Commonly known as ‘Fern Tree’
The streets of Buenos Aires are lined with avenues of this splendid purple-blue flowering tree which originates from Bolivia and Argentina. It is even more splendid with its foxglove-like flowers than Paulownia tomentosa and it is therefore depressing that it can only really be grown in frost free areas of the UK or in large greenhouses. Trees have got established in the warmth of London but they seldom grow and develop to flowering size before being cut back by frost. There is a mature tree (confusingly) in the Mediterranean biome at the Eden Project which does flower and set seed there. Otherwise you may only experience it on holiday in frost free Mediterranean countries.
Despite J. mimosifolia being frost tender it is a popular plant by mail order from the nursery and many people are giving it a go!
As a spreading deciduous tree it will grow, in warm climates, to about 50ft. The leaves are up to 18in long and composed of many fern-like leaflets. The flowers appear in spring to early summer in broad panicles 8-12in long. The blue flowers have a white throat and generally precede the new leaves.
Under glass the tree will thrive in loam based potting compost in full light with good ventilation. You will find that it grows extremely quickly and is probably best regarded as an attractive foliage tree. It can be used for this purpose in summer bedding. Some flowers will form even in container grown plants indoors but this may take several years, a bit of starvation and a hot summer or two. As with many tender greenhouse trees they become more resilient when they develop a woody trunk and can then reshoot effectively after any dieback caused by frost.
