Come on you Aussies! Want a splash of exotic warmth and colour as we crawl towards spring through the grey days of December, January and February? Acacias certainly deliver that!

When is a mimosa not a mimosa?
Strictly speaking Mimosa pudica [the sensitive plant] from tropical America is the 'proper' mimosa, the rest should be known as acacias, [a bit like when is a geranium not a geranium? - When it's a pelargonium!]. But mimosa is so much more descriptive and evokes the flowers somehow, with their powdery vanilla/almond scent and fluffiness.

Acacia are mainly native Australians, but acacia species also hail from Africa, S Texas, N. Mexico and India.
The thorny Acacia karroo is one of the invaluable staples of the veldt in Southern Africa providing a wide range of services to insects, animals and man. Acacia have also been introduced to, and naturalised in other countries, including parts of Southern France, presumably originally planted in Provence for the perfume industry where it has been used as a standalone scent and to boost violet scents.

If you are reading this and live in warmer, more acacia friendly climes, you may think why the fuss? But here in the UK the scent and cheerful yellow flower puffs are a treat to brighten the dreary days of winter and early spring. Buying the cellophane wrapped bunches with their fluffy pom poms are an ephemeral pleasure offering the promise of warmth and summer. Once out of the wrapping the fresh poms dry out fast but the scent continues to linger gently for a while.

A number of years ago I fulfilled a dream to see acacia flowering in one of their adopted places, Provence. On a day in early March the plane climbed out of a very wet and grey Heathrow and transported me to Nice which was already gently warm and sunny. The hills all around at the lower levels were covered in the yellow of acacia thickets, fantastic! I finally ended up at Bormes les Mimosas the centre for acacia addicts where many different varieties are planted around the town. I also saw freesias growing on the sides of the roads, and higher up towards the snow line, fat purple orchids and rich anenomes [A.coronaria, de Caen] - altogether a magical weekend.

In the UK in later spring you sometimes see the unexpected acid yellow flare of a well established A. Dealbata*. There is one growing in a garden near West Ealing station that you can see from the train, another in a garden near Porlock in Devon. There are probably plenty in Devon, Cornwall and Southern Ireland too, but I have never visited early enough to see them.

Hardiness is always going to be an issue with acacia, frosts can blacken and ruin the emerging buds as many are early spring flowerers in the Northern .Hemisphere. Rix and Phillips suggest -10°C is the limit for the hardier acacias [e.g. A.Dealbata] other borderliners won't take much below -3 to -5°C for short spells. As with all these things it will depend on aspect, shelter, soil etc. Some books suggest you find the warmest, snuggest most sheltered spot you can against a wall for extra heat and to ripen the new wood to get through the winter. Nice advice until you find you have a very large tree on your hands!

Jeff Irons has written to suggest that the A. dealbata to get is ssp. sub alpina*, grow it from seed and then select the smallest. With luck it will only reach about 6ft, but may get to 30ft. Ssp. dealbata is a 100ft tree that grows under even taller trees. So be warned!

For a little 'lift' on dreary late winter day visit a 'cool temperate' [Mediterranean] glass house at places like Kew or Wisley [or presumably The Eden project although I have not visited yet]. You can dream of summer for a while amongst the Acacia and citrus trees.

Some to try growing
Swamp Wattle/Wirilda, A.retinodes has hard flat long leaves [phyllodes] and smallish clusters of bobbly yellow flowers. It will flower for quite a long period rather than just in spring, eventually making a tree up to 8m. One source says it likes a little acid in it's diet another that it is lime [alkaline], drought and salt tolerant, try it and see!

Silver Wattle, A.dealbata is more often seen, it has feathery leaves and under favourable conditions in warmer parts of the UK it can make a substantial tree [see notes from Jeff Irons above], so be careful where you site it!

