Flowering in the garden this week is the fascinating, but little-known Houstonia procumbens. This Southeastern US coastal native (South Carolina west to eastern Louisiana) is a spreading, winter flowering bluet. We collected cuttings in Clay County, Florida in 2003, and this patch has been thriving in our sunny alpine garden since then, forming a 1.5′ wide patch.
Juniperus communis is a common landscape juniper with a wide natural distribution…one of the widest of any woody plant in the entire world.
In the North American part of its range, it’s widespread throughout the Western US, and across the northern tier of the country all the way to Maine. East of the Mississippi River, however, it’s virtually not-existent south of the Great Lakes.
Patrick McMillan had been telling us about a population he rediscovered from an earlier Henry William Ravenel (1814-1887) documentation of a single clone growing naturally in Aiken, South Carolina. Last week, we made the 4 hour drive to visit this ancient living fossil. Here is all that remains, growing in an amazing nature park, known as Hitchcock Woods, where it grows surrounded by a forest of Kalmia (mountain laurel).
We have this propagated and growing at JLBG, and hopefully in the future, when our plants get larger, we can share these amazing genetics with a wider audience.
Ajuga ‘Parrot Paradise’ is one of many new next generation colorful ajuga groundcovers that have hit the market in the last few years. These have been amazing in our trials, as you can see from the October photo below. Best of all, we haven’t seen any seedlings, which have been a problem with several of the more common clones in commerce. We think both the color and growth habits are truly outstanding.
With the trend for green mulch (i.e. groundcovers), we continue to trial a number of new introductions that fit the bill. One of the top performers continues to be Sedum ellacombeanum ‘Cutting Edge’ PP 28,926. This 2016 Brent Horvath introduction has thrived in both sun and light shade, making a perfect ground-hugging mat. Despite being a top performer, sales were miserable when we offered it a few years ago. We’re not sure why it sold so poorly, but we now have some lovely drifts in the garden.
We love the miniature silver mats of Antennaria parviflora (little-leaf pussytoes). This little-known North American native (Canada south to Arizona) forms a tiny, 1″ tall groundcover that’s hard to the touch. In spring, the patch is topped with short fuzzy spikes of brush-like white flowers. The plant below, which measures 1′ in width, is only 18 months old from seed, and is growing in our rock garden in a well-drained mix of 50% Permatill. Hardiness is Zone 4b-7b.
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.
One of the most amazing summer perennials we grow is the native Berlandiera pumila ‘Chocoholic’. It is unfathomable to us, why this isn’t grown in every full sun garden where it’s winter hardy. The flowers, which smell like milk chocolate, top the 3′ tall clump nonstop from May until October. In the wild, Berlandiera pumila can be found from NC south to Texas, so its drought tolerance is excellent. We rate this as Zone 7a to 9b, but that’s only because we don’t have feedback from folks in colder zones yet. Please let us know is you have this survive temperatures lower than 0 degrees F without snow cover!
Gardeners interesting in attracting pollinators to the garden have no doubt experimented with one of the 20 native species of Pycnanthemum (mountain mint). While they are all lovely, most are too vigorously spreading to fit in a typical home garden. Enter Pycnanthemum flexuosum…the curvy mountain mint, is native from Virginia to Alabama, where it is found on moist to damp sites. This tightly clumping species is absolutely perfect for the garden, flowering now in July. This is our collection from Beaufort County, NC. We’ll be propagating this selection for a future PDN catalog. Hardiness is Zone 5-9a.
We always look forward to late June with the patches of Sinningia tubiflora burst into flower. This rhizomatous perennial, first cousin to African Violets’, is rock hardy to 0 degrees F. This South American native (Argentina, Uruguay, and Paraguay) forms a dense deciduous groundcover, topped with these long-tubbed, honeysuckle-fragranced flowers that attract nocturnal moths with a really long proboscis.
I’ve adored the perennial Lychnis coronaria (Rose Campion), since I first saw it in my grandmothers city courtyard 60 years ago, but the darn thing just produces far too many seed, which results in far too many seedlings. Imagine my joy at finding a sterile counterpart on my 2020 trip to the UK at the amazing nursery of plantsman Bob Brown.
