The Serbian spruce, Picea omorika ‘Blue Sky’ is looking lovely at the base of the Mt. Michelle waterfall this week. We think the color of the spruce foliage nicely echos the nearby agave–a combination you won’t see in most gardens. We’re always on the lookout for more spruces that tolerate our heat and humidity.
The foliage of Asphodeline damascena is looking absolutely wonderful…like a blue beetle’s wig from the 1960s. This little-known member of the Asphodel family hails from the dry deserts of Turkey and Syria/Lebanon. Other current members of the family include the genus Aloe, Haworthia, Hemerocallis, and Kniphofia. The short spikes of white flowers will appear soon, but we’d be happy if this never flowered.
A couple of years ago, we were thrilled to acquire seed of Euphorbia ‘Rubicund’ from the Hardy Plant Society seed exchange. That little-known clone is a selection from a cross of Euphorbia myrsinites x E. rigida made by Rhode Island’s Issima Nursery. While the clone doesn’t come true from seed, we love our offspring and look forward to seeing what our seed crop from the plant below will have in store.
For this hybrid, we’ve settled on the nothospecific name E. x myrsida, going forward. Over 15 years ago, we acquired a similar cross from California salvia guru, Betsy Clebsch, but we unfortunately let our plant get shaded out. Both plants we’ve grown of this cross produced much larger seed heads with a form similar to both parents. It has been stunning in our our rock garden for the last month. Hardiness is probably Zone 6a-8b.
Several plants emerge in the fall/winter season…some native, and others from far away Mediterranean climates. One of the most unusual plants we grow is the pig’s butt arum, Helicodiceros muscivorus. Depending on the location of the original population on one of the Mediterranean islands, it can emerge in our climate as late as February or as early as December. Here is a photo of our plant of an Alan Galloway collection from Majorca, which is the earliest to emerge in our garden. Let’s hope it’s ready for our upcoming cold snap. Even if this never flowered, we marvel at the glaucous, three-dimensional Escher-esque foliage.
As fall temperatures drop, it’s not unusual to find our native bees asleep in some of the most interesting places. We caught this carpenter bee fast asleep on the job this week, clinging tightly to the spines of an Agave parryi.
We have a fairly decent collection of conifers at JLBG, but one that has really caught our eye is Chamaecyparis pisifera ‘Baby Blue Ice’. This charming dwarf was found in 1998 by Oregon nurseryman Larry Stanley as a sport of Chamaecyparis pisifera ‘Baby Blue’. Our oldest plants are now four years old and are 3′ tall x 2′ wide. The naturally dense growth and conical shape give the impression that it’s been sheared, which is not the case.
Word on the street is that it should mature around 6′ tall, but with newly discovered plants like these, we take those size predictions with a large grain of salt. Undoubtedly, mature size in the Southeast US will be quite different than in the heat-deprived Pacific Northwest.
There is a “growing” trend toward using groundcovers to reduce the need for bark mulch in gardens. As with any trend, there is a time and place where it is appropriate, and other times when it is not. One plant that we absolutely love for that purpose is the evergreen Carex flacca ‘Mini’. This blue-foliaged sedge is a Mediterranean native marsh grass that spreads very slowly, so it is not a problem in overrunning other plants in the bed, as long as they aren’t placed too close. These pictured below were planted six years ago on 1′ centers, and are just now knitting together.
We have studied a few reports of this sedge being invasive in parts of the northeast US, but our trials have shown quite the opposite, with nary a seedling in over six years. We can find no scientific research that shows this sedge qualifies as being invasive using any commonly recognized definitions of an invasive plant. Our skepticism of these reports comes because some of the ridiculous listings that appear on invasive species lists, which have no scientific basis. Our favorite invasive faux pas was a listing a couple of years ago of the genus Bambusa on a state invasive list. Never mind the plant is a strict clumper and only flowers once every 100 years. Winter hardiness is Zone 4-9.
Our tallest clump of Nelson’s bear grass has been in full flower for the last month, making a spectacular site. Our specimen, which has reached 10′ in height is now 23 years old from seed. This woody lily which hails from the state of Tamaulipas in Northern Mexico forms a yucca-like stalk in the garden. All of the other hardy bear grasses have green foliage, so the blue foliage of Nolina nelsonii is quite distinct. The common name of bear grass was coined on the Lewis and Clarke expedition, when nolinas were mistaken for yuccas, which at the time were known as bear grass. Hardiness is Zone 7b-10b.
If you’re able to visit during this years spring open house, it will be hard to miss the look of love in the air. We have a record 20 century plants in spike in the garden…a number far surpassing any flowering record we’ve set previously.
Agaves are a genus of mostly monocarpic plants…they live their entire lives to flower once, then after experiencing a giant-sized orgasm, they fall over dead. In the wild, many species take up to 100 years to flower, which is why the name century plant stuck as a common name. In our more rainy climate, our century plants typically flower in 12-15 years. Several of our current crop are actually less than a decade old, but their enormous size has already been achieved, so they’re ready to reproduce.
Some species of agaves offset, and in this case, only then central rosette dies, and the offsets continue as is the case with bromeliads. Those agave species which never offset are one-and-dones, but hopefully will leave behind a plethora of seed for the next generation. From the start of the spikes to full flower is usually about 8 weeks. Below are a few of our babies in spike.
For years, we struggled to grow the Mediterranean/Balkan native spurge, Euphorbia characias…until we discovered its secrets. First, it isn’t a long lived plant to begin with…in most cases 3-5 years is it, so you’ll need to plant it where it’s likely to reseed. That would be well-drained slopes that are either mulched or covered with gravel.
