This Agave is one of the most under-rated for gardeners, in my opinion. Its rather wide, small-toothed leaves go from pale silvery-white in winter to green with pinkish margins in the summer. The rosettes are often solitary, but may form a few offsets. It is very easy to grow and tolerates moisture better than many Agaves. This collection is from 6,600' in the Pinal Mountains near Globe, which is probably about as high as it grows. I will not soon forget the incredible view of canyonlands and rolling open forest from this spot! How large will these plants get? The plants from which I collected had rosettes about 4' wide. However as I drove down the south side of the mountain, plants had increasingly large rosettes, to as wide as 7'! Are the rosettes smaller because they are higher up and more exposed, or is there some genetic difference? I wouldn't be at all surprised to see plants from this collection grow 6 or 7' wide or more in a sheltered spot, with some summer water. These plants should be hardy to at least 0°F, maybe lower once they get some size.

Discovered only a few years ago high in Mexico's Sierra Madre Oriental, this fabulous large Agave is still just making its way into cultivation and remains rare. The large, toothy green leaves create white impressions in the surrounding leaves as they expand. Over time it can be expected to make a large globe to perhaps 5' wide of rather compact habit. In the wild, it grows in open pine forests as high as 10,000', where it is subjected to heavy frosts and snow. Thus, it is excellently suited to the climate of western Washington, provided drainage is adequate, and it can even tolerate partial shade. In eastern Washington, it easily survives 0°F but is very unhappy about hot, dry summers without irrigation. If all that weren't enough, it is the only Agave native to Montana! Everyone in Wyoming is so jealous. Not really.

One of the best known hardy Agaves, this species needs little introduction. It is one of the most attractive species, forming tight rosettes of numerous blue grey to silvery, stout leaves tipped with black spines. It is very tough and tolerant of rain and cold, and has grown to maturity and flowered in the Pacific Northwest. This exceptional form growing at 7,050' at a mountain pass in New Mexico (not actually Emory Pass, which is higher, but another pass west of there, east of Mimbres), has been collected and offered frequently by many nurseries over the years - and deservedly so, as it is still one of the best forms of this species, growing to the exceptional size of 4' across, with very large leaves. Also, it comes from a high, cold, and snowy area, and should be hardy to at least -20°F.

Wow! This behemoth of an Agave is truly one of the most impressive garden plants one can grow. Its monster rosette of grey green leaves with hefty spines produces occasional offsets. Ultimately reaching dimensions of 12' wide or more, it needs a large space and should be surrounded by plants of similar scale not to be an overwhelming figure in the cactus garden. Hardiness reports vary anywhere from about 5°F on up to 20°F - this may owe to differences in provenance or to the possibility that many plants considered to be this species are actually a form of A. protamericana, which is much hardier. But if you don't want to risk it, it's still an impressive container specimen, and produces plenty of offsets which can be saved as insurance against a cold winter.

While it's not quite hardy in the Northwest, this tree Aloe deserves recognition for its beauty and ease of growth. The succulent, pale blue-green leaves are arranged in one plane, and as the plants age they produce impressive spikes of showy red flowers held well above the foliage. After many years it may branch and achieve a tree-like stature but it is quite slow. It will appreciate full sun and good drainage; provided these conditions, it doesn't seem to care if it is watered heavily or barely at all. A native of the Cape Region of South Africa, it is adapted to a pattern of winter rainfall and dry summers: as such, it has considerable resistance to rotting off at the base over winter, as certain succulents are known to do. In our greenhouses we subjected them to winter wet and frost to 26°F and they still look just fine. (By contrast, Aloe dichotoma and such, being from much warmer climates, are considerably fussier.) Its slow growth makes it perfect as a very undemanding long-term potted specimen.

Of all the Aloes touted as cold-hardy, this is the one that actually is, and will give you little trouble about winter moisture or drainage or any of those other bothersome trivialities that frequently afflict hardy succulents. Rising to 4 - 5' and spreading wider over time (if it's really happy), stems of succulent, true-Aloe leaves are eventually topped with very showy red and yellow flower spikes. It prefers full sun with some summer water and freedom from competition from other plants, and not-too-heavy soil. In a normal Seattle or Portland garden, it does very well, though it requires irrigation to grow quickly without irrigation. This plant is truly a must have for any subtropical, Mediterranean or desert-themed garden (and I'm not just saying that to try to sell it (although I would, admittedly, but in this case, I'm not)). Now as to the specifics of winter performance: in the Pacific Northwest it remains evergreen above about 20 - 22°F. Below this temperature it freezes to the ground, but it will come back in mid to late spring if well established, and it should be watered and fed heavily after freezing back to ensure it will bulk up again. I would call it root-hardy to the 0 - 10°F range. In hotter climates, it may prove hardier than this.

