Palms
Another essential group of plants for the exotic garden. There are a lot of palms on this list that, although not grown outdoors in this country for any length of time, have been widely grown elsewhere - especially the USA and Mediterranean regions - thus their cold tolerances are fairly well documented. This includes butia, jubea, phoenix, brahea etc and if you can give them a spot within their tolerances, they should do ok. There are other palms that are pretty new to cultivation that may possibly have some cold tolerance but no-one really knows yet. This includes arenga, dypsis, caryota, wallichia and others.
ACOELORRAPHE
Not even sure of anyone is trying this one, but it should show an amount of cold tolerance. From central America, Florida and the West Indies this is a fan palm that forms large colonies of stems to a max of maybe 6m - usually less - and becomes a confused ticket of stems topped with silvery fan leaves. grows on brackish swampland and is best with access to water underground.
ARENGA
A feather palm from Taiwan that displays an amount of cold tolerance; the leaflets are very attractive, often having a slight fishtail appearance. Slow growing and said to need heat in summer to grow at all, despite of a preference for shade, this clumping dwarf fan may be worth trying in milder gardens; mature palms clump into quite large colonies though indidivual stems only get to around 3m. (2000) Another species to try is A. microcarpa from China.
BRAHEA
The absolutely gorgeous Blue Hesper Palm from Mexico forms a dense crown leaves that are very stiff fans of silvery-blue and eventually a solitary thick grey trunk. Leaf petioles are patchily covered with a brownish fibre. One of the very, very few truely drought tolerant palms this grows in similar habitat to cacti and agaves - a clue to it's cultural needs. This is a slow grower, and a position in full sun and perfectly drained soil will allow this palm to give it's best. Extra irrigation in summer will help it along but in drainage is necessary for the wet winter soil - grown in this way it should be hardy to -8ºC or less when larger. It has become more widely available in recent years and is well worth growing. (1997)
Sometimes seen offered for sale; this is a larger, faster growing, hardier and greener palm than B. armata but nowhere near as nice. There is a whopper in the temperate house at Kew, so look at this before you think about planting one outside.....
BUTIA
An extremely attractive feather palm from Brazil and Uruguay of variable appearance but characterised by beautifully arching leaves that start off pointing skywards before curving back towards the ground again at the tips. Typically the palm has blue-grey leaves but they can vary from silvery-grey through blue-grey to pale green. Small plants in particular vary greatly in appearance from slender with long arching leaves to stocky with stubby looking very strongly erect leaves and in my view these squat youngsters will grow up to be the better looking adults. Slow growing, these will ultimately grow a trunk to 5m or so though I think they look better when they are still bursting from the ground. This is also one of the hardiest of the commonly available feather palms second only to the even slower and outrageously expensive Jubea chilensis. In rich, well-drained soil with shelter from cold winds you should expect this to weather occasional lows of -12ºC or maybe even lower and it has remarkable resilience to adversity; one of my own butias lost it's central spear two years on the trot with no lasting damage. In my opinion this should be more widely planted - feather palms by virtue of the fact that there are so few hardy ones just SHOUT exoticism! (1997)
There are other species of butia often encountered. Butia yatay is now available as larger trunked specimens which, though superficially similar to Butia capitata will ultimately be a lot taller and perhaps, in relative terms, better value for money than the rarely available trunked B. capitata specimens. They should prove to be of similar hardiness and tolerance, though it has to be said haven't been tested. Other names are sometimes seen - B. eriospatha, paraguayensis and some others; they are all very much alike and really you need to be a fully paid up anorak to want to grow them.
X BUTIAGRUS
Something of a Holy Grail, being one of the most desirable palms with potential for growing in temperate climates. This is a rare beast - a bi-generic hybrid of two related palms; Butia capitata and Syagrus romanzoffiana. In looks it is somewhere between the two being a feather palm that is somewhat stockier than syagrus but more elegant than butia, almost resembling a coconut palm or howea, with a potential hardiness closer to butia than syagrus. I have only ever seen one large specimen offered for sale, for a four figure sum.
CARYOTA
Chinese Fishtail Palm. This race of palms are really pretty, basically bi-pinnate feather palms whose leaflets are shaped like fishtails. This is one of two potentially hardy species that are probably worth trying in the most sheltered UK gardens - certainly in central London or the Southwest.
This is the name given to what is presumed to be a form of Caryota urens that has been found growing at high altitude in the Indian Himalaya and is probably the most cold hardy of the genus. The key to growing this would appear to be annual protection until too large and LOTS of food and water in the growing season - caryotas in general and greedy palms and should respond to being well fed. My own experience with this palm is less than inspiring, the whole plant being defoliated at -2ºC and the subsequent re-growth has been slow. Still, early days and certainly worth persevering as it should get hardier and faster growing with age. (1999)
CEROXYLON
A few species of tall, elegantly beautiful, high altitude South American feather palms that have some cold hardiness potential, growing at extreme altitude and being exposed to cold and damp conditions for much of the year. Never too cold, never too hot, almost always sunny and warm during the day and cool at night. Species available include C. alpinum, ceriferum, ventricosum and possibly the best bet of all Ceroxylon parvifrons. It remains to be sen if they can adapt to growing in the UK - I would imagine the Southwest of England or Ireland would give them the best chance.
CHAMAEDOREA
One of the hardiest species, this feather palm will prefer moist soil in shade - like all chamaedoreas they burn badly in sun. It forms a cluster of bamboo-like stems to 3m and small pinnate leaves of dull green. It seems to have a lower tolerance around -5ºC, though this remains to be tested more widely to be set in stone. Definitely worth a go in sheltered gardens anyway - my own plant has performed 'reasonably well though I keep it protected in winter at the moment. C. erumpens and sefritzii are both similar but less hardy. (1999)
The hardiest species and worth a try in most exotic gardens, this seems variable in form - generally forming a low sparse clump but every now and then a plant will grow upwards with a slim trunk to around 3m. The pinnate leaves are quite dark and leathery in appearance and it has been known to survive -8ºC with only minor damage. Reports from the Pacific Northwest in the US indicate that it could be a good deal hardier than this once established, so all in all quite a good prospect. Like the others it needs to be grown in shade, where it's feathery form will complement ferns and contrast with the other large leafed denizens of your jungle floor. (2000)
CHAMAEROPS
One of only two palm species native to Europe, this can be seen growing on rocky hillsides of western Mediterranean coastlines. It is extremely variable in appearance, but typically more shrub than tree suckering quite prolifically to form a dense rounded mass of trunks with a tight dome of green fan leaves. The leaf petiole is armed with vicious spines (a distinguishing feature when compared to the other commonly grown palm - Trachycarpus fortunei) which are EXTREMELY painful if they become lodged in your skin. Some forms cluster even more profusely, some form a single trunk, some have a more intense silvery coating beneath the leaf
DYPSIS
JUBEA
LIVISTONA
LYTOCARYUM
NANORRHOPS
PARAJUBEA
PHOENIX
PLECTOCOMIA
RAVENEA
RHAPIDOPHYLLUM
RHAPIS
RHOPALOSTYLIS
SABAL
SERENOA
SYAGRUS
TRACHYCARPUS
TRITHRINAX
WALLICHIA
WASHINGTINIA
CORDYLINE
CYCAS
ENCEPHALARTOS
MACROZAMIA