Tender <sigh> but perhaps the most spectacular variegated Agave. It makes a great container plant for LARGE containers. To 5′ x 5′, it grows a little slower in containers. Make sure it’s sturdy and well built too because this puppy has been known to grow so vigorously as to shatter its own home. Use well drained cactus mix and add a handful of all organic fertilizer. Move to a freeze free environment such as an unheated garage if temperatures threaten to drop below 20ºF. Otherwise move it to a dry place for winter- under a south facing eave is ideal. Move it back out in the open when rain dwindles. Light summer water will speed growth. Leaves on this form are blue on the edges with a dramatic pure white stripe down the center. Wow.
Plant Type: Succulents & Cacti
Succulents offer dramatic shape and architecture rarely seen in our gardens. Whether hardy specimens for rock gardens or as dramatic seasonal plants nothing can beat their exotic structure. We include yuccas and succulent perennials in this list. There are several tricks to growing some of the more dramatic cold hardy Agaves in our climate. First, they should be planted as soon as the soil warms in spring. Tilt the rosette- this is best on a slope so that winter rain/ice will run out of the rosette and not gather and freeze- causing stress. Give them VERY good air circulation and take away any leaves from deciduous plants that have gathered in the rosette. Be careful. Some people use a blower, I’ve had luck with a can of air to clean office equipment. Save your hands from the spikes. Ouch.
Amend the soil for success
Normally we aren’t big fans of soil amending. It seems ridiculous for most native plants and its a huge carbon footprint when a truck has to bring you compost. In the case of cold hardy succulents amending is crucial in our climate because of our winter rainfall pattern. To site: Find a slope in full sun and excavate a large amount of the soil and save. Add medium to large boulders underground and on top. Incorporate 1/2″ minus or any other rough hued gravel into the saved soil and add a small amount of all purpose fertilizer and replace. Plant carefully, its not usual to see people using BAR B Q tongs and ovenmits to handle Cacti and Agaves. Plant hardy rosette forming plants at a tilt to avoid the accumulation of water/ice into the crown- it should be able to drain away. Plant, water in well. Most succulents grow when its warm so to establish them you should water them well in the first HOT summer they are in the ground. Roots will penetrate deeper as the soil temperature will be warm too. Let the soil dry completely between watering. For hardy Cacti and Succulents weeds and weed seeds can pose a difficult problem. Eliminating them is painful and tedious at any time of the year. Mulch with gravel and keep up on your weeding, especially in winter when you think least to do it.
Do not leave rocks/leaves in the rosette- it will cause winter rot
Remove all rocks and leaves from the center of the Agave before winter hits. The most efficient way is to use a blower and clean out the duff completely. If leaves are left in the crown they will rot the plant as they decompose. Agaves like to dry off between rainstorms. Put them in a fully exposed site facing south and do not let other plants over top them. This is also fatal. When desperate one of those cans of air to clean office equipment is also useful. Hold it no closer than 1′ from the plant (too close and it can freeze the plant as it is super cooled and can form ice) but at least a foot away you’ll still get enough of an air blast to knock just about anything out.
Winter aridity is the key to hardiness
If you plan on growing your hardy succulents in containers make sure that you don’t pot it into a container that is too difficult to move. Many succulents are very hardy to cold as long as they are dry in the winter. Most come from summer rainfall areas. They prefer moisture when its hot but dryness when its cold. Move containerized plant to a dry spot- under an eave or a cold greenhouse BEFORE winter rains begin and leaves start to fall. Dryness in winter can afford you almost 10ºF extra` degrees of cold hardiness. Keep them dry in winter. In the ground, this is where sharp drainage and amending pays dividends. Also, Agaves and hardy Cacti are actually tender until they have fully rooted out into the ground. The more roots you have, the better established the better the plant can resist cold and wet. Plant them as soon as it warms in spring and care for them for their first season. Again always let hem dry between irrigation. In subsequent years you can add one handful of all purpose prilled fertilizer each spring.