Secondly, after it flowers in spring with its stunning show of yellow flowers, remove most of the flower stalks as soon as flowering has finished, except those needed to produce new seedlings (the flowers are also great to use in floral arrangements). If not, the seed stalks use up energy causing the plant to decline much faster. We’ve now allowed this to seed throughout the slopes in front of our house, and here is the result…a smattering of 3′ tall x 3′ wide clumps, photo taken mid-winter.
Although this section of the garden, planted in compost-amended sandy loam is irrigated, we typically don’t recommend irrigation for this spurge without excellent drainage. You’ll also read on-line that Euphorbia characias doesn’t like hot, humid summers…another example of fake gardening news that just keeps getting repeated without any concern for the facts.
We’ve also found Euphorbia characias to grow well in part sun under large trees, which keeps the soil dry. The plants will never be as dense as they are in full sun, but they survive and flowers. There is really not anything else that gives you this evergreen blue color and form in the winter garden.
We love our Mediterranean blue fan palms…one of the coolest palms we can grow outdoors. We’re right on the edge of winter hardiness for Chamaerops humilis var. argentea, so the key is to grow it to a larger size before planting in the ground. We’ve lost a few that we planted too small, and when that planting coincided with a cold winter.
This is a photo taken this January of our oldest clump, now 17 years old. This is a very slow growing palm, so a good bit of patience is required when getting it established. When we do experience single digits F winter temperatures, all of the foliage is burned back, but it re-sprouts from the base in spring. Mediterranean blue fan palm hails from high elevations in the Atlas Mountains of Morocco, where it eventually makes a 15′ tall specimen. In our cold winter climate, we doubt it will ever top 4′ in height. It should be winter hardy from Zone 7b and warmer.
One of many great attributes of mangaves, compared to one of their parents, agaves, is that they don’t die after flowering. Agaves are mostly monocarpic, which mean that they behave like bromeliads, where each rosette grows to maturity, then dies after flowering. Those species of agave which offset, live on after flowering, by means of un-flowered offsets. Those agave species which don’t offset are a one and done after they flower and reproduce by reseeding.
By incorporating manfreda genes to create xMangaves, the monocarpic trait disappears. After a mangave flowers, it dies to the ground, but like a good zombie, it soon pops back from the dead. Here is a current photo from the garden of two clumps of xMangave ‘Blue Mammoth’. The first, larger clump has not flowered, but should do so next year. The second clump with all the offsets, flowered in 2020, and re-grew to this point in 2021. Next year, the rosettes will continue to re-grow in size.
We’ve been experimenting to see how many species of asclepias will survive in our climate, and one that has been quite fascinating is Asclepias subulata. This odd species from the southwest deserts of the US has evergreen glaucous stems, and not much in the way of leaves. It will be quite interesting to see what the butterfly larvae actually consume. It did flower for us this fall for the first time. This will be our first winter, so fingers crossed it can take our cold and wet temperatures. We sited this on a slope in one of our crevice gardens, so it wouldn’t drown in our summer rains.
Since we are limited in the number of hardy century plant species, our only option for more agave diversity in the garden is to create it by crossing existing hardy species together. Here are a few of our recent successes.
Agave x amourifolia is a Plant Delights/JLBG creation from a cross we made in 2016 that combined the genes of three century plants, Agave ovatifolia, Agave lophantha, and Agave x pseudoferox ‘Logan Calhoun’. Our size estimates were that the offspring would mature at 3′ tall x 5′ wide. Here is one of our garden specimens photographed this week, which has already reached 2′ tall x 3′ wide.
Below is Agave x ovox, a 2017 cross of the two giants, Agave ovatifolia and Agave x pseudoferox ‘Bellville’. We expect this to get huge…perhaps 5′ tall x 10′ wide.
Below is Agave x protifolia is a 2016 Mike Papay cross of Agave x protamericana x Agave ovatifolia. We also expect this to get quite massive.
Below is Agave x ovatispina ‘Blue Arrows’, a 2016 Mike Papay cross of Agave ovatifolia x Agave flexispina. We would have expected this to be a mature size, but it’s achieved this in only 5 years, so we think we’re seeing some serious hybrid vigor.
Below is Agave x ocareginae, our 2016 cross of Agave ovatifolia x Agave victoriae-reginae. Most likely, this elegant small grower will never offset.
Below is Agave x schuphantha, a 2015 Mike Papay cross involving three century plant species, Agave schidigera, Agave lophantha, and Agave lechuguilla. It’s formed a beautiful, symmentrical rosette, which should be getting close to mature size.
No, we’re not talking about your favorite football or basketball team, but the amazing blue Mediterranean fan palm. Here’s our oldest (16 year) specimen in our alpine rock garden this week. Chamaerops humilis is a Southern Europe native that’s marginally hardy in our region, but the blue form, know as var. cerifera (or var. argentea). is much more tolerant of our cold winters. If our winter temperatures drop into the single digits F, the foliage dies back to the ground, but quickly rebounds in spring.
At our home, we have a very wide overhang which never sees any moisture, so we were looking for plants that would stay low, ideally evergreen, and would tolerate seriously dry shade. The answer was Echeveria ‘Topsy Turvy’. These patches of the Northern Mexican succulent, with blue-green foliage, have absolutely thrived here. While they probably wouldn’t be happy in deep shade, they love this high canopy with good light, but no sun. These were planted in 2018. We’d rate these as Zone 7b/8a if kept dry in winter.
One of our favorite blue-foliage conifers that thrives in the southeast heat and humidity is Cupressus arizonica var. glabra ‘Blue Ice’. This is a four year old planting of the Arizona native that’s already made a nice size specimen. Cupressus ‘Blue Ice’ is great to use for Christmas arrangements, due to it’s color, foliage fragrance, and ability to hold up very well after being cut.