This soft-leaved Agave and Yucca relative from Mexico lacks spines, but it is still (dare we say?) wicked awesome. The soft green leaves form an open rosette to 3 - 4' across. In summer it produces tall flower spikes on a bright red stalk that may reach 6'! Although basically evergreen, it may freeze to the ground in a cold winter in the Northwest, but then it also dies back and resprouts from the base with multiple new rosettes after flowering. For this reason it doesn't mind being watered and fertilized heavily in the summer to bulk up its size before the following winter. It is not as xeric as Agaves or Yuccas and it can handle average garden soil (and doesn't mind well-amended soil) and partial shade. In fact, it may suffer without some water if planted in full hot sun. Leaf damage may occur around 15 - 20°F in the Northwest (at a lower temperature in hot climates) but it is ultimately hardy to somewhere in the 0 - 10°F range once well established.

This slow-growing succulent makes a tight cushion of fleshy green leaves to only an inch or so high. In spring it produces a stunning show of bright yellow flowers that cover the plant! Not a fast spreader like D. cooperi, it remains compact: perfect for setting between stones, in a trough, or in a container with other succulents. Mass planting would be a fun idea too. It is easy to grow in sun and totally hardy, but needs good drainage, especially in wetter gardens. Summer water will give it a boost in hotter gardens.

Could it be? A hardy Echeveria? Perhaps not quite, but this species is about as close as one can get. It was collected near the top of a really high (like, 10,000') mountain in Mexico and is expected to handle temperatures down to about 15°F - perhaps lower? We don't know yet. In appearance it is rather similar to many of the tender Echeverias, forming tight clumps of glaucous, silvery rosettes, and producing generous quantities of yellow flowers on pink stalks in late spring. We are not certain of the precise details of where this was originally collected, but when I get a chance I'll have to ask the folks at Cistus Nursery who were kind enough to share this with me.

In the summer of 2005 I heard tales of a huge, yuccoid plant with enormous strap-like leaves and a stout trunk growing in front of a north Seattle city light substation. This plant turned out to be a thriving Furcraea, a genus of magnificent plants not typically associated with climates colder than California. So began my search for a cold-hardy Furcraea, which seemed like it was going well until winters started getting colder again and the Seattle plant (we admit) froze. Anyway, we still feel like offering this as one of the hardiest Furcraeas and a fun plant to grow since they are just so fast, and cool. These are the same plant that has been known as F. longaeva in California, and F. bedinghausii is probably another synonym or at least a very similar plant. The trunk may grow anywhere from 2 - 15' (about 6 - 10' is usual) before producing an amazing flower stalk 30-40' high! White flowers are followed by hundreds, sometimes thousands of small bulbils that can be used to start new plants. At this point, the plant dies, but then you can start over with thousands more little baby plants! Furcraea parmentieri tolerates drought and heat, but it thrives quite well on moisture and in cool weather. It will look great in a container for a long time if you're too chicken to plant it out. This selection from a plant that flowered in Bournemouth, England, and is hardy to around 18 - 22°F, perhaps lower for brief periods, once established.

In the summer of 2005 I heard tales of a huge, yuccoid plant with enormous strap-like leaves and a stout trunk growing in front of a north Seattle city light substation. This plant turned out to be a thriving Furcraea, a genus of magnificent plants not typically associated with climates colder than California. So began my search for a cold-hardy Furcraea, which seemed like it was going well until winters started getting colder again and the Seattle plant (we admit) froze. Anyway, we still feel like offering this as one of the hardiest Furcraeas and a fun plant to grow since they are just so fast, and cool. These are the same plant that has been known as F. longaeva in California, and F. bedinghausii is probably another synonym or at least a very similar plant. The trunk may grow anywhere from 2 - 15' (about 6 - 10' is usual) before producing an amazing flower stalk 30-40' high! White flowers are followed by hundreds, sometimes thousands of small bulbils that can be used to start new plants. At this point, the plant dies, but then you can start over with thousands more little baby plants! Furcraea parmentieri tolerates drought and heat, but it thrives quite well on moisture and in cool weather. It will look great in a container for a long time if you're too chicken to plant it out. This collection is from a cultivated plant in a rather cold garden in Walnut Creek, California and is hardy in the neighborhood of 20 - 22°F, perhaps lower for brief periods.

