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 20°F
and A. havardiana to minus 30°F.
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 0°F 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