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Making Bonsai Pop with the ‘Root over Rock’ Technique

Bonsai is an ancient art that strives to attempt the mimicry of sights and developments seen in nature. In this tradition, it is only natural that Bonsai artists would want to copy the breathtaking phenomenon that occurs in nature when a tenacious tree begins its life journey in the crevice of a rock and has to use its roots to find more nutrients when its original source has been depleted. As soon as the roots reach nearby soil, they harden up and begin to grow around the rock with the roots acting as the tree’s trunk. Another instance of this happening in nature is when a tree actually starts growing on another and eventually overpowers its host by 'strangling it' with its roots. Both situations embody the life force that is found within all living things, and in Bonsai, is a wonderful commentary on the balance needed to survive in adverse situations. There is beauty to be found in struggle, and Root over Rock is the magnification of this truth. 

In order to train a Bonsai in the Root over Rock style, you must first consider the natural tendency of the plant to develop long roots. You will need a plant that has long, tough roots that can be styled to drape over the rock that you choose to create the effect that the roots have grown over and down its rocky sides.  If the plant doesn’t have a naturally long root system, you can encourage roots to grow longer by planting the tree in a tall, thin pot for a year or so, until the roots are long enough; they will need to be at least one and a half times the height of the chosen rock. Developing root-over-rock bonsai is a simple but time consuming technique, so be patient with your creation, and you will be well rewarded.

You will need the following to begin:

  • A rock that appeals to you and that is a suitable size, it is important to note that the rock will become part of the bonsai, and should be chosen with the understanding that it is here to stay.
  • A Plant with roots suited to root over rock style; select a plant that has  roots that grow quickly and are quite thick and fleshy.
  • Plastic Grafting Tape
  • Raffia
  • Scissors
  • Concave Branch Cutters
  • Bonsai Secateurs
  • Chopsticks
  • Knife
  • Root Hook/Fork
  • Clean, Sharp Sand.
  • Bonsai Soil

It is important to remember that this style of Bonsai should not be attempted until spring when repotting and root work will be less stressful for the plant.   Once your chosen plant has roots that are long enough you will need to cut off all unsightly or unnecessary foliage and wash as much soil as possible away from the root ball of the plant while being sure to avoid any damage to the roots.  Try to remove as much soil possible by hand first, and then wash gently with a standard garden hose; remember, the closer to the rock they can be attached, the better!  After the soil has been removed, take your chosen rock and your plant and place the plant over the rock and take your time experimenting to see what arrangement looks best. Try to not place all of the roots to one side, as bonsai should be able to be viewed from all directions. Take note of the interesting crevices, nooks and crannies of your rock and implement the roots of the plant into these areas, you can even overlap thin, undeveloped roots, which, if left long enough, will merge together just as they would in nature; this attention to detail will make the finished bonsai look as natural as possible.

The roots of the bonsai must be grown in such a way that they grip the rock or stone securely for both the stability of the tree and the integrity of the piece. To ensure that the roots remain in the desired position, you will want to tie them into place with some strands of raffia; these will rot away with a few months and will not cut or mark the root surface, which is important ascetically.   Secure the roots well against the rock surface in this way, and then place some grafting tape to set the roots in place.  Wrap the grafting tape around the rock with reasonable firmness, making sure to cover it completely except for the bottom, were the roots will protrude into the soil. Also make sure that there are no areas where roots can escape from gaps in the grafting tape where they are not supposed to be.

After the roots have been set in place and you are sure that all of the roots protrude from the bottom of the rock you will then need to bury the entire rock with the plant in a mixture of clean, sharp sand and bonsai potting soil. It should be planted so that no part of the rock is visible and the bottom part of the trunk of the tree is visible. Thoroughly water the bonsai, and leave it in its training pot for one to two years.  If the plant is especially fast growing, one year of root growth may be enough time for adherence to the rock, but if you do attempt to transplant and discover that it’s not quite ready, you can always repot it and leave it for another year.  Remember… to develop root over rock bonsai is an art that demands patience.

Once the pot is taken away, the soil is removed by scraping gently with a chopstick or paintbrush and then washing, to expose the rock and root ball that has adhered to the rock. You will want to be gentle so that you don't damage any of the established or newly formed roots; to be careless will cause quite a lot of undue stress to the plant.  Now that your bonsai is ready, you will want to choose a suitable ceramic bonsai pot to display your creation.  Root over Rock styles look really lovely with shallow, oval pots…but be sure to let your own taste guide you!  Repot your plant in the chosen pot, and fill with potting soil suitable for the type of plant you have chosen; water till runoff at bottom of pot is seen, wait a few minutes and then water again to ensure adequate moisture.

At this stage, all plant growth should be allowed to remain for at least 6 months. Though new growth is allowed to stay for the time being, it can be wired to gently position “wild” branch growth. In this way all growth helps to bind the tree onto its new rock home.  In the next stage of training unneeded branches can be removed and more wiring will be done to reinforce the design.   Keep your bonsai in a warm environment with bright light or put outdoors for the summer.  When watering your bonsai, you will want to be sure to keep the rock and soil moist foregoing fertilizer regimes for at least 6 weeks. 

Overall, the dramatic 'root over rock' is a stunning and aesthetically appealing style. It is considered an advanced style, although is not too difficult to achieve with a bit of practice, patience, and the right materials. Be bold…you can do it, and results are well worth the effort! 

DISCLAIMER: The content provided in this article is not warranted or guaranteed by Bonsai Outlet. The content provided is intended for entertainment and/or educational purposes in order to introduce to the reader key ideas, concepts, and/or product reviews. We are not liable for any negative consequences that may result from implementing any information covered in our articles or tutorials. Happy bonsai gardening.