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Succulents

...Carry the Garden Gracefully Into Fall

By Sean Hogan

With the Northwest’s reputation for wetness comes skepticism that succulents can thrive here. Thankfully, the skeptics are wrong! Not only are there a great number of succulents native to rocky outcrops that endure long periods of summer drought, but many more that are well-suited for our gardens and for container culture.

Succulents have many mechanisms by which they can reduce moisture loss, so the real question is: Which ones are best for us and under what circumstances? A commonsense approach, one I partake of on occasion, is to look at where they come from.

Succulents native to Mediterranean climates are adapted to summer drought, thus receiving the vast majority of their moisture in winter time, and are often perky and growing during the cool seasons. These are possibly the best for containers or unwatered walls and rock gardens as they can be left for long periods of time and are quite happy.

Some locals include plants we might take for granted, some of our stonecrops, such as Sedum spathulifolium, native from southern California to British Columbia. S. spathulifolium ‘Carnea’, is gray blushed with purples especially in the winter.Many silvery-blue forms—one of which is Helen Payne’s introduction ‘Cape Blanco’, a selection from the central Oregon Coast. Both ‘Carnea’ and ‘Cape Blanco’ are of the subspecies pruinosum, a plant prevalent along the southern Oregon coast where the stem leaves are as big as the rosette leaves and often covered with a beautiful white powder.

Sedum oreganum is frequently used as a rooftop plant as it forms great mats of shiny green foliage with yellow spring flowers and, other than the occasional tidying, is one of the easiest to grow. Sedum divergens, from the high Cascades, is happy at lower elevations, with tidy rounded leaves forming a thick mat.

Native to Mexico and adaptable to both gardens and containers, Sedum palmeri forms three-inch rosettes of blue leaves on small shrubs looking like an echeveria crossed with a jade plant. Similar, but looking even more jade-like, are both S. confusum and S. dendroides, making handsome shrubs to up to two feet or more with glossy green leaves and yellow flowers in late spring and summer. Both are easy-peasy to grow.

Other western natives include the sedum relative Dudleya. Think of them as winter-rainfall echeverias. Though the echeverias barely make it into the Mohave Desert from their habitats in Mexico, the dudleyas range from Baja to the central Oregon coast. One of the best for gardens, Dudleya cymosa, occurs inland with great green rosettes often blushed pink and flowers ranging from yellow to orange to nearly red. Dudleya farinosa can be seen on the sea stacks from about Pistol River south and forms colonies or rosettes of powdery, whitish blue leaves up to eight inches. Because of its mild habitat, extra frost protection might be needed for this one.

Of course, the genus Lewisia is well known to Northwesterners through many species, the most common being Lewisia columbiana and L. cotyledon and their hybrids. Though quite happy with summer drought, I’ve found that giving them consistently damp soil is best, especially in coastal areas. They can be prone to fungal attacks in warm moist soil so are actually much tougher in the spring and perpetually cool soil of the coast and should be treated with more sensitivity inland where temperatures are high in summer, providing an open north face and withholding water when temperatures rise.

Even a couple of cacti occur in winter-rainfall areas. One that is encountered by picnickers, usually unpleasantly, in the San Juan islands, the Columbia Gorge, the Rogue Valley, and further east and north is Opuntia fragilis. Though easily shattered by mere touch, it can form wonderful mounds in dish gardens or in the ground and can take almost any amount of moisture if sited in full sun.

For those able to water a little in the driest months, the world is your succulent oyster as there are literally thousands of choices. A myriad of cacti are hardy in even our coldest zones east of the Cascades, requiring little but light and scant moisture. One of my favorites is Opuntia basilaris (commonly called the beavertail cactus). A selection we named ‘Peachy’, came from an old garden in Albuquerque, New Mexico and has purple-blue pads forming a dense patch to about three feet and, indeed, peachy pink flowers in May and June. Another easy example, O. humifusa, native to the east and southeast, has bright green nearly spineless pads forming a small-scale ground cover with cheery yellow flowers in late spring. It can even tolerate partial shade and can be used in containers where, in time, it will perform as a hanging plant.

