ANYONE WHO HAS ever had to prepare a talk knows the angst of editing pictures. All of the plants in my garden are my favorites. The ones that turn out not to be my favorites go to plant sales or to a neighbor who puts them in heavily watered, super-rich soil and then assumes they were annuals when they don’t reappear the following spring. The plant pictures on the cutting-room floor are all loved for various reasons and it’s really hard to leave any of them behind when you feel they are equally deserving. In this article for the Rock Garden Quarterly, it seemed the perfect time to talk about some of the plants that didn’t make the cut through no fault of their own.
There is never time to talk about the garden that is being made at the bottom of our property next to the road. What had originally been a small stream was turned into a pond by the former owner. It was basically a 14-foot-deep (4.26 m) hole that covered one-third of an acre (1300 m2), and home to very large turtles, water snakes, and muskrats. The land across from us was sold to build McMansions and the developer needed our permission for drainage. The quid pro quo was filling the pond and turning it back into a stream. For the first time, I had an area that was wet year-round with a small stream and springs and with room for all sizes of plants. It is also the one place where there is no rock. A sloped, shaded area was filled with rodgersias, Ranunculus aconitifolius, Darmera peltata, Aesculus parviflora, hellebores, cimicifugas, astilbes, and primulas. On either side of the stream are Primula japonica, camassias, Iris ensata, Iris sibirica, Trollius europaeus, daylilies, and a double-flowered Caltha palustris. It was a surprise to learn that many “shade” plants are perfectly happy in full sun when their feet are constantly moist. Ligularias were unfortunately too successful and were dug up and moved in front of the 8-foot (2.4 m) fence that was added after several years of planting and having the “antlered rats” eat everything. Now I have both moisture and no deer damage, any Northeastern gardener’s dream.
Above the front cliff, Eranthis hyemalis starts the season in early March. It blooms as the last of the snow is melting. I learned to dig up a patch in bloom and move it to increase the size of the planting. Now it cuts a wide swath in the light shade of an old lilac tree and will be followed by galanthus, epimediums and American ginger (Asarum canadense) that have just been allowed to spread. It’s a no-upkeep planting that increases in size.
Early in April, the incredibly dissected, fleshy foliage of Lomatium grayi appears. From seed, the foliage exhibits variation, always very dissected but some are a really fine filigree. A member of the Apiaceae, it is known as “biscuit root” and “Gray’s desert parsley.” The bright yellow flowers are held in flat umbels above leafless stems and the large flat seeds turn chocolate brown when ripe, which is another decorative element. It goes dormant in summer. The plant makes many seedlings right around the mother plant which immediately develop a thick, strong taproot, making moving even small seedlings difficult. The young stems and roots were a staple for the Paiute Indians of the American West. The older root is also edible but not very tasty and was called starvation root. This is a western plant of open, dry rocky places with an average annual rainfall of 10 to 20 inches (25-50 cm). Despite this, it has done very well in my garden.
Another April- blooming plant is Paeonia tenuifolia, the fern-leaf peony. If it never flowered you would still love it for the delicate-looking, very finely divided foliage, but the flowers make this a must-have plant. Mine has single, deep- red flowers which will last a week unless there is a hard rain. You plant it where you want it and then just let it grow. Here it doesn’t seem to mind strong sun, drought, and wind. The plant is late-summer dormant. It can be divided, but I’ve never had the nerve to do it. Sometime after it has finished blooming the flowers of Paeonia peregrina will start. These are also red, and the petals surrounding the boss of gold stamens are so shiny they almost look plastic. The foliage is deep green and more typical for a peony. Supposedly it must be protected from wind, sun, and drought, but that is its typical diet here and it grows and flowers very well anyway. Both of these peonies are very desirable in the garden and bloom before the usual border peonies.
