Trachycarpus, the frost hardy evergreen palm for UK gardens
One of the mainstays of any tropical or exotic garden is the palm tree. The term palm does cover a wide range of plants and probably the most reliable in the UK climate. Typically they have green fan palm leaves although some of the newer introductions are blue-green with white or silver undersides to the leaves.
This palms got form
Although we refer to different species, technically many are just other recognised forms, especially of T. fortunei. The confusion comes from some different species/forms being mistaken for similar ones when they were actually a new species and vice versa.
They are remarkably hardy of which the most proven hardy in the UK is fortunei which has been know to withstand temperatures in 2010 and 2011 lower than -15°C. If you want reliability then this is currently the best species to choose.
A palm tree for UK gardens
The Trachycarpus genus the most famous and most widely available of which is Trachycarpus fortunei, the Chasun or Windmill palm. They will survive quite happily across most of the UK and are easy to grow making them a must have in your garden. The larger specimens will give your garden that instant Mediterranean or Tropical look.
This palm is characterised by it's slender fibrous trunk and circular or semi circular palm leaves with many leaflets. On adult trees it can put on a foot of trunk growth in a season and tend to grow slowly in the first few years or when in ideal conditions. However it has been said that the slower they grow the more hardy and resilient they are.
What palm should I buy?
If you are looking to buy a Trachycarpus palm tree then the most widely available and also tried and tested in the UK are fortunei and wagnerianus with the former being a good buy if this is your first palm. It is also less fussy, will grow almost anywhere and will not need any winter protection in most parts of the UK. Other varieties are not widely available and some are very difficult to get hold of and your best source is at a specialist nursery.
The Needle Palm (Rhapidophyllum hystrix) is the only palm that is hardier taking temperatures down to -20°C.
Needle Palm (Rhapidophyllum hystrix)
Whilst the Needle Palm is the world's most cold tolerant palm, it prefers really hot weather to grow so grows at a slow rate in the UK hence it tends to cost more than other palms. This is why Trachycarpus fortunei is more popular as it prefers the milder cooler climate we experience in Britain and so grows much faster.
Trachycarpus fortunei (Chasun Palm, Windmill Palm)
Affectionately referred to as a Trachy this is the most widely available and most commonly grown cold hardy palm albeit not common per se. The Fortunei species is the one we know most about in the UK so are sure of its hardiness and performance in gardens.
It can grow at a rate of about a foot of trunk a year and despite what you may think about this tree it grows best in cooler weather and actually dislikes extreme heat. It can grow to 20 metres but it may take 60 to 70 years to reach its full height. The fan palm leaves can reach up to 2 metres in length and can have straight or drooping tips as this can vary.
Trachycarpus fortunei care
Under normal circumstances you should not need to provide any protection in winter. However to be on the safe side it would be sensible to wrap the crown and trunk of your palm with fleece if you are experiencing a prolonged period of sub zero temperatures. Prolonged periods where the daytime temperatures remains freezing can lead to freezing right through the trunk.
As with all plants they benefit from feeding and watering in prolonged dry spells. There are specialist palm feeds you can buy but you could also just use well rotted manure or liquid feed. Feeding throughout the growing season will encourage faster growth.
Trachycarpus wagnerianus (Miniature or Dwarf Chasun Palm)
Also referred to as a Waggie this is now officially referred to as Trachycarpus fortunei var. wagnerianus. A slow grower. It certainly is very different with smaller stiffer leaves and generally looks tighter and tidier. This is considered more preferable by many growers due to its smaller leaves that are more resistant to winds.
Although slower growing it will eventually grow as tall as T. fortunei and you should expect it to reach a maximum height over a longer period. If you have a young specimen then you may not expect it to take off in terms of growth until its second or third year as it likes to put its energy into root development first. It is also believed that in the UK at least it is also not as hardy as there were many reports of Waggie losses in gardens where Trachy specimens remained untouched by very cold and prolongled spells such as winter 2010 and 2011.
Trachycarpus fortunei x wagnerianus
A cross between T. fortunei and T. wagnerianus with the same frost hardiness as both parents and a mixture of characteristics. There are a number of different crosses in existence as this genus readily cross pollinates naturally as well as nurseries producing hybrids that are available for sale. Other popular crosses include wagnerianus x fortunei (female x male) and you may also find other trackie hybrids being offered for sale, especially with the increasing availability of the newer varieties that are being introduced.
Trachycarpus fortunei 'Darjeeling'
This Darjeeling form is from North East India in the Kalimpong region rather than China. Again just as hardy as T. fortunei but said to be slightly stiffer and more compact but possibly not as much so as the cross pollinated varieties.
In its native Darjeeling it grows at 2000 metres and so some sources claim it can withstand lows of -21°C (-10°C if pot or container grown) but this is debated as most of the hardy varieties we grow in the UK come from the Himalayan region at 2500-3000m. It can grow to 10 metres in height.
A newly introduced species to the UK from China of which there appears to be Stone Gate form and Golden Lotus form. The difference between the two seems to be leaf colouration where the former is greener and the latter is more of a blue green. Other than this they appear to be identical and both have the iconic white underside to the leaf which is what makes these desirable amongst enthusiasts.
