Tuesday, March 31, 2009

Notes and Thoughts on Raising Dawn Redwoods (Metasequoia glyptostroboides) as Bonsai

The Dawn Redwood (Metasequoia glyptostroboides, hereafter referred to as “metasequoia”) is a surviving relict of a family of trees that goes back in the fossil record almost to the beginning of the Age of Dinosaurs – well over 200 million years. By about 40 million years ago, this group of trees was so successful that they enjoyed a world-wide, circumpolar distribution from the arctic to the lower mid-latitudes. But for reasons not completely understood, but most likely related to changes in world-wide climate, their distribution began to shrink and they were eventually pushed into isolated canyons where they survived in small groups. By 6 million years ago they had receded from North America and by 2.5 million years ago they appeared to have vanished from the Earth completely.

Metasequoias were thought to be extinct until the 1940’s when vague rumors of a mystery ghost tree caused teams of scientists from China and the United States to further investigate a small upland valley in the Szechwan province of China where a single isolated population of Dawn Redwoods was found to exist. Seeds brought back from that expedition were distributed world-wide to universities, herbaria and research facilities around the world and from those seeds a new world-wide population of metasequoia trees has emerged.

I first became intrigued in 1973 when, as an undergraduate at Michigan State University, I listened to a professor in an elective plant pathology course tell the story. He told us that one of those original 1940-era trees was growing on campus, and after class I sought out the tree and sat beneath it for hours, pondering its long journey. I am still fascinated and have well over 12 dozen of them growing at the Little Big Trees Bonsai Plantation in my yard. They range in size from tiny cuttings and seedlings that just began sprouting in late March, to one that I planted next to my driveway about 6 years ago and which has rocketed to over two stories tall!

Rather than going into an extended history of the tree (which I may do at a later date), I thought I’d relate a few of the things that I’ve learned over the years about growing and styling these marvelous trees as bonsai.


The biggest problem with metasequoias is that the leaf fronds are so thin and delicate that, if they dry out even once, it will likely kill the tree. They are very hardy trees but also very unforgiving to desiccation. Therefore, I have found that I have the best luck growing them in a soil that has been amended with a generous fraction of organic material to hold water. Bear in mind however, that the opposite is equally as true. Metasequoias are native to relatively well-drained, upland soils. A rich, soupy, organic mix will only promote root-rot. The key is not letting them dry out.

Plant Placement

Metasequoias grown in the ground can tolerate full sun (again, because they don’t dry out). Pot-grown trees should be placed beneath a screen, trellis or other diffusing agent to provide a “dappled sun” environment, especially from mid-June to late summer.

Watering and Feeding

These trees prefer a constant, moderate level of soil moisture. Too much water causes their bases to become rotted, mossy and/or salt stained. Too little water, again, causes them to dry out from the tips in. I feed them once a week, one-half strength, rotating a variety of feeds, but always including fish emulsion. Why? No particular reason, I just get the feeling that my trees react favorably to it.

You need to monitor them daily in the heat of the summer.


I remove each of my trees from the ground or pot each spring a trim the roots back to a fist-sized ball or smaller (depending of course on tree size). The roots grow back quickly and aggressively. I also trim the tops aggressively, trying to keep the trees in a compact triangular shape. This also promotes much denser branching. Metasequoias naturally assume something of an inverted teardrop or flame shape in nature. This doesn’t work well with bonsai because the branch lengths become too long and out of proportion. My trees all have more of a coastal redwood look. This is, of course, a matter of taste and practicality.

A neat trick that I’ve learned is too take a two or three inch piece of slate and wire it UNDER the roots, spreading the roots out laterally before repotting each spring. This splays the roots and forces them outward. (One of the world’s great abandoned slate deposits lies just across the Susquehanna River from Lancaster in York County, PA.)

The biggest thing with trimming metasequoias is that the branches grow VERY fast and bud-back is constant along the trunk. Therefore, whether you like it or not, you have to constantly and aggressively cut off your largest branches lest they quickly become out of proportion with the tree. Don’t worry they’ll bud back in profusion.