Glaucidium palmatum ‘Album’ is a gorgeous shade plant which was a gift originally from Harold Epstein’s beautiful woodland garden in Larchmont, New York. The large leaves are a fresh green and the stunning white flowers are huge. It seems to be able to go dormant towards late summer if the drought is very bad and come back again in the spring. In this garden that’s a huge plus. Harold was incredibly generous, always bringing gorgeous woodland plants to my sunny, windy garden on his visits. These included Trillium grandiflorum and Sanguinaria canadensis (both with double flowers), and Iris gracilipes. Harold and his wife Esta and I would walk around the garden and he would choose a spot to try his latest gift. Many of the original plants he brought are still going strong. I lived in dread that he would notice if I had killed one of his plants, but if he did, he never said anything.
When you are the owner of a very dry garden, you can entertain certain plants which might come under the classification of “garden thugs.” Several of them are planted and enjoyed here without the usual ill effects, but my favorite is probably Ranunculus ficaria and its many hybrids. One of the most decorative is Ranunculus ficaria ‘Flore Pleno’, an early spring bloomer. This one has made a lovely mound a few inches high of dark green leaves with double yellow flowers. It is an excellent form that stays tight and is very well behaved. Another of the so-called thugs is Asarina procumbens ‘Nana’ The foliage is soft and gray-green, the flowers are large and pale yellow – if it didn’t have such “taking” ways, it would be high on any gardener’s list of desirables. It is not truly hardy here but maintains itself with self-sowing. Often, I will twitch out a tiny seedling and literally paste it into a hairline crevice on the cliff. Enough will take to make a nice display on what appears to be a solid wall of rock. It seems to be able to grow anywhere, happy here in shade and also in sun.
My garden is not a place where you will find the Kabschia saxifrages with their gorgeous flowers or the many blues and purples of mounds and cascades of campanulas. Two enemies of these beautiful plants are always here in abundance: summer heat and drought. To that add humidity for during the worst of the summer we have the really dreadful combination of heat and humidity accompanied with long periods of drought. The silver saxifrages will do reasonably well here and are well loved, but theirs are not the brilliantly colored flowers that rock the garden. The mossy saxifrages are also a failure here with one exception – Saxifraga cebennensis. This was a plant given to me many years ago by Ellie Spingarn, a wonderful rock gardener and plantswoman who gardened in Redding, Connecticut. Like anyone who has gardened for a long time, my rock garden is also a friendship garden. The daily working tours are accompanied by remembrances of the people who gave me plants to try and who encouraged all my garden building projects. Although Saxifraga cebennensis (one of the “mossies”) is not supposed to tolerate drought or much sun and is recommended for alpine house culture, it has flourished here for many years. It is planted in a trough next to a piece of tufa, which seemed a reasonable thing to do since it inhabits limestone areas of the Cévennes Mountains of France. The trough was placed north of the house, receiving shade by mid-afternoon from a large tree. It did very well despite long periods of summer drought, because a few hanging plants were in the area and those did get watered sometimes. Any fallout spray would reach the trough and keep its occupants happy. Saxifraga cebennensis for ms a low mound with large, brilliant white flowers that make a lovely display. Years later, the tree was wiped out by a tornado and we replaced it with a lath shelter because the dog pen was now in strong sun. I still have the original plant which waxes and wanes according to weather conditions, but to be on the safe side I’m trying to grow it from seed, the preferred method of propagation.
A perfect understory plant for hellebores and epimediums is Thalictrum kiusianum, a dwarf meadow rue from Japan and Korea. The foliage emerges here in late spring after most of the hellebores have finished blooming. It takes a while to settle in but then starts to spread slowly. The soft, delicate foliage is followed by airy clouds of tiny, lavender, dainty starry flowers. No more than 6 inches (15 cm) high, it has seeded itself here but not enough, because you can’t have too much of this charming plant. It seems indifferent to pH, and accepts quite a bit of sun although it has spread more in the shadier areas. It can be divided when the new growth appears in spring.
