We have one of the best climates in the world in which to grow Jacaranda mimosifolia (outside of its native home of Brazil) - it doesn't like very cold or very hot equatorial climates, so ours is just right. Journeys by train or ferry around Sydney when they are in bloom show a city simmering in a purple haze.
Jacaranda mimosifolia belongs to Bignoniaceae, the Bignonia family, which contains many of the (often vigorous) climbers that we enjoy in our gardens. The characteristic flowers of the family are large and tubular, with flaring mouths. The Jacaranda has mauve-blue foxglove-like blooms, held in large panicles, appearing around late October and lasting for a number of weeks. There are white cultivars around, but to me that defeats the purpose of growing the tree in the first place. The tree has finely divided, fern-like foliage, and grows to a height of 12 - 15m, forming a broad dome, making it very useful as a source of summer shade.
The foliage is shed around August, then reappears in late November or early December. The dramatic appearance of the flowers is best on trees where the leaves come after flowering rather than at the same time: this seems to vary from one tree to the next and is also possibly a climactic phenomenon: a drier season sees the leaves appear later. The bark has a lovely elephantine texture, and the tree is best left unpruned, once it has been trained to a single main trunk, as often ugly vertical shoots will arise from the points at which it was cut. It likes a sunny, well-drained position in the garden.
The down side of the tree is that it will often self-seed via its woody rounded seed pods, so you need to be vigilant in removing baby seedlings, unless you want a forest of Jacaranda. It does need a bit of space, so is not really suited to modern suburban gardens. It is also difficult to establish garden beds nearby to the greedy, shallow roots of the tree. Another negative aspect is that if the flowers fall on paths they can become very slippery and hazardous for those walking on such a surface. For that reason, they are often banned in retirement villages! But for all that, I would never want to be without one in my garden. When the lawn is smothered in its fallen petals, it is one of the highlights in our Sydney gardening year!
To see many beautiful old Jacaranda trees, visit Callan Park in Sydney's inner west in early November.