Another thing to consider: when topping your trees… and you must top your trees each year… rather than taking a vertical slice and wiring up a lower branch, try taking a cut above to opposite buds (they bud opposite) and the cutting off the “back” bud, leaving the front one to grow on. This often leaves less scaring and “herky-jerky” taper.


Two choices: seeds or cuttings. Cones should be collected when they fall and can be stored in the refrigerator. When they begin to open, put them all in a big coffee can with a lid and shake the heck out of them, liberating the seeds. Then mix the seeds with a rich organic soil like you were baking a cake, spread it out in a shallow bonsai pan and cover with 1/8” to ¼” of very fine gravel. (The gravel helps keep the surface drier and inhibits fungal growth in the early stages of the new plant.) I put mine out in the sun about two weeks ago and they’re already sprouting. Be sure to protect them from freezing weather in the early spring!

I’ve done a lot of experimentation with taking cuttings and am beginning to settle on the following: I leave my trees with their previous year’s growth over the winter and then around early March, I trim them to taste. I put all of the cuttings into water and let them soak a day or two. I select the best (and of course, “best” is highly subjective… ask me and I’m give you my two cents..) terminal cuttings, dip them in liquid rooting hormone (IBA) if I have it or powdered Root Tone if I don’t, and plant them in mass in a large wooden box in a moist, organic soil. The box is nice because I can move it from sun to shade and out of the cold. I just let them go. You rogue out the ones that are obviously dead and about mid-June plant the survivors in small rooting containers. I grow them on for one season and then pot them up to a small growth pot the next spring.

Sunday, January 4, 2009

A Dormant Cutting Looks Down Upon Its Severed Limbs

Bright and early on the morning of January 1st, 2009, as has become my custom for the past handful of years, I went into the Little Big Trees bonsai plantation and took dormant hardwood cuttings from my dawn redwoods, Chinese elms, gingkoes and hornbeams. I trimmed the best of the terminal and secondary cuttings into 4” – 6” lengths, labeled them, placed them in zip-lock bags, and set them in the refrigerator for the remainder of the winter. In late March, I will soak them in IBA rooting hormone, plant them enmasse in wooden planter boxes and let nature take its course. If past years are any indication, I will end the summer with at least another 10-12 dozen trees.

Even though I was told years ago that working with cuttings rather than seeds is a waste of time, there is just something magically satisfying about a disarticulated cutting. This plant-fragment awakens with an immediate disadvantage: it has been sliced open and exposed to invading disease, it has no easy source of rising sap, no roots in place to sample the sweet snow-melt waters of early spring. There is a moment when the cutting realizes this and freezes in horror like a soldier returned from war who awakens to discover that a limb has been amputated.

The cutting has no time for self-pity. It has a decision to make. It is root or rot. The cutting must move quickly to seal off the injured tissue and throw out new roots. To do anything less is to allow the integrity of the exposed tissue to be compromised and to succumb to rot and desiccation. It was described to me once in vivid terms: There is a moment when the cutting screams out “I live!”

All of the trees that I raise from cuttings have survived that moment and have made that decision. They don’t live through some miracle of genetics or accident of biology. They have each made the decision to live. They WANT to live. They live.

I believe that this imbues them with a special character that seeded plants may lack.

Tuesday, December 23, 2008

The Bonsai Paradox: How Do We Keep Trees Small?

One of the most frequent questions that we receive from people unfamiliar with bonsai (after the question: “how do you keep them alive?”) is “how do you keep them so small?” The general public seems convinced that our wee trees are Lilliputian freaks that have been coerced through starvation and bondage. Maybe yes, maybe no, but before we address the question of how to keep a bonsai small, it is helpful to first ponder the question of what bonsai is.

Bonsai is the artistic cultivation of miniature trees in containers - grown and styled to defy time, gravity and perspective. Bonsai is really just an illusion that inhabits the intersection of science, art and horticulture. It is an illusion in the sense that the bonsai artist attempts to convince the viewer that the tree is something that it is not. It has been said that bonsai is a paradox: trees are manipulated to make young look old, to make tall look short, to make large look small, to make healthy look tortured and to make otherwise sensible trees appear to defy gravity.