Many years ago, I was lucky enough to see Aquilegia scopulorum in Red Canyon in southern Utah, where it grew on a very steep, sliding scree. The population was not concentrated but appeared here and there as far up as I could see. The plants were quite variable both in size and flower color. They ranged from a scant few inches (7 cm) to a foot (30 cm) high with pale to dark blues, soft lavenders to purples, and lovely bi-colors, many of which would have taken pride of place in any rock garden. No matter the size of the plant, the flowers were large and immediately identifiable by their ridiculously long spurs. It was a very dry area, but they will grow and stay here for a number of years, probably best planted in a trough and far away from any other aquilegias, because the genus as a whole has some of the garden’s most promiscuous plants.
Astragalus loanus is a rare endemic of Sevier County, Utah, which seems to be the home of a number of really great plants. This treasure is quite small with a number of silky-haired paired leaves surrounding the caudex. The large flowers sit straight up around the plant and are white with purple tipped keels. It’s found on slopes of volcanic gravel and needs sun and excellent drainage in the garden. The seed pods are large with silver hairs. It actually made several pods in the garden, but some critter ate them before they were ripe enough for harvesting. Even in the wild, collecting astragalus seed pods can be very frustrating because when you open them up to harvest the seed you often find that tiny bugs have gotten there before you and have damaged a lot of the seed.
Penstemon debilis grows in western Colorado with only a few known locations in Garfield County. It’s also called the parachute penstemon due to its proximity to Parachute, Colorado. It grows on very steep, south facing, unstable oil shale slopes, at elevations from 5,500 to 9,100 feet (1600 - 2700 m). It is a xeric plant with succulent, glabrous leaves that are a pale, almost blue, green. The flowers in the one I grow are large, funnel-shaped, and the palest of pinks. Penstemon debilis is soboliferous, which means as the unstable slope on which it grows moves inexorably downward and the leaves start to get buried, the stems are able to elongate and the plant is able to unbury itself. A mature specimen could have the roots anchored quite some distance above the plant. The plant was discovered in 1986 and is currently listed as threatened. I grew this years ago from Alan Bradshaw’s Alplains seed company (collected when it was okay to do so), and from the resulting seedlings only one survives, but it has been in the garden for quite a few years. Each spring there’s a celebration when the plant reappears because there may never be a chance to grow this one again and it is really lovely and very different. Alan described the habitat from which he collected the seed and it sounded like a “near-death” experience. It was growing in a steep, shifting scree below cliffs, with the scree sliding towards a sheer drop. He described the plants as rambling through
the scree. In my garden conditions (very lean scree), it has grown as a low mound. It makes you appreciate seed collectors and understand why some seeds are expensive. The only caveat here had been that the foliage, which is so beautiful, can be disfigured by too much rain. The same could be said for lewisias, but it certainly hasn’t stopped me from growing them. In all the years this plant has been in my garden I’ve never been successful at harvesting seeds nor has it self-sown.
Erigeron scopulinus is the smallest erigeron of my acquaintance, but definitely one of my favorites. It makes a closely-knit mat of small linear leaves of a bright dark green, a wonderful foil for the brilliant white daisies that are almost stemless. A dainty looking plant from Arizona and New Mexico where it grows on ledges and cliff crevices, it’s actually very hardy and seems to be as tough as nails. It is drought tolerant but not xeric, although it managed to survive last summer’s horrific drought. If you want to plant it in a trough make sure it’s a big one because it will spread, especially when it is well watered. I’ve always been tempted to try under planting it with small bulbs.
Sedum cauticola ‘Lidakense’ blooms at the end of the summer and into the fall when there is not much color in the rock garden. This
variety has dark red-pink flowers, contrasting beautifully with the silver-blue fleshy leaves. This is not a sedum you will regret planting because it seeds itself sparingly, just enough for you to dig out the occasional seedling and plant it in another part of the garden that needs some fall color. I grow it here on top of a wall and it managed somehow to seed itself in the wall itself. It’s very easy to grow, but considering the “taking ways” that too many sedums have, it might be good idea to grow it lean.