Lychnis ‘Hill Grounds’ is actually a hybrid of Lychnis flos-jovis and Lychnis coronaria, discovered at the Hill Grounds garden of the UK’s Janet Cropley. In appearance, it’s a dead ringer for Lychnis coronaria with its lovely fuzzy silver rosettes and spikes of tacky fluroescent pink flowers, but without those pesky seed. We look forward to getting this propagated so we can share far and wide. Below are our 2 year old plants. Winter hardiness should be Zone 3-8.
Nierembergia ‘Starry Eyes’ is looking particularly dazzling in the rock garden at JLBG. Starting to flower for us in late April, this incredible gem is from our 2002 botanical expedition to Argentina. I distinctly remember walking by as our friends from Yucca Do Nursery extracted a small piece of this nierembergia with only a single flower attached. I remember thinking to myself how poorly nierembergias, in particular Nierembergia repens perform in our climate and how I wouldn’t have wasted my time on such a plant. Two decades later, boy was I wrong!
In our climate, Nierembergia gracillis ‘Starry Eyes’ blooms continually through the summer months. It thrives in full sun and a well drained, gravelly soil. Thank you Yucca Do, for all the great introductions!
The crevice garden has “woke” for spring, with early flowering plants in full gear. Here’s a shot of one small section, featuring Delospema dyeri and Iberis simplex (taurica). We hope you can visit in person for the second weekend of our spring open house, May 6 – 8, 2022.
Iris ‘Gerald Darby’ is one of those iris that doesn’t even need to flower to be garden worthy. Here it is in our garden this week, emerging with its’ purple leggings. This gem is a North American native hybrid of Iris versicolor and Iris virginica, known as Iris x robusta. This introduction of Iris breeder Gerald Darby was actually named for him after his death by another iris breeder R.H. Coe of England. Iris x robusta ‘Gerald Darby’ is equally at home growing in standing water as it is in typical garden soil. Hardiness is Zone 4a-9b.
Flowering now in the rock garden is the European native, Anthyllis coccinea…aka: red kidney vetch. This small rock garden legume (Fabaceae) is still in its first full year in the ground, having been planted last June…so far, so good.
Antennaria solitaria, the solitary pussytoes is looking great in the garden this week. This amazing native groundcover hails from Ohio south to Alabama, where it can be found in open shade or part sun, but always in dry soils. Despite being native in acidic soils, our plants below are thriving in our alkaline crevice garden.
In our cold frames, some plants will occasionally flower out of season, and that’s the case this week when one of our Orostachys ‘Crazy Eddie’ plants decided to flower out of season…fall is it’s normal time. The offseason timing won’t adversely affect the plant, and it did give us an unexpected photo moment. Because of the form of the flower, orostachys gained the common name, dunce caps, named after the pointed caps that poorly performing students were forced to wear. Of course, you’re probably showing your age if you knew what dunce caps were.
We love intermingling plants, often planting more than one type in the same space, where their growth habits allow them to comfortably co-exist. Here is a three year-old planting where we used ‘Gold Queen’ Hyacinth among a patch of our North American native groundcover juniper, Juniperus horizontalis ‘Bar Harbor’. Despite what many folks seem to think, there are no laws that plants in the garden can’t touch each other, so how about some more hand-holding in the garden.
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.
The dwarf groundcover Sedum tetractinum ‘Little China’ is superb throughout the growing season, but we particularly love when cold weather arrives and the olive green foliage turns to bright red in the sun…what a superb winter show. Hardiness is Zone 4a-8b.
Here’s a photo we took right before our first big freeze of the year, with the purple-foliaged perennial, Tradescantia pallida and our Iris ensata gate, built by NC sculptor Jim Gallucci. Gardens are an amazing canvas on which to paint with both plants and structures.
Although we’re celebrating Thanksgiving, Geranium ‘Azure Rush’ is still flowering as though it was mid-spring.
We love the winter hardy spiderworts, and Tradescantia ‘Pale Puma’ is one of our favorites. This hybrid of two northern Mexican species, T. pallida x sillamontana forms a lovely compact deciduous groundcover. Here it is in the garden this week, colored nicely and awaiting the first frost, which will send it into dormancy. In colder climates, it makes a great hanging basket plant.