Cold Hardy Pink Flowering Eucalyptus

Cold Hardy Pink Flowering Eucalyptus
Asessing cold tolerance of E. leucoxylon 'Rosea'

Gustavo Iglesias Trabado
GIT Forestry Consulting - Consultoría y Servicios de Ingeniería Agroforestal - www.git-forestry.com - EUCALYPTOLOGICS

One of the ornamental features of Eucalyptus has to do with their flowers. Shape, size, colour. Typical common species overseas usually have white stamens, and can be attractive both when individual flowers are of a big size, or when small sized flowers are well arranged in attractive clusters. But there are other possibilities.

Fig. 1: Pink flowered Eucalyptus leucoxylon 'Rosea' in bloom in the UK.
(Photo courtesy Matt Smith)

Red or pink flowers are not too common, but some Eucalyptus do have them. A classical example is Corymbia ficifolia, the Red-Flowering Gum. A striking small tree which flowers profusely. But for those trying to add them to garden designs in cool temperate climates of a maritime type, there are other options with a lightly higher tolerance to cold.

Among these, some of the subspecies of Eucalyptus leucoxylon, which as in the pictured example, can be successfully cultivated and subsequently bloom at high latitudes as those of the United Kingdom or Ireland.

At the suggestion of some keen gardeners Growing On The Edge, we prepared an indicative "cultivation map" for this species in the British Isles.

Fig 3: Suitability of E. leucoxylon ssp. leucoxylon for outdoor cultivation in the British Islands.
(Click image to enlarge)

Inevitably, this map is not a detailed one and is based on just one of the main parameters with importance for plant acclimation, which is extreme minimum temperatures reached for a certain area along a period of time. If we start removing from the coloured areas all the unsuitable microclimates (too windy, too salty, too exposed, too boggy, too chilly even if just once per winter, too shady, etc) the suitable real area for cultivation would reduce considerably. Still, it can be an indication for those willing to add red coloured blooming eucalypts to their gardens.

In this case some caution is yet needed: despite its cold hardiness is higher than for the Western Australian Corymbia ficifolia, a rare Mediterranean eucalypt species, it is not infinite.

Fig. 3: Tolerance to frost in an E. leucoxylon 'Rosea' ornamental trial in the tablelands of Galicia, Northwestern Spain. (Click image to enlarge).

Our own trials with this type of eucalypt in the tablelands of Galicia (Atlantic maritime climate with a tendence to harsh frost events), where oceanic influence fades, do suggest that Eucalyptus leucoxylon 'Rosea' reaches its cold hardiness limits around -7ºC. This would be roughly equivalent to suitability for safe cultivation in the mildest part of Atl1 Zone, or in USDA Zone 9a and less harsh areas. Our results in the Iberian Peninsula do corroborate earlier trials done by Dr. David Robinson at Earlscliffe Gardens near Dublin, the Northernmost known latitude at which this and several other rare species have bloomed.

If you get to know of any case of successful horticultural use of this pink flowering Eucalyptus at higher latitudes than Dublin, please do not hesitate contacting us!

Contact GIT Forestry Consulting - Eucalyptologics

We already found the Northernmost Flowering Eucalyptus, and now it is time for the Northernmost Red Flowering one!. And for the matter, you are also welecome to contact us if you see and photograph them growing and blooming elsewhere. The most specimens tracked down, the better future recommendations for growers worldwide!

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© 2008 Gustavo Iglesias Trabado. Please contact us if you want to use all or part of this text and photography elsewhere. We like to share, but we do not like rudeness.

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