From South America, several small cacti including the genus Maihuenia, have thrived in our gardens for decades. The easiest of the two species to find, M. poeppigii, I first encountered in the Lowry’s garden in Seattle in the 1980s forming a mat about four inches tall and over three feet across with white spines on little “heads” covered with shiny green leaves like grains of rice— all occasionally punctuated by two-inch lemon yellow flowers.

Hens and chicks—the sempervivums—hail from western Europe, and enjoy a splash of summer water. Available in endless colors and forms, they are quite collectible and make good fillers.

The echeverias, also called hens and chicks, have many forms, often with ruffled leaves, and colors ranging from dark purple through pinks and blues to—yes—green. And quite a few are garden worthy. Echeveria secunda, our collection from a high elevation in Mexico, has been in our garden for many years unfazed by recent cold winters.

Other plants from Mexico and the US southwest include the agaves, yuccas, and their relatives, with far too many worthy possibilities to mention them all here. But the easiest include Agave parryi, looking like a beautiful, two- to three-foot-tall artichoke, and A. harvardiana from the Davis Mountains of West Texas, one of the toughest of the large agaves (to four feet!), with classically pointed leaves. Agave parryi, especially its variety couseii, has been recorded hardy to minus 20F and A. havardiana to minus 30F. With good air circulation and some protection from excess winter moisture (especially in coastal areas), there should be dozens of century plants adaptable to our gardens.

Look also for the false aloe, or Hesperaloe, as well as Beschorneria and Nolina as plants with great garden potential and bold effect. Another group of increasing interest is the genus Puya, a group of terrestrial bromeliads from the Andes, with silver to green to nearly red colors and unworldly flowers from metallic greens to deep blues to Martha Stewart chartreuse. Some are armed with vicious spines. I have been making a major effort to find these plants at their highest elevations and fully expect many to be frost hardy into USDA zone 7 (I think that’s in Canada somewhere).

A couple South African succulents include, first, the genus Aloe, often looked a longingly while visiting gardens on the southern Oregon or California coasts. But a number are tougher than we might think. Aloe aristata, is a little guy to only about four or five inches with bumpy green leaves, a plant that—having once had the status of grocery store plant—is now more difficult to find.

Aloe striatula is increasing in popularity and is actually an upright shrub to four or five feet with rosettes of narrow green leaves and bright yellow Kniphofia-like yellow flowers in spring. Below the mid- to upper-teens plants freeze to the ground but will resprout.

The ice plant, our second group of South Africans, have taken center stage in the Rocky Mountain states but can be a bit trickier in our areas with long periods of winter muck. From my own collections, at least a couple of dozen have taken quite cold temperatures, meaning waaaay below 0F but do require good drainage.

One exception is Delosperma nubigenum, from the high Cape, that forms a dense shiny green mat with an abundance of yellow flowers and seems to grow just about anywhere. For a more tightly clumping form, try the genus Faucaria, the group often called Tiger Jaws, and other mesembs as so many that were thought tender are actually quite tough.

I haven’t really even touched on the many colorful succulents that are more tender but often just as easy, requiring only a quick whisk into a frost-free place during cold spells from November to February in our part of the world.

Often, like Grandma’s zonal geraniums in the Midwest, they can be kept dry in a sort of stasis, not growing or stretching while being kept inside.

Succulents are one of the best excuses to build a dry stacked-stone wall mortared with pumice-rich soil. Happily, our relative ease of acquiring pumice makes building a suitable habitat easy, whether in a wall or in the ground. Most succulents are very happy to grow simply in a layer of pumice or pumice mixed with sand where their roots can reach denser and richer soil but the crowns never become saturated.

With the recent great increase in popularity of all these plants, varieties should be available in great abundance—so it’s a good time to climb aboard the succulent train! NWGN




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