I have used willow in the water for brugs... Couldn't really tell you if it made a difference.. I have several that are very sloooww to root and others that it only takes a few days...So long as they are still healthy keep that water clean and patience...
Aspirin...NO CLUE!!! But I would like to know!!!
Chena

I found this excerpt from a google.com search:

The Theory Behind Willow Water

Aspirin mixed with water has long been used by many to prolong the life of cut flowers and to increase the strike rate of cuttings. Aspirin is a natural anti-coagulant; meaning it stops/slows the processes by which fluids are converted to solid states/congeal. Some may also know Aspirin for it blood-thinning properties. Aspirin would seem to have a similar effect on plants, hindering the ability of the plant to clot up the damaged/cut end of a cutting or root and promoting the ability of water to enter the cutting and so sustain the plant itself whilst it self-heals.

Interestingly, Aspirin is derived from salicylic acid, a product naturally found in Willow bark! There may also be other chemicals/hormones involved that promote rooting but the salicylic acid seems to be the primary cause.

There is evidence to show that Salicylic Acid has an influence on blocking the wound response and effect of Abscisic Acid. Abscisic Acid is a stress hormone released by all plants in response to wounding or disease; it induces rapid closure of plant stomata and the 'shutting down' of injured areas of a plant.

So we come full-circle, the Willow cutting releases chemicals into the water, this promotes its ability to absorb water and to take root. This water is then free for us to use to promote rooting in other plants!

I started using willow water on some of my harder to root plants. I had better than normal results but I don't know if I can attribute my success to the willow water or some of the other things that I did differently. I have a feeling that the addition of bottom heat was the main factor for most of the cuttings rooting. I didn't use it for brugs because they root easily enough with just an air stone or nothing.
Karyn

Well, it couldn't hurt---but why not just use rooting hormone?

I used willow water for newly potted plants and I've also added it to the water that I rooted cuttings in. I've tried adding rooting hormone to water that I have cuttings in but I get a weird tan precipitate in the bottom of the container after a while.
Karyn

Karyn, that's why you don't add the rooting hormone to the water---you dip each cutting into the rooting hormoe. And with rooting hormone, less is better than more. Rooting hormone powder isn't water-soluble, so what sticks to the plant stays on the plant.

I use aerators when I root cuttings so it won't adhere to the plant for me.
Karyn

Thanks everyone. Interesting contributions. I went out and clipped some willow twigs and will likely just stickem in the bucket....can't hurt.

Hello forum. I'm a new visitor here, a search that I was doing on this very subject led me to this post. I thought I would share with you what I found on Ehow.com, maybe it will be useful to some of you. I think I am going to try this one.

A rooting hormone or tonic promotes root growth in plant cuttings. You can buy rooting hormone at nurseries but if you have willow trees nearby, you also can brew up your own.
Instructions
STEP 1: Gather a handful of chopstick-size willow twigs. Fresh branches work best; avoid deadfall. Any variety of willow (salix) will work since they all contain the natural chemical IBA (indolebutyric acid) - a natural plant growth regulator. STEP 2: Chop the willow stems into 3-4 inch pieces with clippers or a cleaver. You should have about 2 cups of clippings to make a one gallon batch of willow bark rooting hormone. STEP 3: Place the chopped willow pieces in a large container and cover with 1 gallon of boiling water. STEP 4: Allow the prepared willow bark tea to stand overnight. The longer it steeps, the more IBA will be released into the water. STEP 5: Store the willow bark rooting hormone in the refrigerator in a sealed container. Label the container. STEP 6: Soak tip cuttings into the willow bark rooting hormone overnight prior to planting in soil. The IBA will infuse into the bark and stems encouraging rooting and inhibiting fungus, bacteria and viral disease. Overall Tips & Warnings
Willow bark rooting hormone will stay fresh up to two months in the refrigerator.
Water young plants with willow bark rooting hormone. The salicylic acid from the willow will help defend plants against bacteria, fungus and viral diseases.
Evidence shows that salicylic acid works by aiding the wound healing process. Absicsic acid is a stress hormone that all plants release in response to injury. It stops the movement of fluids through the system and shuts down' the injured area. The salicylic acid found in willow bark tea works to inhibit the wound response, hence allowing growth.

Put Hydrogen Peroxide (H202) in your water with the rooting. I swear by using it!

Here is a link that might be useful: Hydrogen Peroxide Uses