Metasequoia glyptostroboides update, and future plans.

Back in April I wrote about germinating some Metasequoia, or Dawn Redwood, seeds. In all, five seedlings germinated. The tallest of these grew to about ten inches, while the smallest two are around six inches. I had planned on posting an update back in August, but actually working in the garden took precedence. But I did take a photo before moving the potted seedlings to a sheltered location outdoors.

Metasequoia glyptostroboides seedlings, August 2014.
Photo by Bill Jury.

As you can see from the photo above, even the smallest of the five seedlings was doing well. The pot in the upper right actually has two seedlings that I have yet to separate, but there's still room in the pot (I'll separate them in the spring). These spent the remaining days of August, September, and most of October - basically until our first hard freeze - in a lightly shaded location outside. In late October, on the evening of our first serious freeze, I pulled the seedlings into our insulated garage. A cold frame would be better, but the garage window works for the time being. At this time the largest seedling has dropped much of its foliage, the next two largest are somewhere in between, while the smallest two are still holding on to their needles. Otherwise, all five of the seedlings show healthy, dormant buds ready for the warmth of next spring.

Metasequoia on the San Jose University Campus.
Photo by John Pozniak.

The future? As I wrote back in April, this is a big tree, but I am working on preparing a spot for one toward the back of the garden. If all goes as planned (a big "if" when gardening in Colorado), I might eventually have the tallest tree in Milliken!

Kiwano Melons.

I'm always interested in trying new fruits, so for my birthday last month my wife got a Kiwano Melon for us to try. It looks like something from another world, so much so that Star Trek: Deep Space Nine used them in the episode "Time's Orphan" (repurposed as "Golana Melon"). Covered with several hard, horn-like spikes, the Kiwano Melon, known scientifically as Cucumis metuliferus, turns a radiant orange when ripe. This contrasts with its pale-lime flesh. Kiwano Melon, in the Cucurbitaceae family, is related to cucumbers and gherkins, and the flavor of its flesh typically includes "cucumber-like" as a descriptor. I say includes because, in addition to hints of cucumber, I also tasted green banana and citrus. Deborah and I enjoyed it, but Corran wasn't too sure about the texture (as one source writes, "the pulp resembles lime-green Jell-O"). Still, he ate it...but, aside from unsweetened lemon, Corran hasn't met a fruit he hasn't liked.

Fruit of Cucumis metuliferus, the Kiwano Melon.

Cucumis metuliferus is an annual vine native to Africa and is cultivated as a traditional African food. It, along with the Gemsbok Cucumber (Acanthosicyos naudinianus), is a significant - some say only - source of water during the Kalahari Desert's dry season. When eaten fresh, most people suck out the pulp and spit out the seeds, though the seeds themselves are also edible. I saved ten of the seeds and planted them in starter pots. After all, if Kiwano Melon will grow as a crop in New Zealand and California, Colorado should have plenty of heat and sun. And, since our growing season is long enough for other melon crops, there should be more than enough time for the Kiwano Melons to ripen. I wasn't even sure if the seeds would be viable, but they were.

Growing Cucumis metuliferus trellised as a vine is the recommended method, but you can let it grow along the ground. Given its desert origins, Kiwano Melon prefers infrequent watering; allow the soil to dry out between waterings. It grows fast, so I am going to have to design and install some trellises before too long. But it will be worth it!

If you're interested in growing a Kiwano Melon, and you can't find one in your local market, Baker Creek Heirloom Seeds sells packets of this and other unusual edibles and ornamentals.

The first sprouts of Ribes aureum and Shepherdia argentea.

A few days ago the first Shepherdia argentea, or Silver Buffaloberry, began germinating. This native fruit has the potential to grow to almost 20 feet in height with a spreading crown of equal size - much larger than its native cousin Shepherdia canadensis (Russet Buffaloberry). The fruit, a red fleshy drupe with a variable taste, was used historically by several Native American peoples as food, medicine, and dye. Many report that the fruit is bitter, but this is attributed to the presence of saponins; frost reportedly causes the sugar content to increase, improving the flavor. In any case, Silver Buffaloberry is drought-tolerant and, with pruning and shaping, can make a beautiful large shrub or small tree with silver-green leaves. Of course, like many native fruits, Shepherdia argentea is armed with impressive thorns. The fruit is mealy and considered edible, not necessarily delicious. However, its value from an ethnobotanical perspective (not to mention its drought-tolerance) makes the Silver Buffaloberry well worth the time and effort to grow it.

Shepherdia argentea. Photo taken at Chief Whitecap Park
in Saskatchewan, Canada by SriMesh.

