This is the second in a series of articles on using Dawn Redwoods (Metasequoia glyptostroboides) as bonsai*.  The first article was posted on Open.Salon.com, littlebigtrees.blogspot.com, and lancasterbonsai.com in the early spring of 2009.   Although it passed with very little notice on OS, it enjoyed a strong readership on the Internet. For a brief bio/geologic history of the metasequoia and general hints on care, the interested reader is referred to the original article: “On Raising Dawn Redwoods as Bonsai”. 

* Bonsai – the art and science of growing miniature trees in tiny pots

Part II - PROPAGATION – an update

When I left you in early spring, I had planted out cuttings in wooden planter boxes and the buds were just starting to open.  The question was: how many would survive rot and desiccation and live to throw out roots?  The answer lies below… but first a little background on methods of propagation.

There are three methods of propagating Dawn Redwoods: seeds, hardwood/ greenwood cuttings, and air layering.  Each method has its pros and cons (although personally I have settled on cuttings as, by far, the preferable method.)  A brief review of the three methods:

1. Seeds

Cones are collected when they fall from the tree and are stored in cool, uniform conditions (refrigerator)until they begin to open naturally. At this time they are placed in a container and shaken vigorously – liberating the tiny seeds.  In the spring the seeds are mixed with a slurry of soil and planted in seed trays.  Pros: easy to do, easy to judge the results.  Cons: low yield, seedlings highly susceptible to disease, very tiny plants at end of first year.  NOTE: Care must be taken to collect cones from mature trees, those that are at least 20-30 years of age.  Younger trees produce cones but not all are viable.

 (Seedlings, June 2009)

2. Cuttings

Branch tips are removed in mid-winter to mid-spring, treated with rooting hormone and planted and maintained under consistently moist conditions.  Buds open in the spring and leaves emerge.  If roots sprout sufficiently to maintain the cutting, a new tree is the result.  Pros: simple process, resulting trees already with hardwood trunk, resulting trees very healthy. Cons: variable yield. 

NOTE: Until this year I have used professional IBA rooting hormone. Unfortunately it is expensive and difficult to obtain.  I avoided Rootone powders because I felt that the powders induced rot. This year I switched to Rootone F because I ran out of IBA.  I have to suspect that the switch is at least a factor in the radically increased yield reported below.)

 (Cuttings with roots, approx. 3 months after planting) 

3. Air Layering

This method is by far the most difficult.  It is an advanced technique and readers should do their homework before attempting.  Basically it is a method for transforming the top of an existing tree into a completely new tree by girdling the trunk, removing an entire band of cambium, encasing the cut in soil and inducing the tree to throw out roots midway along the trunk.  When this happens the new tree is severed from the old beneath the girdle and planted out on its own.  Pros: two trees of considerable maturity can be produced in a short period of time.  Cons: subject to any variety of disasters, unreliable, low yield.  (Interestingly, although I only have two air layers going on this spring, both appear to be "taking" and throwing out roots.) 

RESULTS

In Pennsylvania so far this year we’ve had a consistently wet and mild spring and early summer.  This has resulted in optimal growing conditions.  In past years, my expected yield from cuttings was low – in the neighborhood of 15% - although this was still adequate to provide me with three or four dozen new trees heading into the winter.  This year, due to the wonderful weather and improved growing technique, my yield is so far in excess of 80%!  Frankly, this is more trees than I can deal with.  (Wanna buy some trees?) 

The first article detailed the cuttings procedure up through planting in the spring.  Let’s zoom ahead.  As of early June, I have planter boxes with hundreds of cuttings that have thrown out strong, healthy (and frankly,beautiful) roots.  I will let them grow as is through the end of June, and when Wimbledon starts it will be time to carefully remove the well-rooted cuttings from the soil and plant them individually in rooting flats.  The goal is to separate them and allow them to extend their roots without competition for the remainder of the growing season so that they enter the first winter with a well-developed and well-insulated root mass. 

In mid-summer of next year I will pot them up to 4” pots where they will live for another couple of years.  The goal here is to let the tree form a thick and healthy root ball which can then be trimmed and flattened as necessary.  After three or four years, those trees with interesting and unique bonsai characteristics are repotted into rectangular bonsai training pots, those that need “fattening up”are planted in the ground, and the remaining trees are root pruned and top pruned aggressively to induce them to develop “little big tree”characteristics.

Throughout the entire process I trim the trees aggressively to maintain shape and to encourage “budding back”of growth within the tree.  This produces a tree that is denser and more compact, is less spindly and which retains the characteristics of a mature, full-size tree.  Assertive leaders are immediately removed. 

(4-5 year-old rooted cutting showing interesting branching characteristics)

GENERAL THOUGHTS

Obviously, I am intrigued by this species of tree.  I find it honorable, beautiful, historic and full of life.  It bridges the gap between art and science.  It bridges biology and geology.  It bridges hundreds of millions of years and links us directly with the dinosaurs. (Metasequoia cones and leaves are prominent in dinosaur-age strata and have been found in fossilized dino dung.) Despite the fragility of their nature, I have lost very few trees over the years.  Those that have passed have done so because it was in their nature – they were weak, or sick, or simply unsuited to go on.  In that way they are like humans.  But also like humans, metasequoias find a way, and those that are strong develop into a myriad of personalities, each of them unique. 

(Fossil metasequoia leaf in sandstone, modern leaf) 

(Coming next: Part III – Trimming and Styling Metasequoia)

NOTE:  Jeff Howe has been a bonsai enthusiast since 1998, is a past-president of the Lancaster Bonsai Society and is the proprietor of the Little Big Trees Bonsai Plantation.  He specializes in metasequoia, gingko, Japanese maple,Chinese elm and root-over rock.  He can be reached for comment at jeff.howe@verizon.net