouncing against the alkaloids frees them from the cells and extracts them into the water. I have found, however, that a very long period of infusion extracts all the useful alkaloids and medicinal substances from the roots, without the careful watching necessary when they are boiled.

Some roots and barks do not contain medicinal alkaloids (or have alkaloids that we wish to avoid) and these should be infused for only an hour or two. Slippery Elm bark, and Ginger, Valerian, and Licorice root are herbs used in this book which should be steeped for this shorter time.

Barks: Prepare the same as roots.

“Bark” is a misleading word, as the usual part of the tree or shrub actually used for herbal medicines is the inner bark, or cambium layer, which lies between the true bark and the wood. All the nourishment and life force of the tree, passing between roots and leaves, moves through this layer, making it a rich source of valuable resins, sugars, and astringents. The wood and the bark are dead cells and thus contain little that is medicinally useful. Cambium cell walls are tough, requiring long brewing for full extraction of medicinal virtues.

Leaves: Use one ounce of dried leaves (two handfuls of cut-up leaves or three handfuls of whole leaves) in a quart jar. Fill the jar up to the top with boiling water, put the lid on and let it steep four hours at room temperature.
Leaves contain the potent healer chlorophyll.

Long steeping extracts all the chlorophyll, as well as the vitamins, minerals and other medicinal components of the leaves. Steeping in a closed jar keeps the water-soluble vitamins from escaping in the steam. Some leaves are tough and leathery and need to be steeped for more than four hours; Rosemary and Uva Ursi are leaves used in this book which require longer infusing, up to eight hours.

Some leaves release their medicinal factors very easily in water. Catnip, Shepherd’s Purse, Lobelia, and Pennyroyal are leaves that require steeping for an hour or less.

Flowers: Place one ounce of dried flowers (two big handfuls of crumbled-up flowers) in a quart jar. Fill the jar up to the top with boiling water, put on the lid and infuse for two hours.

Flowers are the sexual expression of the plant. They are generally delicate and volatile. Chamomile is exceptionally volatile and should be infused for no more than thirty minutes. When the stalk and leaves of the plant are used along with the flowers, as with Yarrow, Red Clover, and Skullcap, infuse for four hours, as though it were the leaves alone.

Seeds: Use one ounce of dried seeds, berries, hips, or haws (one to three tablespoons) in a pint jar and fill it to the top with boiling water. Screw on a lid and infuse no more than thirty minutes.

Seeds are the embryo of the plant. Though they are hard and dense, like roots, they are engineered to open and release their properties immediately upon contact with water, so they do not need to be infused for a long time. In fact, if seeds are brewed for too long, bitter oils and esters are leeched out into the water and a nasty-tasting brew results. Rosehips and Hawthorn berries are exceptions; they may be steeped up to four hours.

Combination Infusions: When preparing infusions containing several herbs, it is generally best to brew the components separately so that each herb infuses for the proper length of time. This is unnecessary if the combination is all roots, or all leaves, or leaves and flowers treated like leaves, etc.

If you buy herbs which are already mixed and wish to infuse them, brew for the shortest time needed by any ingredient; for instance, a mix containing Chamomile should be steeped for no more than thirty minutes. Some medicinal potency will be lost this way, but you will avoid extracting bitter esters, oils, and resins which may cause unwanted side effects.

The Wise Woman tradition focuses on the use of simples. A simple is a medicine made from a single herb. When combinations are used, the formula rarely exceeds three herbs. This tradition allows for maximum feedback on the effect of each herb and rapid understanding of medicinal herbs.

Dosage: Two cups, sixteen fluid ounces, of an infusion per day is the standard dose for a person weighing 125-150 pounds.

Use one cup if you weigh 65-75 pounds. Half a cup for 30-40 pounds. A quarter cup (4 tablespoons) for 15-20 pounds.

General Times for Infusions:

Barks & Roots-Infuse one ounce in 1 pint of boiling water for 8 hours or overnight

Leaves-Infuse one ounce in one quart of boiling water 4-8 hours

Flowers-Infuse one ounce in one quart of boiling water no longer than 2 hours.

Seeds/berries -one ounce in one pint of boiling water up to  30 minutes maximum

Sources:

http://www.susunweed.com/How_to_make_Infusions.htm