Green Bean Pole

We have been very impressed with the very narrow selection of our East Coast native arborviatae, Thuja occidentalis ‘Brobeck’s Tower’. This has been in the garden now for 4 years, and is 6′ in height and just over 1′ in width. This seedling selection was made by Sweeden’s Anders Brobeck, where the same plant takes 20 years to reach this height, due to a lack of summer heat.

Thuja occidentalis ‘Brobeck’s Tower’

Tough Love Child

We were thrilled to see most of our plants of Trichocereus ‘Love Child’ come through the 11 degrees F unscathed. We hope to have enough of these in the next year or two to share. We had long wanted to grow and offer some of the ridiculously large flowered, tacky colored tropical trichocereus cactus, but they simply had no winter hardiness.

Enter our former volunteer curator, Mike Papay, who had the same idea, but was more determined to make it happen. Mike worked with Trichocereus bruchii, and the resulting second generation plants yielded one he named Trichocereus ‘Big Time’.

He created another winter hardy hybrid using Trichocereus bruchii and Trichocereus thelogonus that he named Trichocereus ‘Iridescent Watermelon’. We subsequently crossed both of Mike’s hybrids together to create a seed strain we named Trichocereus ‘Love Child’. Below is one of our garden plants after enduring 11 degrees F. Below that is the same plant in flower last spring. Hardiness zone 7b to 10b.

Trichocereus ‘Love Child’
Trichocereus ‘Love Child’

The Little Asparagus that Could

In 2006, NC plantsman, and our long time customer, Graham Ray of Greensboro, emailed to see if we were interested in a dwarf Asaparagus densiflorus (Sprengeri) fern that he grew in his rock garden, and had been winter hardy for several years in his Zone 7a garden.

We had already worked with several asparagus species for years, and have a great fondness for the ornamental potential of the genus, so of course, we jumped at the opportunity. We were perplexed, however, how a dwarf version of the marginally hardy Asparagus densiflorus could have survived in Greensboro, which is a 1/2 zone colder than our garden south of Raleigh.

Despite our skepticism, we planted our new treasure in fall 2006, which thrived here, despite our winter hardiness concerns, not blinking during three upcoming single digit F winters. A few years later, we sent a plant to our friend Hans Hansen at Walters Gardens in Michigan for further testing. Despite their winter temperatures well below 0F with no snow cover, it thrived there also. What was going on, we wondered, since this simply shouldn’t be possible.

A mature plant of the dwarf asparagus fern, 'Graham's Cracker' growing in our rock garden.
Asparagus ‘Graham’s Cracker’

Our mystery was finally resolved this summer when taxonomy researchers from the University of Georgia, working on the phylogeny of the genus Asparagus, learned of our extensive collection of Asparagus species, and came by to take samples for their research. This fall, we got word that our dwarf plant which we had named Asparagus ‘Graham’s Cracker’, was in fact not a selection of the common hanging basket species, Asparagus densiflorus, but was instead a seedling of the Zone 4 hardy Asparagus cochinchinensis.

As we re-traced the plants origin, it turned out that Graham had purchased the plant here at Plant Delights, as a dwarf seedling he found in one of our sale house flats, which our staff had failed to notice.

Above is a photo of a mature plant of Asparagus ‘Graham’s Cracker’ at JLBG, which has finally reached a whopping 15″ in height…a perfect plant for the rock garden or in larger bedding schemes. Like the species, the fall foliage is a brilliant gold.

Asparagus ‘Graham’s Cracker’ in fall

And here’s mama, Asparagus cochinchinensis ‘Chuwang’.

Asparagus cochinchinensis ‘Chuwang’

Precious Metals…Investing in Silver

We have been fascinated with hardy cyclamen since the 1960s, but in recent years have spent a bit of time isolating some of the best silver-leaf variants that showed up in our seed pots and getting these established in the garden. These silver leaf oddities can be found in the wild, although they are fairly rare. In cultivation, however, they come fairly true (50%) from seed.

Through Plant Delights, we offer these as seed strain cultivars, under the names below…when available. A new crop of cyclamen will go on-line January 1, and there are some real beauties. Here are some images from the garden this week. Winter hardiness is Zone 4a-8b.

Image of Cyclamen hederifolium 'Silver Cloud' in the garden
Cyclamen hederifolium ‘Silver Cloud’
Image of Cyclamen hederifolium 'Silver Swan' in the garden
Cyclamen hederifolium ‘Silver Swan’
Image of Cyclamen hederifolium 'Silverado' in the crevice garden
Cyclamen hederifolium ‘Silverado’

Makin’ Mangaves

While we leave all the fancy mangave creations to our friend Hans Hansen at Walters Gardens, we continue our work on creating more winter hardy (to 0 degrees F) hybrids. Over the last couple of years, we’ve made several crosses using some of Hans’ hardiest Agave ovatifolia based F1 generation selections, like xMangave ‘Blue Mammoth’ and xMangave ‘Falling Waters’ and crossing them back onto Agave ovatifolia.