You have seen proportion diagrams of the human body. If pictures of a new baby, a growing child and an adult are all proportioned so that they are the same height, and set next to one another, the head of the baby is much larger in comparison with that of the child or adult. The head of a baby may constitute up to 1/3 to 1/4 of the total length. In an adult, this fraction falls to 1/5 to 1/6. It is this relationship that makes each stage in development so immediately recognizable.

The same is true with trees. Young trees grow long and thin as they stretch to reach above the canopy to the sun. There are fewer branches, and the distance between branches is greater (relatively of course). The ratio between the width of trunk and width of branch is small. Old trees, on the other hand, have remarkable taper. They have thick, expressive trunks that progressively thin through smaller and smaller branches until they explode outwards in a spray of fine branchlets with leaves. Old trees have thick, well-developed roots that often protrude above the ground, and the trees themselves are often gnarled and seemingly tortured by exposure to the elements. If you take a picture of a young tree and a very old tree and scale them to the same size, they look very different, with recognizable differences in trunk girth, shape of the crown, and density of fine branching.

So, back to the original question: “How do you keep bonsai small?” The simple and obvious answer is that you trim them aggressively. You cut the branches back to reduce the distance between branches and to encourage taper and fine growth, and to CREATE THE ILLUSION OF A LARGE, OLD TREE. You trim the roots to encourage a fine, dense, healthy root mass with a higher proportion of root hairs to woody roots. By cutting back the top and the bottom, you allow the trunk in the middle to continue to grow and develop, enhancing taper in both directions. By reducing the root mass, you are able to place the trees in ridiculously small pots, further creating the illusion of size and age, and causing the tree to appear to defy gravity. (Although as we know, it is actually wired into the pot to keep it from falling over.)

However, the other, more complicated part of the answer involves nature vs. nurture. By forcing the tree to deal with limiting conditions, the tree learns to develop new ways of coping: growing smaller leaves, reconstituting its root mass, throwing out new branches where none existed before, adapting to new nutrient supplies. In essence, we convince the tree that it can make a better living as a small tree rather than a large one. In so doing, we create large, old trees out of little, much younger ones, and we keep our old trees small.

So next time someone asks you how you keep your bonsais so small, look thoughtful and reply: “I don’t keep my bonsais small. They do it themselves.” Then smile and change the subject.

Let’s keep the illusion and the paradox intact.

A Green (And Red) Thumb For Christmas

What then, exactly, is a green thumb?

Why is it that some people on this planet are able to endlessly surround themselves with lush, thriving plants that seem to grow themselves, while others couldn’t keep a cactus alive if their own life depended on it?

Those who can’t, attribute this strange power to something mysteriously referred to as a “green thumb”. But those who can, know better.

There is nothing mysterious about a green thumb. It’s not like trying to hit a round baseball with a round bat, interpretting tax law, or solving quadratic equations. It’s not a secret skill passed down from teacher to student since antiquity by covert growing societies, and it’s not a special “gift” bestowed by Mother Nature.

A green thumb is really just simple empathy. It is the ability to sense what a plant needs and to provide it - when the plant needs it. More importantly however, it’s the ability to just stand back and stay out of the plant’s way. In the end, it may be that last part that is the most important.

Plants are marvelous evolutionary inventions. They, and they alone, have discovered a way to harness the naked energy of the sun and to package that energy into little parcels that can be used in a myriad of ways. Plants are able to take the most basic of substances – water, carbon dioxide and what nutrients they can scrape from the soil – and produce structures and substances of the most amazing complexity.

Back before we began to put plants in containers, they grew in the ground. They tied their tap roots into the soil and then sent the other roots off in search of food and water. They raised their tops towards the sun, the source of it all, in spirited competition with other plants for the best position. They discovered, through trial and error, what to avoid and what to seek out. They learned to move away from gravity and towards the light. They learned to trust the climate and to avoid the weather. They learned how to continue to grow, regardless of the damage, change or misfortune that was passed their way.

As some wise old fart once said: “If you take a tree from the environment and put it in a pot – you owe that tree!” Here’s hoping that your happy plants are giving you a green and red “thumbs up” this Holiday season.