The cooed over Acacia is Cootamundra Wattle, A. baileyana Purpurea which has whorls of purpley feathery leaves [a bit like the parrot feather pond weed] and yellow sprays of pom poms on the tips of the branches. I have the non Purpurea which is also admired for it's glaucous greeny/aqua foliage, but I am not that fond of it, I have it in a pot so I can move it to more sheltered accommodation outside. It still gets frosted, as it is a spring flowerer this means you lose most of the flowers, looks raggedy and the flowers don't seem to be scented. Some sources have this down as one of the more borderline acacia for hardiness so possibly a much better doer inside.

I have also had A.saligna briefly, another one with the flattened 'leathery' leaves [phyllodes], but it did not like frost at all, it blackened and died very quickly. Spring flowering Blackwood, A.melanoxylon is also said to be fairly hardy liking things a bit moister generally, it is not one I have tried yet.

Leafing through Rix & Phillips 'Conservatory and Indoor Plants' Volume 1, I have seen one to lust after, 'Exeter' hybrid, huge panicles of yellow [although they don't say if it is scented or not], but to get the most out of this one a 'cool temperate' conservatory is the ideal - and I don't have one of those!

Jeff Irons suggests for hardiness in UK gardens Acacia obliquinervia. In the Taunus mountains there are specimens over 20 years old. It is at least as cold tolerant as A. pataczekii. He also grows in his garden A. nano-dealbata and A. verniciflua, both from wild collected seed taken from plants in cold areas. The latter is sometimes found growing in the trunks of tree ferns bought in British garden centres.

Growing from seed
I have grown A.dealbata [Silver Wattle] and A. retinodes [Swamp Wattle] from seed and they have come up easily when sown indoors in some warmth in spring without any pre-treatments. The A.retinodes started to germinate between 4 - 6 weeks after sowing indoors in early April without any burning or soaking. Some sources suggest soaking the seeds for a day or so in initially hot water to maximise germination. Other sources suggest a bit of a scorch will kick start the acacia into growth as they are early colonisers of burned scrub areas. The roots have an odd foxy/onion smell which you will find out when you repot them and wonder where the strange scent is coming from.

My A.retinodes or Four Seasons Acacia reached 15 feet in just under 3 years from seed, flowered its socks off all summer in it's third year and promptly died in October for no reason that I could fathom. My mother also had one from the same batch which did exactly the same thing a month earlier than mine. Still it was a luxury to be enjoyed while I had it. There is something special about sitting under your own home grown acacia in full flower.

References:

Conservatory and Indoor Plants Volume 1 [1997], Roger Phillips and Martyn Rix

Scented Flora of the World [1997 & 1994], Roy Genders

Australian Plants for European Gardens, Jeff Irons [available from the RHS bookshop]

Places to buy plants and seeds

Trevena Cross Nurseries
Having consulted the RHS Plantfinder, Trevena Cross Nurseries seem to have a good selection of Acacia and experience of likely UK hardiness.

Cottage Garden Flowers
Bob Brown's nursery in Worcestershire stocks a number of Acacia, the rather shortlived A.saligna came from this nursery [my responsibility for it's short life I must add!]

Chiltern Seeds
This seed catalogue stocks quite a number of Acacia species. In 2002 these included A. farnesiana [Sweet Wattle], A.dealbata, A.karroo, A. baileyana 'Purpurea' amongst the 15 or so listed.

Silverhill Seeds stock seeds of a range of South African Acacia's

The Eucalyptus Nurseries
Stock Acacia dealbata ssp. sub alpina and a number of others.

Images and growing information

World Wide Wattle - all you want to know about Australian wattles with lots of images to feast your eyes on!

UK - Australasian Plant Society- http://www.anzplantsoc.org.uk/index.html

Bormes les Mimosas - the centre for all things 'mimosa' in Provence, with specialist plant fairs, flower festivals and shops selling products dedicated to les mimosas.

This site [Spanish language] shows a number of the acacia grown in Spain with pictures of mature trees which gives an idea of habit and eventual size under good growing conditions.
http://www.arbolesornamentales.com/Mimosaceae.htm

Updated June 23 2003 Updated February 2007

@Kari's garden 2002 - 2007