There are two major advantages of growing this endangered tree from cuttings rather than from seed: (1) You can begin to harvest seeds in 4 to 5 years from specimens begun as rooted cuttings, rather than the usual 12 to 20 years for trees grown from seed. (In fact, if you choose a branchlet that has already begun to cone, you will need to remove the cones from the rooted cutting until it is big enough to support the energy demands of coning.) (2) It is a lot easier to obtain cuttings than it is to obtain seeds of this highly endangered species.
DISADVANTAGES OF BEGINNING FROM CUTTINGS: As with the ginkgo tree (which is usually rooted from branch cuttings of trees old enough to be sure they are male and will thus not produce smelly seeds), the growth form of a tree begun from a horizontal branch will be weird). See the photos below of the trees grown from 1991 rooted branchlets at Atlanta Botanical Garden: instead of a vertically trending main stem, the trees tend to lean and branch out more like a bushy yew. Also, while seed-grown trees will produce suckers at the base of the trunk, specimens grown from cuttings never will.
BEGINNING WITH VERTICAL STUMP SPROUTS (SUCKERS): If you begin with cuttings drawn from the vertically-trending stump sprouts found at the base of many specimens, then you will get a real tree-like form as a result. The disadvantage, of course, is that the onset of coning will be later.
HOW TO NURTURE A CUTTING: Atlanta Botanical Garden has great success in rooting many gymnosperms from branch cuttings, including Torreya taxifolia. In July 2007, Atlanta Botanical Garden decided to "back up" the precious original genotypes represented in their "potted orchard" (itself begun from branch cuttings from wild individuals in 1991) by rooting branch cuttings from each original genotype. By the time I visited ABG in December 2007, those cuttings had successfully rooted and had been transplanted into bigger pots and placed on the ground outdoors to ensure contact with micorrhizal fungi. ABG staff took me on a tour of their "misting room" (see photo below) and showed me examples of other gymnosperm branch cuttings in the process of being rooted. The cutting is scored with a knife in several places near the cut end; the end is dipped in growth hormone (3,000 to 5,000 ppm solution); no fungicide is used. The cutting is placed in a little pot in which a combination of pumice, perlite, and milled (ground-up) sphagnum moss entails the "soil" matrix. (Potting soil is only used after the roots have grown and the cutting is ready for transplanting). Note: You can acquire a supply of tiny pumice particles at a horse-stable supply company.
ADVICE FROM JACK JOHNSTON: A bit more about how Torreya can be rooted. The key is to keep the
cuttings at 70 degrees, but the air temp. can be cooler. A heated rooting
bed is used for this. A watertight "bench" maybe 6 inches deep is lined with
plastic to make sure it is holds water. A one inch layer of perlite is next.
Then a heating cable covered with hardware cloth 1/2 inch squares holds the
cable down. The bench has about three to four inches of coarse sand and
perlite mix on top of the hardware cloth. The mix is kept moist. Cuttings
are stuck after frost. A wire "canopy" well above the cuttings is used to
support a plastic drape. In a greenhouse the plastic is covered with shade
cloth. The plastic drape is lifted once a week all winter to check for moisture
in the sand/perlite and to add a little water if needed. Dead cuttings are removed.
Growth should be well along by April.
This system can be used in a basement with a grow light suspended over
the cuttings.
Part 2: Recommendations by Jack Johnston, based on his experience
propagating branchlets and seeds at his home in northern Georgia
Cuttings taken in Nov. 2009 after frost were placed in a closed plastic
container purchased at Walmart. Cuttings were about 3 to 4 inches
long. The container was partially filled with a mixture of perlite
and peat 50:50, watered, cuttings dipped in 0.8% hormone and
stuck in rooting media. The lid was snapped on the plastic
container to prevent moisture loss. The container was stored near
a basement window at 70 degrees. No additional watering was
needed as the cuttings rooted. Rooting was in progress when the
cuttings were checked 8 weeks later. It remains to be seen how
well the cuttings will grow.
Note: Seeds in an outside seed bed were checked. Voles were able to reach some seeds by digging under the wire-mesh-protected bed, and ate through the thin shells of the seeds much like a squirrel chewing into a nut. Remaining seeds were relocated to a vole-proof environment.
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LEFT: July 2008 photo of the protected outdoor bed where Jack planted in autumn 2007 T. taxifolia seeds he acquired. Notice the conifer-shape sprouts growing up through the mesh. Jack reported in January 2010 on the progress of these seedlings:
"Seedlings growing outside in the ground (from seeds harvested and planted in autumn of 2007) have reached a maximum of
9 inches after two years growth. Lime has been applied twice a year."
Note: Subsequently Jack has planted seeds in pots enclosed in a tight wire mesh "box" outdoors to forestall rodent predation. He also learned by experience that the perlite must be shaken out of rooted branchlets of Torreya before planting out into the yard. Click for September 2010 site visit captioned photos of Jack Johnston's methods of germinating, rooting and outplanting Torreya taxifolia.
2011 Note by Jack Johnston: "Two years ago I had seeds and planted them outside in Dec.
in one gallon pots with many slits down the sides. Drainage
was good. Germination occurred the first and second spring.
I have found that using pots is easier than dealing with voles
that get in seed beds.
Germination was excellent using
pots. After seedlings were a few inches high, they were moved
into individual pots."
