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.

Soil

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.

Trimming

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.

Propagation

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.