In the Dolomites in Italy, Globularia cordifolia is found above tree line growing in limestone rubble. Globularia cordifolia subsp. nana is one of the mainstays in my garden. It is a smaller plant but still distinct from Globularia repens which is even smaller. It makes an ever increasing adpressed mat which has the ability to flow over obstacles (such as rock) that might be in its path. It gets woody with age but is still covered with the small dark green leaves and continues to flower well. The flowers range from the pale blue of this form to the dark blue of Globularia trichosantha, which is a larger plant in all respects.
Lilium bulbiferum var. croceum is one of the glories of the Dolomites when in bloom. A brilliant orange showstopper in its habitat of mountain meadows and hillsides, at its full height of 3 to 4 feet (about 1 m) it stands above most of its neighbors and telegraphs its presence from some distance. The large, wide open, unscented up-facing flowers have an interior flare of paler yellow-orange dotted with dark chocolate spots. The Latin for “bearing bulbs” is “bulbiferum,” and the plant has tiny aerial bulbs along the stems. It prefers sun and alkaline soils but will grow well in lightly acidic soils. It also wants consistent moisture, which it doesn’t get here, but that simply means the growth is slower and the plants a bit lower at 2 feet (0.6 m). It is generally considered to be a fast grower.
Saponaria x olivana has been in my garden since 1980. I think of it as the “tonsured monk” of the garden because it starts blooming on the outside ring of the tightly leafed low mound and stays that way for some time before the flowers begin opening towards the center and it becomes a solid mass of color. The flowers are really luscious, a soft pink and very large (Saponaria x olivana ‘Bressingham’ is a darker pink and lovely in bloom, but the flowers are tiny in comparison). In all the years I’ve grown this plant it has never produced a seedling. It grows from a strong central taproot and unfortunately no part of my plant has ever layered itself (called the lazy man’s propagation trick, which works very well with some penstemons).
If the pretty little annual blue bachelor’s buttons are the only thing that comes to your mind when centaurea is mentioned, you are missing a wealth of lovely and interesting plants for the rock garden. Centaurea pindicola from Mt. Olympus in Greece is one of the stars of this large genus. Known also as the Pindus star thistle, the plant has rosettes of large, deeply lobed grey-green leaves that have long silver hairs. The white thistle flower is huge with very narrow petals divided in three at the end and sits right on the rosette. Towards the center
of the flower there are some scattered black petals, which I’ve heard described as looking like long eyelashes. This may be a bit fanciful, but the contrast is quite wonderful. This has been growing peacefully in a sunny scree for some years and just recently I learned that it was fairly rare and not found in many gardens. My original plant came from Maria Galletti, the owner of the former Alpines Mont Echo Nursery in Canada. Another very nice one for a limestone scree is Centaurea chrysantha. It has golden thistle flowers sitting on a rosette of leaves so felted with silver hairs that the rosette appears to be white. When the flowers finish you see the long chocolate spines on the calyx which are very decorative (and very sharp). Although they have not been registered as lethal weapons, wise gardeners will approach only with very tough gloves.
All of the rock garden convolvulus are really beautiful, floriferous plants, usually flowering in brilliant whites starting in June. Convolvulus suendermannii, which is supposed to be hardy to Zone 2, has large, clear pink flowers and it flowers on and off all season. After flowering it seems to take a brief rest and then buds start to form again. This summer this happened also with Convolvulus compactus for the first time. The leaves are also very beautiful – long and narrow, with distinct veins, and a lovely silvery-gray thanks to the densely covering silver hairs. It is a wonderful plant for full sun and a deep, lean scree to accommodate the taproot. In nature this convolvulus species, so cherished by rock gardeners, becomes very woody with age, the tap root extending and looking almost like a small trunk.
All of the plants discussed have one thing in common—their value in the garden. The value varies: it could be beauty, color, size, ease of culture, longevity, dependability, or length of bloom time. That they all were on the cutting room floor is due to time constraints and nothing else. There are still many plants left not mentioned but I’ll have the pleasure of praising a few more of them in the next issue.