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RECOMMENDATIONS FROM ARBORETUM DE VILLARDBELLE (2010): "From my experience with Torreya californica, the seeds will germinate whatever the temperature or the chilling period or even no
chilling period at all. I had seeds germinating while kept all the time in
the refrigerator or all the time at room temperature. The most important
factor as noted in previous messages is to keep the seeds moist.
The main question imho is to know wether the seeds are fertile or not. It
often happens with young trees that the pollination rate is not yet what it
will become with mature trees. My experience with Torreya californica shows
a germination rate of 70%. Of course local meteorological conditions at
pollination time plays an important role.
Rather than cuttings, I would suggest grafting on Torreya californica. The
problem with these kinds of propagation methods is that from what I could
see in Europe so far the plants will remain shrublike spreading
horizontally with no true leader."
Photographs of Torreya taxifolia Conservation Program
at Atlanta Botanical Garden
(Photos taken by Connie Barlow in December 2007)
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Photo A
Seeds (5 or 6 to a pot, coded by mother tree) are planted immediately after harvest in autumn and after the sarcotesta (fleshy skin) has been removed. Here, the inch of soil covering the seeds has been scraped away for viewing. |
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Photo B
Pots, like that in Photo A, have been set on the outdoor ground and covered with more potting soil. Here they will spend the winter, expected to germinate in April or May of the first spring. This location is in full shade beneath an evergreen canopy, and the pots are watered about every 5 days. |
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Photo C
The wire mesh hinged lid that protects the potted seeds has been shut, to protect the seedlings from being dug up by squirrels, who highly favor them. |
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Photo D
Ron Determann, director of plant conservation at Atlanta Botanical Garden, looks at Torreya taxifolia seedlings that sprouted from seed from the original genotypes in the garden's "potted orchard" that were produced in a series of different years. ABG is looking to distribute these and other seedlings (for free) to botanical and garden institutions who are interested in participating in the project to safeguard this highly endangered conifer native to northern Florida and southern Georgia. |
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Photo E
An outdoor holding area for various-age seedlings, awaiting replanting in native FL and GA habitat or shipment to participating institutions. Notice the black net canopy to protect the seedlings from too much sunlight and heat. |
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Photo F
Seedlings of Torreya taxifolia are sprinkled with lime (visible as white powder on soil surface) every 5 months or so, in order to guard against overly acidic soil conditions in which pathogens can get a hold. Notice that the pots are resting on outdoor soil, to encourage micorrhizal fungus associations. |
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Photo G
Misting room in which Atlanta Botanical Garden roots branch cuttings from imperiled gymnosperms and other plants, including Torreya taxifolia and Florida yew (Taxus floridana). |
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Photo H
In the misting room, a wide variety of gymnosperms and other plants are rooted from branch cuttings, such as those shown here. The "soil" matrix is white because it is made entirely of pumice, perlite, and ground-up sphagnum moss. |
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Photo I
The outdoor "potted orchard" of pollen and seed producing specimens of Torreya taxifolia, which were rooted in 1991 from branch cuttings taken from individuals still growing in native, wild habitat of northern Florida and southern Georgia. Notice that the potted plants are kept outdoors, underneath the shade of mostly deciduous oaks. Orientation means that these trees are subject to direct sunlight during summer afternoons. ABG staff speculate that ideal aspect for Atlanta habitat for this species would provide morning sunlight and afternoon shade, to protect the trees from the worst summer heat. They also speculate that placement on a slope of well-drained soil would be ideal. |
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Photo J
Even though this photo was taken in early December, male cones have already begun to form on branches of male T. taxifolia trees. Notice that the cones extend a ways down the branch stem. |
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Photo K
Even though this photo was taken in early December, female cones have already begun to form on branches of female T. taxifolia trees. Notice that the cones form very close to the tip of the branchlet. |
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Photo L
Atlanta Botanical Garden uses mesh "cages" to surround and thus protect the growing seeds on female T. taxifolia trees from plundering squirrels. These hang on one of the specimens in the "potted orchard" depicted in Photo I. |
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Photo M
After the seed harvest, wire cages that protected the ripening seeds from squirrels are stored for next year's use. |
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Photo N
One that got away: This seedling is growing right next to the fence in the "potted orchard" habitat. Because it is a volunteer, a squirrel must have gotten hold of a ripe seed, buried it, and failed to dig it up before germination the following spring. |
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Photo O
This is one of the 1991 "mother plants" (rooted branch cuttings from wild stock) that was planted outdoors in the soil, rather than kept in pots. ABG would prefer to plant all such original genotype specimens in the soil, but space limitations means that most are consigned to spending their entire lives in large pots. For this reason, the 1991 "potted orchard" specimens that are still in pots (a) had their branches cut back in the summer of 2007, and (b) were "backed up" by cloning the harvested branches, thus to ensure that even if the original stems die, the exact genotypes are still available in a new generation of potted plants. |
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Photo P
This is a close-up of the stems of the plant in Photo O above. Notice that no single vertical trunk is growing. This haphazard growth form is typical of specimens that began life as rooted branch cuttings. Only specimens that are grown from seed have the capability to develop trunks and grow into tall trees. The advantage of using rooted branch cuttings rather than seeds, however, is that rooted branch cuttings will themselves begin producing male or female cones much earlier than will specimens grown from seed. |
Fabulous photos of a germinating Torreya seed at Arboretum de Villardbelle website.
Smithgall Woods 2007 seed harvest sprouting
in northern Georgia (home of Jack Johnston).
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Torreya sprouts. (Mesh deters squirrels from seeds.) |
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