Here's a plant we like to offer that actually isn't that rare - being one of those pass-along succulents that Grandma has kept going since the dawn of time. But that doesn't mean it isn't cool - what's not to like about chunky little glaucous leaves that assume a purplish cast in the sun? And it's extremely easy to grow, tolerating sun or shade, and moist or dry soil, as long as it isn't too soggy. The exciting part is that under the right conditions it can actually overwinter outdoors in the Pacific Northwest, though it can generally be expected to freeze to the ground more winters than not. To ensure success, provide it with excellent drainage, the protection of an overhead canopy, and some sort of mulch (one Portland area gardener I know of was quite successful growing it under a small pine). And of course it is a piece of cake to propagate from either stem or leaf cuttings, should you desire to save a piece for insurance. It's hard to give an exact hardiness rating, but anywhere that the ground doesn't freeze very much, or very deeply, it should overwinter successfully, like approximately in (dare we use this system just once) USDA zone 8 (7b?) and up.

Orostachys is an intriguing genus of succulent plants related to Sedum but far less commonly grown. I had been under the impression that they are challenging subjects best left to experienced rock gardeners, but this species certainly has not followed that rule: it has grown with remarkable ease and we haven't managed to kill one yet. It makes cute mid-green rosettes that hug the ground and send up surprisingly conspicuous spikes of white flowers in spring. As with Sedum, the best use of this plant is probably in a rockery, trough, or in a pot combined with other succulents. It is native to China, and seems content with half to full sun in the Northwest.

An exotic looking succulent with pale grey-green rosettes to 1.5" across, this looks like something that ought not to be hardy but it is. At least it is, as long as temperatures don't drop below about 10°F, and perhaps lower in dry climates. It's great for rockeries, containers, or any dry garden beds to fill in around your hardy cacti and succulents. Native to Mexico.

A Yucca even your madre would love. Closely related to Y. schottii, but originating in the spectacular mountains surrounding Barranca del Cobre National Park, Mexico, this species ire relatively new on the scene: until very recently, this Yucca has been nearly unavailable in US cultivation outside of a few botanic gardens in the Southwest. It will form a stout trunk with broader, strap-like leaves than most Yuccas, and is often found growing in the shade and in rather moist situations in the wild. Like Y. schottii, it seems very vigorous and usually bluer in cultivation than in the wild. Its hardiness is unknown but somewhere around 0 - 10°F seems probable - perhaps lower. Be among the first to try this rare Yucca in your garden!

"Mountain Yucca" is a species from relatively wet, mountainous areas of southeast Arizona, southwest New Mexico and adjacent northern Mexico, that deserves more attention. A tall and stately plant to 20' with a symmetrical crown of sharp-tipped leaves, it is still rare in cultivation but should be very adaptable, handling partial shade (though best in full sun), cold temperatures, and moisture. Although the leaves are usually blue-green in the wild, all plants I have seen in cultivation have blue leaves. It thrives in Seattle, and its symmetrical form and screaming blue color are unparalleled. It has recently been reclassified as Y. madrensis but I think I will stick with the name Y. schottii for now to avoid confusion. This collection from the Atascosa Mountains, Arizona, represents exceptionally robust plants with very long, bluish leaves. This form should be hardy to at least 0°F, perhaps lower. It’s hard to choose, but this is my favorite Yucca, and, with some summer water, probably the best really large Yucca for the Seattle area.

"Mountain Yucca" is a species from relatively wet, mountainous areas of southeast Arizona, southwest New Mexico and adjacent northern Mexico, that deserves more attention. A tall and stately plant to 20' with a symmetrical crown of sharp-tipped leaves, it is still rare in cultivation but should be very adaptable, handling partial shade (though best in full sun), cold temperatures, and moisture. Although the leaves are usually blue-green in the wild, all plants I have seen in cultivation have blue leaves. It thrives in Seattle, and its symmetrical form and screaming blue color are unparalleled. It has recently been reclassified as Y. madrensis but I think I will stick with the name Y. schottii for now to avoid confusion. In the Chiricahua Mountains of Arizona, Yucca schottii can be found at the amazing altitude of 8,200'! This collection from 7,950' (the highest point where we could find one with seeds) should tolerate temperatures to at least -10°F.