Palms are associated with holidays and tropical climates. But within the large group of these primitive plants some species grow naturally in temperate climate zones. With some tricks, these species also can be cultivated in our climate and give an extra dimension to our outdoor space.
Distinction can be made between fan-shaped leaves and species with feather-shaped leaves. The strongest species have fan-shaped leaves. On the Internet stories go around about hardiness to -20, but these data should be taken with a grain of salt. A prolonged period of frost without snow cover, with a drying northeast wind and sun may cause more damage than -10 overnight or at -20 in a dry environment. A palm tree in a pot is never winter hardy.
Trachycarpus fortunei (Chinese windmill palm) is a trunk forming fan palm. A laboratory study concerning frost resistance (Princeps journal) shows the root system (-2 to -6) is the weakest link in combination with the growth spear (-8 to -10). In our garden mature plants survived temperatures below -15. Trachycarpus origins from relatively cool (mountain) areas with lots of rain, fog and clouds. Mature trees in the garden with approximately 1 meter trunk start to bloom every year. Seed production is possible if you have a male and female specimen in the neighborhood which bloom at the same time. At the nursery young plants are available but also large plants we import from winter cold areas in the Pyrenees and northern Italy. You can recognize good quality from thick stems, short leafstalks and compact leaves. Recently the market is being flooded with cheap plants grown in warm climates such as southern Spain, Brazil and South China. The hardiness of these plant often is very disappointing!
Trachycarpus wagnerianus (Japanese fan palm) has rigid, round leaves with rhythmic cuts on the petiole. This plant often has a white (fiber) leaf edge. The leaves are significantly smaller and more compact compared to its Chinese brother. This makes its wind resistance better. This palm also forms a trunck in time. Note that palms in pots are much less resistant to frost ! Both the Japanese and the Chinese fan palm can only be propagated by seeding. This may cause minor differences in growth habit, growth height and even winter hardiness. Both young plants as large ones are usually in stock.
Sometimes also rare and unusual species from N-India and China are available at the nursery, such as Trachycarpus princeps, Trachycarpus sp. ‘Nova’ Trachycarpus ‘Nainital Hill’s’, Trachycarpus takil (Kalamuni) and Trachycarpus sp. ‘Manipur'.
Yucca’s (Agavoideae) are originally drought tolerant plants from North America. Typically is the architectural rosette growth habit and sword-shaped leaves. There are stem-forming species which may or may not branch out regularly and there are low, clustering species. Most Yuccas do not flower every year.
Yucca recuvifolia (palm lilly) is a strong stem forming yucca from the western coasts of North America. This species is easily recognizable by the reverse curve form of the leaf. The long leaves are blue green to sea green color.Yucca recurvifolia usually grows for several years in succession in a rosette. After the first flowering the plant branches into two or more new rosettes. In the long run this creates a multi-stemmed plant with several rosettes.
Yucca gloriosa is also stem-forming with more rigid leaves compared with Y. recurvifolia. Y. gloriosa has large stately blue rosettes with stiff green leaves which turn on very exotic.
Yucca gloriosa 'Variegata' is a yellow variegated variety. This cultivar has leaf edges with a broad yellow band. It is a very attractive eye-catching plant. Particularly suitable as a solitary on a sunny spot.
Fascicularia bicolor subsp. bicolor ‘(Bromeliaceae) from Chile is probably the hardiest bromelia. The plant is about 30-50 cm high and forms dense clusters of rosettes that turn red after a few years and show beautiful blue flowers in the center. Best to plant on a drained soil. There is a smaller narrow-leaved form in circulation named subsp. canaliculata. We have obtained Subspecies bicolor from the collection of Het Loo Palace and is usually in stock. Because the leaf rosettes can start rotting because of excess water in winter, planting in an angle or vertical planting is recommended.
Dracaena draco, dragon’s blood tree from Canary Islands looks like a yucca, but is botanically different. It grows slowly into a thick stem with a single crown. Available plants are grown from seed. Treat like a conservatory plant during winter.
Cordyline australis from New Zealand forms a narrow leaved rosette on stem and can in the course of the years, more and more branching. There are several cultivars with variable leaf colors. The hardiness is limited so it is not a reliable garden plant for our climate. Though nice as an accent plant in the garden. Especially the (dark) red forms are very nice. Cordyline indivisa can tolerate more frost but is hard to come by.
Phormium (New Zealand flax) is an interesting architectural, stylistic evergreen plant and is more hardy compared to Cordyline. The big green form is growing over 15 years in our garden. The red leaved form 'Atropurpureum' and 'Bronze' are a bit more vulnerable but also survived many winters. Phormium is a member of the family of agave and yucca, although the sword-shaped leaves are much softer. The huge inflorescence has a purple to black stem from 2 to 3 meters tall with groups of reddish long tubular flowers which among others are visited by moths.
Astelia from New Zealand looks a bit like Phormium, but smaller in all parts. Astelia nervosa ‘Westland’ is a mountain form and one of the strongest. Astelia chathamica 'Silver Spear' and 'Silver Shadow' is perhaps the most beautiful with silver-white leaves. Both must be protected at temperatures below -10.
Finally, I would like to mention Dianella tasmanica. This evergreen, Tasmanian plant is about 40-60 cm high and spreads slowly by underground rhizomes. In summer the nodding, star-shaped blue flowers appear in branched panicles up to 1 m tall, followed by shiny, deep blue berries. A very nice plant for sheltered areas. Some protection during hard frost increases the survival rate.