This morning I also noticed the first of the Ribes aureum, or Golden Currant, sprouting. I hope to see more germinating in the next few days. This is another native fruit; the clove-scented yellow flowers are the source of its common name. Ribes aureum is considered one of the most delicious of the wild fruits adapted to our region. Unlike Shepherdia argentea, Ribes aureum is thornless. Though tolerant of moderate shade, it prefers moist soil in full sun. Typically three to six feet tall, the Golden Currant can grow even taller under optimal conditions. The berries, appearing on short racemes from the leaf axils (the base of the leaf at the stem), ripen from mid to late summer, turning a deep black or black-purple color. I am looking forward to establishing a small thicket of Golden Currant this year!

Ribes aureum. Photo by Stan Shebs.

Germinating Yucca elata and Yucca faxoniana.

Last year I sprouted several Yucca baccata (Banana Yucca) and Yucca elata (Soaptree Yucca), and while I grew out many Yucca baccata, I only managed to grow out a single Yucca elata. Despite our brutally frigid temperatures, this single Soaptree Yucca handled the Colorado winter seemingly with ease. This is encouraging - the tree yuccas fascinate me, which naturally means I plan on growing some more.

Today I began cold-stratifying eight Yucca elata seeds and eight Yucca faxoniana (Texas Tree Yucca) seeds. Yucca elata is probably the hardiest of the tree yuccas, but success with yuccas, agaves, and their kin is determined by many factors, and USDA hardiness zone is only one of these. Siting (soil structure, exposure, microclimate, etc.) seems to be as critical in determining success with members of the family Agavaceae, particularly when planting them in areas pushing the limits of their cold-tolerance. My Yucca elata is growing on an exposed bed of decomposed granite, granite chunks, pumice, and loam-amended clay (the native soil). Since our regionally native Yucca glauca (Soapweed or Great Plains Yucca, a short colony-forming species) thrives in our local soil, I'm not surprised that its relatives have done well either. Still, since many reputable sources cite Yucca elata as hardy to "about zone 6a", I am very pleased that our less-than-a-year-old seedling survived the winter. Yucca elata has a reliable branching habit, adding to its "tree" image.

Yucca elata blooming. Photo by Stan Shebs.

Yucca faxoniana - the Texas Tree Yucca - is the other tree yucca that I am attempting to propagate. This hardy tree yucca has one of the thickest, stoutest trunks (a foot in diameter) that supposedly forms a single stem reaching a mature height of up to 15 feet. I am following a similar protocol for cold-stratifying the seeds (about a month), since it seems that yuccas benefit from cold-stratification even if they are native to a milder clime. Some sources claim that Yucca faxoniana is hardy to USDA Zone 5, while others are far more conservative (USDA Zone 8), so I will just have to grow them out and see. My source claimed it was hardy to USDA Zone 5. As I wrote earlier, it seems that Yucca faxoniana is similar to Agave parryi in that differing populations of the same species can have quite different hardiness limits depending upon the conditions of their native environment. Perhaps my seeds come from a hardier population. We'll see. I plan on growing these near my Chilopsis linearis (Desert Willow) in a protected, sunny location that warms to daytime temperatures quickly in the winter.

Update 04-23-2014: I was able to read the section in Mary and Gary Irish's excellent book Agaves, Yuccas, and Related Plants on Yucca faxoniana and they indicate that it can tolerate severe cold - a relative term here in Colorado - down to approximately 0 degrees Fahrenheit. We frequently get a tad colder, but I still think siting will play a factor in its success or failure.

Yucca elata with Yucca baccata in the upper right.
Photo by Bill Jury.

I also managed to get a photo of my Yucca elata yesterday. It is putting on new growth and has very little winter damage. Not too bad for a year-old seedling.

Grass trees and ginkgo.

A few days ago I received a grafted year-old Ginkgo biloba 'Mayfield' from Kigi Nursery. This happened to coincide with one of Colorado's late-Spring cold spells, so I simply potted the little tree up. Besides, the ginkgo hasn't broken dormancy yet, so forcing it to wait for warmer weather shouldn't really be an issue. For those unfamiliar with this particular cultivar of ginkgo, 'Mayfield' is an upright columnar form, and it is probably the narrowest in cultivation. Introduced from Ohio in the 1940's, Ginkgo biloba 'Mayfield' is not as well known as 'Princeton Sentry', but it is the perfect specimen tree for our small, commensurately narrow yard.

Ginkgo, of course, is precisely the sort of tree one would expect to find in Sir Arthur Conan Doyle's "Maple White Land" from The Lost World. It is a survivor, a relic from the early Jurassic; other ginkgo-like fossils date to an even earlier era. Ginkgo biloba was discovered by naturalist Engelbert Kaempfer in China, as so many of our "living fossils" have been, in 1691; over 400 years later, this sole-surviving ginkgo species now has a cosmopolitan dispersal as an ornamental tree with an ancient lineage. Botanist Peter Crane has written an excellent, comprehensive natural history of the ginkgo tree in Ginkgo: The Tree That Time Forgot (Yale University Press, copyright 2013). If you're interested in the story of this incredible survivor, then this is the book for you.

