The text comes from Susun Weed, a great herbalist whom I wholeheartly reccomend. It is easy to find her books, podcasts or videos, she is a great educator of herbal medicine.
An infusion is a large amount of herb brewed for a long time. Typically, one 25-30gr of dried herb is placed in a 900ml-1l jar, which is then filled to the top with boiling water, tightly lidded and allowed to steep for 4-10 hours. After straining, a cup or more is consumed, and the remainder chilled to slow spoilage. Drinking 2-4 cups a day is usual. Since the minerals and other phytochemicals in nourishing herbs are made more accessible by drying, dried herbs are considered best for infusions.
I make my infusions at night before I go to bed and they are ready in the morning. In the morning, I strain the plant material out, squeezing it well, and drink the liquid. I prefer it iced, unless the morning is frosty. I drink the quart of infusion within 36 hours or until it spoils. Then I use it to water my houseplants, or pour it over my hair after washing as a final rinse, which can be left on.
I use these five nourishing herbal infusions regularly, drinking at least a quart a week of each one:
nettle leaf (Urtica dioica): nourish and rebuild adrenals, kidneys, blood vessels, skin, hair
oatstraw (Avena sativa): longevity tonic, rebuilds nerves
red clover blossoms (Trifolium pratense): my anti-cancer ally,
linden flowers (Tillia americana): anti-flu, anti-cold, lovingly soothes lungs and guts
comfrey leaf (Symphytum officinale): heals, nourishes brain, bones, mucus surfaces, skin
I also use, for excitement or for specific reasons, these nourishing herbal infusions:
chickweed (Stellaria media)
mullein stalk and leaf (Verbascum thapsus)
raspberry leaf (Ideaus sp.)
hawthorn berries, leaves, and flowers (Crateagus sp.)
elder berries or flowers (Sambucus canadensis)
burdock root (Arctium lappa)
violet leaves (Viola sp.)
plantain leaves (Plantago sp.)
marshmallow root (Althea off.)
slippery elm bark (Ulmus fulva)
I only use one herb at a time in my infusion. I keep it simple, so I can really get to know the plants -- and my self.