Chlorophyll's Retreat

Autumn. The weather may not know what time of year it is, but the trees surely do. Even a huge sugar maple, lounging quietly at the edge of the woods overlooking dry, beaten-down fields, is exhausted. Its leaves are dull and worn, riddled with the wounds of insect wars, mottled with faded yellows and edged with the brown of rot and desiccation. For this old maple there is no more growing to be done this year, not above ground at least.

The trees, the deciduous ones at least, know that it is time to begin to invest their gains, cut their losses and close up shop for the winter. Deciduous trees are like Europeans. Each year, they take an extended vacation at the most advantageous time of the year. It’s part of their nature, their heritage. They use the time to assess, regroup and renew themselves. Evergreens on the other hand, are more like Americans. Evergreens seek to eke out a living continuously, regardless of conditions, with less concern for such frivolities as taking time off. Figuratively, you would never see an evergreen wearing a tiny Speedo at the beach.

Spring seems such a long time ago. But one perfect night last spring, in response to some mysterious combination of increasing day length, the warming of the soil, and the jump-start of the hormone factory, the trees threw open their buds, and unfolded delicate leaves like the damp new wings of a butterfly. These wafer-thin leaves stretched between strong veins exposing thousands of square feet of tiny chloroplasts jammed with chlorophyll to the sun.

Chlorophyll is a complex and relatively unstable compound that is able to perform miracles with sunlight. But for all of chlorophyll’s complexity, its primary function is simply to use the sun’s energy to split open water molecules. In doing so, a cascading stream of hydrogen ions are liberated that rocket around like bowling balls setting a whole new series of sun-capturing reactions into motion. During the summer, chlorophyll is continuously used and must continuously be replaced. It’s rich green color dominates the lesser yellows, oranges and purples of other pigments. But in the fall, when the tree no longer needs to produce energy, the production of chlorophyll ceases, allowing the leaves to finally sport the dramatic fall colors of carotenes, xanthrophylls and other pigments laid bare by chlorophyll’s retreat.

In the fall, those tender young leaves that once provided precious surface area to capture the sun, now pose a liability, and expose thousands of square feet of surface area to the killing winds of winter. The deciduous tree makes the decision. It will rid itself of the leaves, but only after it withdraws all available energy sources back into its interior, deep into the tissues and roots, where it can be stored until it is needed next spring. To be ready for spring, the tree produces tiny buds that spend the winter exposed, like paupers with blankets pulled tightly around their shoulders. They turn their backs to the wind and the cold and hunker down like a small pack of hobos, huddled around a garbage can fire. They reduce their needs and try to outlast winter – the long, long winter - waiting for the day to again lengthen, the soil to warm, and the hormones to again flow.

And then on a perfect night in the spring, when it can wait no more, the tree relaxes. Stripping the blankets off the shoulders of its buds, it unfurls leaves like tiny flags and makes its charge – running screaming to the sun as naked as the day it was born.

A Dormant Tree Wakes In The Middle Of The Winter

It’s the middle of the night. You awaken with a start to pitch darkness, a little lost and surprised, more than a bit disoriented. You could be anywhere and it could be anytime. You glance at the small clock at your bedside and realize that its only 4:30 a.m. It’s early. You still have a couple of hours until you HAVE to get up. Reoriented and reassured, you pull the covers up to your chin, snuggle deeply back into your spot and resume the refreshing sleep of the recently-back-to-bed.

Dormant plants in the winter can’t be much different. They too are occasionally awakened from deep slumber by a January thaw, or a string of sun-on-your-face warm days that remind all living things that Spring is just around the corner, somewhere. The plant too is disoriented and surprised. Is it time to get up? Is it time to wake up the buds and start pumping sap up from the roots? The plant glances at its bedside clock – the sun – and gages the time until it must arise from dormancy. It’s hardly mid-January. The plant doesn’t have to rise and shine until at least the 2nd week of April. Reoriented and reassured, it hits the snooze alarm and goes back for more rest.

By comparison, a dormant tree stored in a darkened basement or windowless garage as no sense of the time of year other than its own marvelous internal clock. It knows that it certainly must be mid-February but it has no way to verify it. So it lays half-awake, half-asleep, afraid that it will oversleep. The rest it gets is fitful, the final awakening abrupt.

I have no scientific evidence to back this up. It’s just a hunch.