Cultivated Plants in Flower outside at Kew in Early January, 1975

Abstract

The almost frost-free autumn and winter of 1974-75 in Western Europe had a profound effect on plants growing outside. About the turn of the year the most noticeable effects at the Royal Botanic Gardens, Kew, were the exceptional prolonging of the summer-flowering species and the early opening of spring flowers. Winter-flowering plants also commenced early and some had a comparatively short flowering season. The purpose of this paper is to list and analyse the species that were recorded in flower at Kew during the first thirteen days of 1975. The exceptionally mild wet weather continued through December, January and February and Meteorological Office tables show that at Kew these winter months had the highest average temperatures since 1921, and in the country as a whole since 1869, although this is not to say that the effects were the same as in 1974-75, when spring was brought forward into January with species that would normally be out in late February or even March. Yet it is worth noting that, apart from Europe, the Northern Hemisphere as a whole has been experiencing consistently lower winter temperature means for several years. The succession of early springs in recent years, however, is exemplified by my own phenological records of flowering dates. For example the almond (Table i), in spite of a slight set-back in 1972, shows a marked tendency to flower earlier from 1969-75. The spread of commencement of flowering of this same tree since 1963 extends from 28 January 1975 (day 28) to II April 1963 (day I oI)-a difference of 73 days!