Mid-America Bonsai Show 2014, Part 4. Kingsville boxwoods on "lace rock."

     I had never heard of "lace rock" until I watched Rodney Clemons create a group planting of Kingsville boxwood on an irregular slab of it, in his demonstration Saturday afternoon.

Rodney Clemons describing his plan for his demo. The rock is in front of him, the trees to his right,
and the ingredients for "muck" are on the floor to his left. August 16, 2014.

Lace rock, he said, is limestone that has developed pores and galleries as slightly acidic water has percolated thru it. (The same process on a different scale has carved out many of the famous caves in the world.) The resulting structure is a bit reminiscent of pumice, just not nearly as porous. It's still porous enough to hold some water, and natural hollows in the rock make great planting bays.

The best picture I managed to get of the rock itself.

(One member of the audience had heard something different: that lace rock is what is left behind after turquoise mining. I haven't been able to find definitive confirmation of either explanation.)

In the picture above Rodney is starting to mix his "muck" for planting. His recipe is simple:

• - 1 part chopped long-fiber sphagnum peat;
• - 1 part "Michigan" peat moss (the black, fine-textured product;)
• - 1 part powdered clay. (The idea of powdered anything in a planting medium surprised me, so I checked the bag afterward; the clay was almost as fine as talcum powder.)

Another perk of being a bonsai teacher: you can play in the mud and truly call it art!

An advantage of such a mix, of course, is that it keeps its shape well when applied to a sloped surface. But Rodney's muck recipe sounded to me like it would be very poorly aerated, except where air made its way in along the strands of sphagnum. So I asked. Rodney explained that in a case like this planting, the roots will grow thru the muck and into the pores in the rock, where there will be more oxygen.

A further advantage for the bonsaiist is that once the roots grow out - thru the rock - they will be naturally air-pruned; this will keep the whole tree compact. So a planting like this, he said, can go for decades without repotting and still stay perfectly healthy.

As mentioned, the trees for the demo were Kingsville boxwoods. Kingsville boxwood is Rodney's specialty, and he told us a bit about it as he worked. (I gleaned a bit more information afterward on-line.)

What we call Kingsville boxwood was discovered in 1912 as a sport of Korean boxwood, by a gentleman named William Appleby. When Appleby died, Henry Hohman bought his entire stock of the new boxwood, named it Buxus microphylla compacta, and released it to the nursery trade in 1937. Hohman's nursery in Kingsville, MD, was named "Kingsville Nursery," and the name stuck to the new variety. (So "Kingsville" is not part of the botanical name in any way; it's a common name, like "ponderosa pine.")

While above-ground a Kingsville boxwood is a genetic dwarf, below the soil it isn't: the root system is much larger than one would expect at first. This allows Kingsville to tolerate surprisingly heavy root-pruning, another advantage for the bonsaiist. An example in point: Rodney Clemons cut off at least 75% - I'm not kidding! - of the root system of each tree he used. (In August, too.) I thought at first that he had doomed them all, but he was obviously not concerned about that possibility!

(Rodney also mentioned that, because Kingsville boxwood is a sport, a grower has to be on the watch for two possibilities: reversion to the standard form on the one hand, and even further sporting on the other.)

Work in progress.

The slab of lace rock could have held at least half a dozen boxwoods of the size Rodney used, but he only had three (one of which he split to get a fourth.) He explained why. When a rock or a slab is used in place of a pot, it becomes a more important part of the composition. To use a theater analogy, it goes from being a supporting actor to being a co-star. So you want to show it off, too; and the best way to do that is to leave some interesting areas of it exposed. (He had made the same point the evening before in the Exhibit Critique; commenting on a forest planting on a slab, he told us that more of the slab should be shown off.)

The finished piece, from one angle. Darlene Kittle of the Fort Wayne Bonsai Club (green shirt)
looks it over from the far side.

From another angle. You can see here, and in the picture above, just how much of the rock was left visible.

Rodney's composition was the grand prize in the raffle at the Show banquet that evening. I understand that Mark Fields (see my previous post) was the lucky winner. Congratulations, Mark!

Next post (and last for this year's Mid-America): some other fine trees in the display.

:-)  :-)  :-)