Several will live in warm sheltered corners, while others will survive in cool glasshouses. The small spherical flowers, which grow in huge clusters, are actually made up entirely of stamens: mimosa flowers have no petals. Some mimosas have no leaves, either. The leaf-like structures are phyllodes, flattened triangular leaf stalks which grow straight on the branches.
Acacia dealbata, the silver wattle, is one of the easiest to obtain and easiest to grow in this country. It is the same one which is often seen by the side of the road in the south of France. The Mediterranean mimosas can blossom at other times, too. They have fern-like silvery leaves and their scent makes up for the rather harsh yellow flowers.
Acacia dealbata is worth trying in a sheltered spot anywhere in the south of England, where it can grow to 30 feet. In suitable conditions, mimosas grow fast: at Abbotsbury Sub-Tropical Gardens in Dorset they grow some species from seed - in less than a year these are three feet tall and ready to sell.
There are 1,500 different species of Acacia, all of which originated in Australia and Africa. Many need enough room to grow into a small tree, will sulk if they are cut down too much, and won't stand frost - so there is a limited choice for gardeners without double-height conservatories.
If you're on the trail of hardy mimosas you could try A retinodes. This is an attractive tree with narrow willow-like leaves, which flowers in late summer. But the best of all is probably A pravissima.
This is one which has phyllodes instead of leaves. They are silver-grey and arrow shaped, growing all along the branches, so they make good cut foliage even without the flowers. The flowers are a softer yellow than the silver wattle, and clusters of them are slightly smaller. They are spread all along the branches, so rather than making a solid block of yellow, the overall effect is of a mingled yellow and soft green. The branches flow in elegant arches, and seen from underneath, with a backdrop of a clear spring sky, the effect is totally magical. My plant flowered in January last year, but this year it is just about to flower as late as April, presumably because of the cold weather at the beginning of the year.
For a glasshouse, one of the best is A baileyana. It has frond-like, blue-grey leaves, and clusters of flowers in the early spring. Several nurseries now offer a cultivar, A baileyana Purpurea, which has a mauvish tinge to the young shoots. It needs the shelter of a conservatory, and a large pot of John Innes No 3, plus regular feeding. Acacias are part of the pea family, and produce a certain amount of nitrogen on their roots, so they don't need quite so much feeding as some other pot-grown shrubs. As Roger Clark, of Greenway Gardens near Brixham in Devon explained, they need well drained soil, and plenty of room to grow. If they are cut back too much it may prevent them from flowering freely.
As with many other plants, trial and error is proving that more and more mimosas will survive in this country. A flower which 20 or 30 years ago we expected to see only on holiday, is now being persuaded to thrive here. And as growers experiment with species, we can expect the range of mimosas to widen over the next few years.
Greenway Gardens, Churston Ferrers, Brixham, Devon TQ5 0ES (01803 842 382) and Abbotsbury Sub-Tropical Gardens, Abbotsbury, Nr Weymouth, Dorset DT3 4LA (01305 871412) both specialise in unusual and tender trees and shrubs and have several mimosas on their lists.Reuse content