The hazy purple blue, flower-laden branches of jacarandas are so much part of November that many people think the trees must be native. They’re not, but they have been growing in Australia for more than 150 years.
Jacarandas (Jacaranda mimosifolia) are native to parts of Central and South America including Brazil and thrive across southern Australia where they are grown as street trees, in parks and as a spreading shade tree in large gardens.
The flowers are panicles of foxglove-shaped blooms each a distinctive purple-blue colour that has given us the colour jacaranda blue.
Jacarandas were originally known as ‘dream trees’, a name that captures the out-of-this-world effect of a jacaranda in full flower and often buzzing with bees. There are early mentions of jacarandas growing in James Martin’s garden, Clarens in Potts Point in the mid 19th century. Sir James Martin was a leading figure in politics in colonial New South Wales and his name is commemorated in Martin Place in the centre of Sydney.
Martin’s dream trees were most likely grown from seed brought to Sydney by sea captains sailing from South America.
Planting and positioning
Most jacarandas are grown from seed, which means there’s variation between trees. Most however develop into large, spreading trees and need plenty of space to grow. Expect well-grown trees to reach 15m high and wide. Trees that are growing in less than optimum conditions (for example where they are dry or in poor soil) may be smaller (5m high and wide).
Select a tree with a sturdy main trunk and encourage it grow to above head height before branching. Protect the tree from heavy frost in its first year or two of growth, when they are frost sensitive.
Before the flowers erupt in late spring (usually early to mid November in Sydney but later in colder areas and earlier in subtropical climates) the branches are bare. This is because jacarandas are briefly deciduous in late winter and spring. Their ferny leaves turn bright yellow before being discarded and regrow as the flowering peaks.
As the leaves are bi-pinnate – that is made up of tiny leaflets – and deciduous they can fall into gutters, drains, water tanks, ponds and swimming pools causing maintenance issues.
For these reasons the ideal situation for a jacaranda is to be planted in a garden bed in the centre of a lawn well away from paths, paving and swimming pools. In this situation the purple carpet of fallen flowers under the tree can be enjoyed without concern about the flowers becoming slippery on a hard surface and the leaves fall harmlessly to the ground.
If they are planted near a house or other building, position them to the north or west so they cast summer shade. Under plant as the tree grows with shade-loving clivia, azalea and bromeliad.
If well positioned, jacarandas need little on-going care other than occasional watering while young. Indeed pruning can be problematic as the trees react to pruning by sending out clusters of strong shoots, which grow upwards. If pruning is required, follow up the initial cut by removing these shoots, which can be cut away or even rubbed off the stem when they are young and soft.
Round woody seeds follow flowering. On young trees these can be pruned away. Seedling trees may be grown from the seeds and seedlings may appear as weeds near established plantings. These can be hand weeded.