Ceroxylon is genus of about 20 species of feather palms from the Andes of South America. They are a very unique and intriguing group for several reasons. First of all, their size is remarkable; in fact, they are the tallest of all palms. C. quindiense has been known to grow as tall as 200'. When they were first seen by Europeans (prior to the discovery of the California redwoods), they were thought to be the world's tallest trees. Secondly, they grow at a higher elevation than any other palm: they are known to occur at elevations exceeding 11,500', where there is some frost. C. utile (now C. parvifrons) was once reported to grow as high as 13,500', but this report may have been an exaggeration. Thirdly, they have extremely waxy trunks, which are remarkably hard and tough.
Ceroxylons have always been rare in cultivation. They come from perpetually cool, moist climates. Florida is too hot to accomodate them, and many places where other palms are grown are either too hot, too dry or too cold for them. However, they have been fairly successful in coastal California. Seedlings are very frost tender, which is generally the reason they have not been very successful in the Pacific Northwest, dying even in mild winters. However, older plants show significant center spear hardiness - there is even one instance of a Ceroxylon that survived the December 1990 freeze in the ground on Vashon Island, WA. (This palm is no longer there.) To learn whether Ceroxylon could truly grow here, one would need to plan on thoroughly protecting the palm until it begins to grow some trunk. This is no small task, as it may take 10 - 35 years (depending on the species and conditions) before the trunk begins to form, and during this time the trunkless palm will slowly develop an absolutely enormous head of fronds while remaining vulnerable to frost. Once the hard waxy trunk starts developing though, it is possible, though still a gamble, that Ceroxylon could recover from very hard freezes.
Ceroxylon seed is best germinated at temperatures no warmer than 60 to 70°F/16 to 21°C. They should be potted into a very light, peaty soil mix, in which they will grow slowly but steadily. When planted out, they should be grown in moderately acidic, peaty soils such as those found in undisturbed forests. They are best adapted to cool coastal climates (i.e. they might do better in Hoquiam than in Seattle), as they make the most active growth when it is rainy and humid rather than when it is warm. They should especially be tried on the middle and south Oregon coast (sheltered from salt winds); some ought to at least be hardy in Curry County, Oregon. They appreciate partial shade in inland areas, and do well in dappled shade with an overhead canopy of evergreens. For the time being they should probably be tried only in the mildest microclimates, since they would be such a pain to protect where frosts are frequent.
I would rate Ceroxylon hardiness
as follows, from hardiest to least hardy. The species that grow farthest
south in the Andes are C. parvifrons, C. vogelianum, and
parvum, which can be found above 9,000' in northern Bolivia.
So little is known about their ultimate limits, I dare not suggest actual
temperature readings for them. I must emphasize that small seedlings
are very tender: even seedlings of C. parvifrons may die at -2°C/28°F.
The first four of these species may be roughly similar in hardiness; certainly
there is not a huge amount of difference. Some species exhibit some
morphological variation and probably also vary slightly in hardiness:
C. parvifrons (syn. C. utile)
C. vogelianum (syn. C. hexandrum)
C. ceriferum (syn. C. interruptum)
Other species, including C. alpinum (syn. C. andicola) are relatively tender.