There are not many who are growing T. Princeps in this country but there hardiness is considered to be less so than other species possibly down to -10°C or -15°C a push. In the wild they grow to 10 metres but remains relatively thin trunk. With age the brown fibre on the trunks that are usually associated with this genus comes away from the lower part of the tree.
Trachycarpus fortunei 'Naini Tal'
Nainital is a recently discovered species from Northern India at around 2000ft so is though to be quite hardy. In looks it appears to be similar to T. fortunei but larger and has a faster growth rate. They also can suffer wind damage so is not as wind proof as T. wagnerianus.
This species were originally sold as T. takil until it was discovered they were actually T. nainital. Another difference is its tendency to shed the fibrous part of the trunk naturally so if you prefer a stripped trunk then you may prefer this. It is also reportedly hardier although as yet there have not been many reports to confirm this.
Trachycarpus takil (Kumaon or Kalamuni Palm)
Many consider this to be the must have Trachycarpus due to its frost hardy nature, stiffer more wind resistant leaves and the leaves are silver underneath. Growers have commented that they get much less wind damage and maintain their shape. Will lose the fibrous hair from the trunk as it grows.
The slowest growing and smallest of all the genus growing to about 3 feet in height. It is almost trunkless and to me superficially looks very similar to Chamaerops humilis. Adult palms have a bluish tinge to the leaves. Very hardy down to -17°C.
Trachycarpus fortunei 'Hasan'
Shorter thicker stem, smaller brighter green fronds. Very hardy down to -17°C.
Trachycarpus fortunei 'Kiril'
Hardier variant from Bulgaria. Very hardy down to -18°C.
Trachycarpus fortunei 'Misan'
Rare in the wild, smaller mini version with green to yellow fronds as small as half the normal size. Great for the smaller garden. Very hardy down to -17°C.
Trachycarpus fortunei 'Tesan'
Rare in the wild, a shorter thicker trunk and broader fatter fronds taking temperatures as low as to -17°C to -20°C as reportedly hardier than the standard Trachy.
Trachycarpus fortunei 'Winsan'
Rare in the wild, fronds are made up of leaf segments that tend to meet to form a circle. Smaller than a standard Trachy and faster growing. Cold tolerant ranges reported to be in the -6°C to -8°C range where more optimistic reports are -12°C to -17°C
Fronds have two or sometimes 3 leaf segments joined together. Fronds are a deep green and more leathery and have a gloss appearance. Not as hardy but still taking temps down to -10°C.
Trachycarpus martinus are less hardy than others in the species and can start to become damaged below -3°C. There have been reports of specimens surviving down to -10°C but in general -6°C or -7°C is about the limit.
Whilst they are elegant and beautiful specimens you will have to regularly protect them over winter in the UK. Unless you are a collector or an avid Trachie fan I'd stick to one of the many others becoming available in the UK that are much hardier and more suited to the British climate.
Trachycarpus latisectus (Windamere Palm) now known as Trachycarpus martianus var. latisectus
Distinctive for its 5cm wide leaf segments and large glossy leathery fronds. Less hardy to about -7°C or -8°C.
Trachycarpus martianus var. 'kassia hills' (Khasia Hills Fan Palm)
Often described as graceful and beautiful palm this is a slender and bare fibreless trunk and deeply cut large elegant fan palm leaves. Not as Hardy taking moderate frosts down to somewhere between -3°C and -6°C so not recommended unless you plan to protect in winter.
Trachycarpus martianus var. 'Nepal'
Smaller and fewer segmented darker green leaves compared to latisectus but slightly hardier and slightly more tolerant of dry soils. -6°C. Will need protection in winter in the UK to keep it looking good.
Trachycarpus oreophilus (Thai mountain fan palm)
A bare fibreless trunk and compact crown of large fanned palm leaves with white undersides. Hardy to -8°C but mature palms reportedly hardier -10°C to possibly -15°C but unproven in the UK.
Similar to T. princeps and T. oreophilus but with silver white undersides but lacks the bluish tinge. Stiffer leaves and numerous leaflets. Hardier alternative to T. oreophilus down to -17°C.
Trachycarpus sp. Nova (Green princeps)
Reportedly the fastest growing of its genus although not as hardy taking temperatures down to -6°C or -7°C. The leaves are finely divided and softer and not as stiff and so susceptible to damage in UK winds.
Trachycarpus ukhrulensis(T. sp. 'Manipur', T. sp. 'Naga Hills')
Stiffer dark green leaves with silver white undersides. The large palmate 4 foot leaves have 68-71 segments making the leaves appear more dense. As hardy as fortunei at -13°C to -17°C.
The one leaf seedlings start to suffer damage at -10°C, but are fine below that. If a palm is established and healthy they are good to -10°C, but a mature width, healthy, established palm is good to nearer -15°C
- Dave Brown, Hardy Tropicals
Trachycarpus Winter Frost
I've added some pictures taken after frosts have formed on the palm tree leaves. The stiffness of the Trachycarpus wagnerianus palm fronds are shown off well covered in white frost and don't mind the subzero temperatures.
The stiffer fronds of the dwarf Chasun palm are similar to Chamaerops in strength but are larger and have no spikes on the stems.
Palm tree leaves especially the palm fronds of this cultivar are very architectural keeping their characteristic palm like shape. The frost highlights their organic shape and adds a real exotic look even in the depths of winter.