If you've had the good fortune to see a full sized tree
with it's roots growing over a boulder, you understand why the "Root Over
Rock" or "Rock Clasping" style is so prized by bonsai people. As with
all good bonsai styles, it copies things that happen in nature. When a
seed sprouts from the ground, thick "anchoring roots" form, and grow down
and slightly outward from the trunk. If a root meets a rock, it grows
along the rock to the edge, then continues its downward journey. If there
is a boulder a few feet beneath the surface, all the "anchoring roots"
grow along the rock in an outward pattern away from the trunk. If the
weather conditions and/or terrain cause soil erosion, you have a candidate
for a natural "root over rock" tree. It can take decades, or even centuries
for the eroding soil to expose the boulder being grasped by the thick,
gnarled roots, but when it happens, it's a sight to behold.
To copy this
style, you'll need a tree that develops thick roots and can be bare-rooted,
a deep bonsai pot, some live moss, and some fast draining bonsai soil. Maples
are good temperate-climate candidates, and Serissas are good sub-tropical
candidates. You'll also need a good rock. Try to find one that's egg shaped,
and between 5 and 12 inches from top to bottom. If it has grooves
& crevices running from top to bottom, that's a plus, but a smooth one will
do just fine. If you need to "anchor" the roots to the rock,
but don't want to damage the rock, try this. Cut a 2 inch piece of wire
and place one end in the crevice where the root to be anchored will go.
Put a few drops of silicone or epoxy over the wire to secure it in place, and allow it to dry for 24 hours. Put the root in the crevice, bend
the wire over the root, and it will stay put. When that portion of the rock
is exposed, unbend the wire. If the root stays in place, remove the wire, chip or scrape away the silicone or epoxy,
and your rock is as good as new.
You'll also need some "peat muck". To make "peat muck", you put some
peat moss in a medium grade (larger than window screen) sieve and shake
it. Gather what comes through the sieve, and mix it with water to form
a thick paste. Place the rock in the middle of a bonsai pot that's two
inches or more deep. Put an inch or so of the fast draining bonsai soil
mix in the bonsai pot. Spread the paste in the grooves of the rock, or
if it's a smooth rock, cover it completely. Place your bare-rooted tree
so that the top of the rock is touching the underside of the trunk, and
drape the roots over the rock and down the sides. If the roots are long
enough, arrange then in the soil at the bottom, then add soil to fill
the pot. Next, cover the entire rock with moss that has been soaked and
flattened. (For information on working with live moss, see "Tip Of The
Week #12). To water, use a misting bottle. It is important that you soak
the moss covered rock. If the moss dries, the roots will die. Spray heavily
& often. Water the soil portion the way you water your other bonsai.
A few months after the bonsai begins to grow, peel
away an inch or two of moss from the top of the rock. Choose the 4 to
6 roots that will clasp the rock, Cut & remove one or two of the thinnest
remaining roots. Every few months remove another inch of moss and another
thin root. If in the process of doing this you reach the end of a root
that you want to grow into the pot, cover it immediately with moss, and
give it a few more months to grow before checking it again. Continue this
process until the rock is bare, and all the selected "clasping" roots
have grown into the soil at the bottom of the pot. You now have a Rock
Clasping bonsai. The roots will seem too thin at first, but with time
and good fertilization they'll steadily thicken. Adding a drop or two
of Super Thrive in all water will thicken them even faster.
To either change the pot or root prune this bonsai,
it is important to think of the rock as part of the tree. It will be decades
before the roots are thick enough to completely hold the rock in place.
When handling it, hold it by the rock, not by the trunk of the tree.
If there are any parts of this article that are
not clear, or if there is something you don't understand, E-mail me at
answer your inquiry, and if necessary, update this article.
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