Location is everything
These plants all need to be sited carefully to succeed. Plant them in hot south facing aspects, on slopes, in hot rock gardens at the base of a hot wall. Even a thoughtfully placed boulder can absorb and radiate enough sun heat that it will offer benefits to these plants. Remember most of these plants are experimental in our climate. Our rainfall patterns that combine cold and wet are anathema to where they grow. Though they take preparation and thought very few plans offer as much bold structure and simplicity. They are worth it.
Climate Adapted Plants for Gardeners in the PNW
Agave bracteosa
Far and away the easiest Agave to cultivate in our climate and the handsome contorted sage green leaves are free of a deadly spike at the tip. Don’t be fooled, though. The leaves are lined in fine serrations that can cause a cut if you rub your person against them. To 3′ tall and as wide for very well-drained soils in full sun to very light shade. Amend the soil with pumice to sharpen drainage if needed. Ideally adapted to slopes. Good dimensions as a large focal point in a rock garden or clustered into clumps in the gravel bed. Accepts the highest reflected heat. Light summer water speeds growth. Often produces offspring from the base. These can be detached and replanted when its truly warm. Bold mature clumps are breathtaking. Wonderful life in hellstrips. Obviously deer resistant, but the tips can be brittle so handle them with care when planting. Excellent year round appearance and texture.
Agave harvardiana
Spikes! A very upright and pokey Agave with steel blue/gray foliage that forms large rosettes. To 3′ across eventually this cold hardy Agave demands excellent drainage but is worth the effort. VERY well drained soil- amend with liberal amounts of pumice and gravel. Excellent on a slope. Plant with the rosette tilted to shed winter water. Makes new pups happily and they will often come up quite a distance from the parent plant. To 3′ tall when up and established. Great in containers that you protect from winter wet. Move to a covered place in fall- a south facing eave is sufficient. Cold hardy below 0ºF- when established. Best to plant in March or April so that it has the longest possible season to develop a root system going into its first winter. Light summer water to none. High deer resistance.
Agave ovatifolia ‘Frosty Blue’
A real winner in our climate this is perhaps among the easiest bold Agaves to cultivate. Large rosettes of flared deadly leaves are a luminous light blue. The whole rosette can achieve 3′ wide and nearly as tall but smaller is more common. Excellent tolerance of the combination of cold and wet that Agaves mostly despise. This plant also is less prone to injury from necrosis of damage- slugs, snails etc. Full sun to a surprising amount of shade, though you’ll want to avoid the overhead detritus of trees into the rosette. In full sun such as a bare parking strip it revels in heat, exposure and fast drainage. Amend the soil to at least 1/2 pumice and 1/2 virgin native soil. Water to establish then only what falls from the sky. Obviously site away from paths- stab wounds suck, literally. In Mexico they planted large agaves in front of the bedroom windows of their female children. The idea I guess was to deter suitors with bad intentions. But its a neat story and you could see how it would work. Obvious awesome deer resistance. Sometimes called Whale Tongue Agave.
Agave parryi ‘Flagstaff’
From the very far north end of this variable species range in Northern Arizona near—‘Flagstaff’. High elevation form that is found above 7000′ in the wild. Very cold hardy moderately large Agave. Full sun and very well drained soil. You must amend the soil with pumice and gravel to avoid wet accumulating around the crown in winter. This is made all the more easy by placing on a slope. The rosettes should be tilted to shed winter wet. Very stiff and sharply tipped steel blue leaves form a rosette that is at first upright then spreads out a little. Remove leaves from deciduous plants that collect in the rosette in autumn- they blow in from god knows where and leaving them can encourage rot. Excellent in containers. Move containerized plants under an eave or overhang to keep it dry in winter. No water required after initial establishment. Beautiful form of this cold hardy species. High deer resistance.
