I first saw bonsai soil covered with cottonseed hulls while observing a program by Mike Kling.
He was creating an extensive mini-landscape (including mountains, valleys, streams, rivers etc.) on a large restaurant carry tray. It was quite a unique undertaking.
Mike attributed much of his success to using these hulls instead of 'muck.' It kept the geographical formations in place, and added texture to the landscape.
Hulls are the covering of the actual cotton seed. When cotton is processed, this is what remains. It is then bagged and sold as roughage for animal feed (cows and pigs). Hulls are not to be confused with cottonseed meal, which is used as fertilizer.
Hulls have a very small amount of leftover cotton mixed in, giving them a “fluffy” look and feel (before they are soaked in water).
Once they are wet and in place they become darker and have a neutral ‘earthy’ appearance.
Moss and other ground covers should be
planted directly in the soil. In time, they will spread over the hulls.
In bonsai circles, these hulls prevent soil erosion in shallow saikei landscapes and root-over-rock plantings. They replace the muck mixture which is often so thick roots can barely penetrate it. These hulls are a great alternative to muck and in many cases a preference.
Another good purpose is a “natural” ground cover to deter weeds in a garden - instead of using chemicals. More good news: they are porous, the water drains right through. They are also very clean to work with.
Dr. Leon Snyder first discovered the value of cottonseed hulls in his work with micro-environments. He was a frequent guest at bonsai conventions in the 1970s, where he introduced them to the bonsai world.
Leon explained “the cotton fibers stick to the hulls much like Velcro.” They stick to themselves easily when patted together.
I inherited this imported Trident Maple root-over-rock bonsai, and wasn't sure how well it would do deep into Zone 10. It did just fine! It seemed to especially enjoy the occasional cold winters, and stayed dormant until early April. In this photo it is just budding out. The roots are prolific and need to be pruned annually.
I chose a very shallow Japanese container and used cottonseed hulls to keep the coarse soil from washing away, until the roots were established.
Start with a small amount of hulls. Allow for expansion, they almost double in volume when saturated.
SOAK amount to be used in a container of water for at least an hour, best overnight.
Take a handful of hulls lightly squeezing, but without removing all the excess water, and begin lightly placing a thin layer on top of the bonsai soil/rock or other area as needed and tap it in place.
Cover all the soil, tapping it as you go. Place it especially where you want to avoid erosion.
During the first couple of hours after placement, occasionally
mist or spray lightly with the hose to help the hulls set. Firmly tap
Wet? Absolutely NOT! There isn’t much that smells worse than “rotten cotton” and it can (and will) attract rodents.
When used as recommended it neither smells nor attracts rodents. Store dry leftovers in a closed, air tight container. If kept dry, they last a long time. I purchased a large amount for the nursery and some lasted for ten years.
After several months (possibly more depending upon your climate),
cottonseed hulls on soil begin to break down. If needed, they are easily
Try a local farm supply or feed store (not garden centers.) They are often used as filler in animal feed in many parts of the country. These hulls are used mostly in the southern area of the U.S. If your feed store doesn’t have them, ask them to place a special order for you.
They are inexpensive, however they are usually packaged in 50 lb. bales. You may want to find some bonsai friends who share you enthusiasm for experimenting!