The F1 mangave hybrids from Hans’ work, have all lost the monocarpic trait of pure agaves, meaning they will not die after flowering. We are curious what will happen if the hybrids have 2 parts agave and one part manfreda. With most of our crosses, we grow 100-200 of each into 1 qt pots, which allows us to do an initial culling after seeing the juvenile foliage traits.

The photos below are from that process, which happened this week. This is a cross of xMangave ‘Falling Waters’ x Agave ovatifolia ‘Frosty Blue’. The first image shows the diversity in the seedlings. All plants have some degree of glaucous foliage…some more toward blue and others with purple spotting that comes solely from the Manfreda parent. It was interesting that the F2 plants still showed some degree of purple spotting…probably around 5% of the plants.

Mangave seedling variability within a F2 generation cross.
x Mangave ‘Falling Waters’ x Agave ovatifolia ‘Frosty Blue’

From a batch of 100-200 plants, our goal is to select 10% for the next round of in ground trials. We focus on selecting at least one plant for each desirable trait. Those traits include: size (dwarf or large), leaf undulations, spotting density, best blue color, leaf twisting, leaf length, leaf width, overall form, best spination, and variegation.

Below are some of our final selections for the next phase of trials. These will be up-potted into 3 quart pots and overwintered indoors, since we’re already too late for planting outdoors this year. These will go into the ground in spring, after the danger of frost has passed.

Mangave seedlings selected for in ground hardiness trials.
x Mangave ‘Falling Waters’ x Agave ovatifolia ‘Frosty Blue’
x Mangave and Agave hybrids overwintering in a heated greenhouse
x Mangave and Agave hybrids overwintering in a heated greenhouse

That won’t grow here!

I wish I could count how many times we’ve been told, “That won’t grow in your climate.”. Our contrarian streak has led us down many interesting paths, with quite a number of surprising results.

The most recent is Chrysophyllum oliviforme. Over a year ago, we planted seed grown plants, native to the recently hurricane-ravaged Sanibel Island, Florida. This species is native to Southern Florida, the Bahamas, the Greater Antilles, and Belize. With that distribution, it should have no chance in our winters, but, despite die back during last winter’s low of 16F, it returned, and is now approaching 4′ in height. I should add that our plant was planted on a very exposed site, with no protection.

Is it going to be a long-term plant….probably not, but there is obviously more winter hardiness than most informational sites would lead us to believe. I should add that we planted two seedling, and the other one planted nearby, succumbed to the winter temperatures. If you never take risks, you’ll rarely get to experience the joy of amazing surprises like these.

Chrysophyllum oliviforme
Chrysophyllum oliviforme

Monroe’s Monkey Grass

I wonder if the late Atlanta nurseryman, W.L. Monroe had any idea what would become of his white-flowered monkey grass, that he selected as a seedling and subsequently introduced to the gardening world in 1957?

In the 65 years that’s passed since it’s introduction, Liriope muscari ‘Monroe White’ is still the gold standard by which all white-flowered liriope are judged. Here are our plants flowering this week at JLBG. Unlike most liriope, which thrive in sun, this cultivar needs light shade for most of the day to prevent foliar scorch. Our plants in the photo only get a couple of hours of direct sun, where they thrive. Winter hardiness is Zone 6a-10b.

Image of Liriope muscari (monkey grass) 'Monroe White' flowering
Liriope muscari ‘Monroe White’

False Larch

We’ve long had an affinity for larches (probably due to a hangover from watching the Monty Python larch skit far too many times), but there aren’t many larches that will survive our hot, humid summers. We can, however, succeed with the false larch, which belongs to the monotypic genus, Pseudolarix. Both larix (larch) and pseuodlarix (false larch) are deciduous conifers, whose foliage turns golden yellow in fall prior to leaf fall.

Pseudolarix is known as an open, airy species, and having seen quite a few over the last 50 years, all were very similar. Imagine our surprise, when a new seedling we purchased in 2017 turned out to be incredibly dense and fast growing. The first photo is our oldest typical pseudolarix, now celebrating 29 years in the garden.

The new clone, which we’ve named Pseudolarix ‘Greensanity’, just 5 years in the garden, is pictured below that. We look forward to working with some woody plant nurseries to get this exceptional form grafted and into the trade.

Pseudolarix amabilis - typical false larch at JLBG
Pseudolarix amabilis – typical form at JLBG

Pseudolarix amabilis 'Greensanity'
Pseudolarix amabilis ‘Greensanity’

Very Variegated

This spring, one of our flats of Rohdea japonica seedlings turned up with an inordinate number of variegated seedlings. In a flat of approximately 1,000 seedlings, we typically expect 3 – 10 variegated offspring, when the parent plant has white streaking in the middle of the leaf (L2 layer).

All of the variegated seedlings were removed and potted individually last week…all 300 of them. It will be fascinating to see what unique forms result.

Gussied up Ostii

One of our Paeonia ostii seedlings flowered well for the first time this year, and turned out to be semi-double flower instead of the typical single flowers. We’ll continue to observe it in future years and make sure the trait is stable, but if so, this could be a lovely addition to the world of hardy tree peonies that tolerate heat as well as cold.