Agave parryi ssp. couesii
A really pretty pale blue Agave with sharp angular leaves in a remarkably symmetrical rosette with age. Cold hardy and it requires very well drained soil in a hot position. A south facing slope is ideal in soil that has been amended with liberal amounts of pumice and gravel. And you should tilt the rosette so that water does not collect in winter. This variety is a little slower than others. Aside from perfect drainage it requires a little bit of heat and patience. To 20″ tall by 30″ wide in time. Great container subject- make sure the container is sturdy and large enough to accommodate both a spreading primary rosette and prolific pups which crowd the base. In time it can form bold colonies. Move containerized plants to a dry location in winter. Remove deciduous tree leaves that collect in the rosette in autumn to stave off rot. SW U.S. High deer resistance.
Agave parryi ssp. neomexicana
New Mexico Agave is a spike wonder. Much more upright-growing than the species with sharp-tipped leaves that terminate in a blood red thorn. OW. Forms a very symmetrical plant with many leaves of steel blue. Full sun and VERY WELL-DRAINED soil. Excellent on hot slopes where it will tilt the rosette to avoid winter wet. Pups, heh, freely and you will soon have many rosettes. Amend the soil with pumice and gravel. Make sure there is plenty of air in the soil and no place where water could collect. Fantastic specimen plant for a dry garden/gravel garden. Water through the first summer to establish then none in subsequent years. Clean out the rosette when deciduous leaves collect in there- a shop vac works great. The leaves will cause rot when they decompose….so they must go. Great in containers- large, sturdy containers. Cold hardy. High deer resistance.
Agave parryi ssp. truncata
Consistently one of the most successful Agaves for gardens in our region. Soft gray rosettes have leaves with a distinct upright habit. At the tips of the wide leaves is a single (deadly) black thorn. Very nice. Full sun and very well drained soil with little to no summer water when established. This Agave requires soil that is never soggy- amend heavily with pumice and gravel to create air pockets. Plant this (and all) hardy Agaves in our climate on a tilt. The tilted rosette sheds rainwater and it keeps it much drier in winter. Ideally, this Agave should be sited on a hot, south facing slope. In autumn deciduous leaves from (everywhere) seem to blow into the rosette and collect. You must remove these immediately so that they do not rot the center of the plant. A shop vac works wonders…so do bar-B-Q tongs. Excellent in containers. Its best to plant hardy Agaves in early spring to early summer. They require a long season to develop a root system which ensures that they are cold hardy. No root system and not so hardy. Hardy below 0ºF when dry. Highly deer resistant.
Aloiampelos (Aloe) striatula
We’ve grown a lot of Aloes with purported cold and wet hardiness and this is the one that has been the most successful. A large succulent shrubby plant with rosettes of deep green succulent foliage. In late summer to autumn a showy display of large yellow flower spikes can occur. Very pretty and loved by all nectar seeking folks. Give this South African perennial VERY GOOD DRAINAGE in full sun and a warm position. A slope is always helpful. Amend the soil with plenty of gravel and sand as well as compost- these guys do need to eat- so a little handful of organic fertilizer is recommended. Capable of freezing to the ground (below 15ºF) and resprouting from the base when truly warm weather arrives. Plant on a south or west facing slope preferably against a warm wall or boulder for added reflected heat. Easy, if large, container plant that you should protect from temperatures in the teens. To 3′ x 3′ on average in our climate. Mostly evergreen here. Combine with Agave, Cactus which will also increase their growth rate if you provide light, consistent water during hot weather.
Cylindropuntia whipplei ‘White Spine’
Love this small growing Cholla that has the most amazing luminescent white spines. Densely branching low plant to 2′ tall by 3′ wide in time. Not terribly fast growing. Fast draining soils that have been amended heavily with gravel and pumice and ideally on a slope will make this a focal point in the dry garden. Light summer water will speed growth. Extremely cold hardy and not terribly fussy. Give it an open position with sun all day long. Wonderful in rock gardens. Flowers we have not seen but we assume with this species that they will be pink/purple in summer. Highly deer resistant. Great container plant. Move to a dry position in winter just for extra protection from wet.
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