Dog (Canis familiaris) hair is cheap, abundant, renewable, and produced in such vast quantities that one feels mortally certain that it must be good for something besides canine thermoregulation. Furthermore, most existing rooting media are dependent on the destruction of natural ecosystems (peat moss), require a large amount of energy for production (perlite), or pose a health hazard to the producers and users (vermiculite),1 so finding a more renewable medium would be a boon to both plant-loving dog owners and the environment.
As canine hair has some qualities in common (holds water, fibrous texture) with other substances used in rooting media and soilless potting mixes, it was evaluated for its potential as a rooting medium.
The floor of a home containing a dog ("Sheba," Fig. 1) was swept, and the sweepings collected into a pile. (Fig. 2) The sweepings were then separated into hair and non-hair, with the latter discarded. (Fig. 3) The material which resulted was fibrous and mostly dark gray in color, with inclusions of lighter matter.2
The hair was then added to a plastic pot, 7 cm in diameter. Non-hair material was left out of the pot when it was feasible to separate it. Once the hair had been placed in the pot, it was rinsed with water several times to remove water-soluble contaminants. (Fig. 4)
Next, the cutting to be rooted was prepared. We selected Plectranthus verticillatus (Fig. 5) as a test subject, because P. verticillatus is known to root readily under a large range of conditions. A cutting approximately 7 cm in length was taken from a plant (Fig. 6), and the lowest pair of leaves was removed.
After making a hole in the dog hair at the center of the pot, the end of the cutting was placed into the hole, and the hair packed around the stem to ensure contact between the rooting medium and the cutting. The pot was then placed in a brightly-lit but sunless location. Moisture level was monitored, and water added when it would have been added for a cutting rooted in soil.
During the first full watering, a considerable amount of dark brown material washed out of the rooting medium. Chemical characterization was not performed, and the identity of the substance is unknown. Similar but lighter yellow material was washed out of the medium following some but not all subsequent waterings.(Fig. 7) Rooting medium had no discernible odor.
The experimental pot retained water much longer than a comparably-sized pot of standard potting mix. However, the distribution of the water was quite different. The upper half remained relatively dry, even immediately following the addition of water, while the lower half stayed very wet. This made it difficult to determine when to water the cutting.
The oldest pair of leaves wilted significantly after three or four days. No new leaf growth was observed; a few small (< 2 mm) roots had formed by four weeks (Fig. 8). This is significantly less root growth than would have been expected from potting soil or water after an equivalent length of time.
After five weeks, the cutting remained alive but wilted, and had produced no new growth. (Fig. 9)
Though root development suggests that canine hair may be capable of rooting plant cuttings under some circumstances, development was slow compared to standard media, probably due to the different water-absorbing abilities of canine hair, and it is likely not an acceptable substitute for potting soil.
This experiment also demonstrates that Plectranthus verticillatus, contrary to popular perception, is not in fact capable of rooting in any material, merely in most of them.
2 The inclusions were primarily composed of household dust, lint, fragments of potting medium from indoor plants, and the fallen leaves of said plants.