Just a couple days ago, after almost two months, the first Xanthorrhoea australis seedlings poked their pointy leaves out of the soil. As of this moment, six of the eight seeds appear to have germinated, which is a better ratio than I anticipated. Actually, I had started to wonder if the seeds were viable, or if I'd used an appropriate soil blend in which to germinate them. I guess I should have known that some seeds just take longer to germinate. As their name implies, these seedlings look for all the world like a tiny sprout of grass...perhaps with blades a bit more stiff and thick, but grass nonetheless. It will take as long as twenty years before Xanthorrhoea australis develops its characteristic trunk. I will try to post a picture of the seedlings in the near future. But, as I tell myself, this is what these will look like one day:

Xanthorrhoea australis. Photo courtesy of Australian Seed.

I borrowed this photograph from Australian Seed. They do ship internationally, according to their website, so if you can't source this amazing plant domestically, perhaps give them a try. It looks like Australian Seed carries the seeds of many other native (and unusual) Australian plants, so keep them in mind for these as well (I know I will). And, while the Ginkgo is a far better-known Mesozoic survivor, the family Xanthorrhea is ancient as well - it is possible that the Cretaceous saw the first Grass Trees growing in the soil of a fractured Gondwana.

Ephedra nevadensis and cold-stratification.

Last night I began cold-stratifying a small flat of six to eight Ephedra nevadensis. I have promised myself I will leave them in the refrigerator for the requisite 30 days. Unfortunately, the single seedling I managed to propagate last year appears to have succumbed to the elements (namely, my own distraction - it was not with my other seedlings and I missed watering it). A small pot in an arid climate can kill a seedling of even very xeric-adapted plants. It's still possible that the seedling is simply dormant, since they grow very slowly, but maybe not. Gardening is a learning experience, even if the learning curve is sometimes steep.

I also ordered packets of Ephedra intermedia and Ephedra equisetina (Bluestem Joint Fir), and I look forward to propagating these as well.

A reliably hardy palm for Colorado!

Yucca rostrata.

Okay, not really. But the tree yuccas are really cool, and Yucca rostrata 'Sapphire Skies' has a very tropical feel. Its upright habit and rigid leaves make it a striking specimen in the garden. 'Sapphire Skies' might be slightly hardier than the species. Its leaves are stiff, shorter than the species, and, according to Monrovia, "form a dense crown atop an elegant single trunk." Like most yuccas, Yucca rostrata is slow-growing, but it is likely one of the hardiest tree-like yucca species...and it is certainly one of the most beautiful. On the issue of hardiness, siting seems to be a significant contributor to success or failure. Depending on the source, Yucca rostrata 'Sapphire Skies' is hardy to USDA Zone 5b, while the species seems to be hardy to USDA Zone 6. Again, proper siting is key. Its soil should drain well and it should be in a location with full sun. In Colorado's dry climate, this would be an excellent candidate for the tropical garden.

Yucca rostrata 'Sapphire Skies'.
Courtesy of Monrovia.

Other hardy tree-like yuccas includeYucca elata, commonly called the Soaptree Yucca (hardy to USDA Zone 6a, though mine sailed through temperatures that dropped below -10 Fahrenheit this past winter), and the compact form of the famous Joshua Tree, Yucca brevifolia v. jaegeriana (reportedly hardy to USDA Zone 5). Even the standard form of Yucca brevifolia is hardy to USDA Zone 6a. Yucca torreyi (reportedly hardy to USDA Zone 5), Yucca faxoniana 'Giant Faxon' (from the northern population of the species, reportedly hardy to USDA Zone 5, though other sources indicate the species is only hardy to Zone 8; perhaps Yucca faxoniana is similar to Agave parryi, where different populations and subspecies can vary wildly in hardiness, but I digress), and Yucca schottii, the Mountain Yucca (hardy to USDA Zone 6a or maybe Zone 5b) are a few others that might prove marginal in Colorado but would work great in the right microclimate. Many of these species appear far more at home in an arid desert landscape, but Yucca rostrata lends itself to either the tropical or the desert garden, as would a mature grove of Yucca schottii. With marginal yuccas, perhaps the only way to know if a species is hardy in your garden is to try growing it. It is definitely worth it - these are amazing plants!

Yucca schottii. Photograph by Georges Jansoone.
This specimen looks for all the world like some species of Pandanus, minus the prop roots.