Acacia

The best known Acacia in this country is Mimosa (Acacia Dealbata).  Advice has been sought from different experts in Australia on the viability of certain relatively high altitude provenances to enable the wider planting of Acacia in the U.K.

Provenance is the name given to a very particular location of parent trees.  It is important because those trees will impart particular hereditary characteristics to their progeny that will enable them to flourish in parts of the world with a similar climate.

Conventionally they are grown outdoors in Devon and Cornwall and sheltered parts of the South and West coast of England.  However, the high altitude provenances offer promising hardiness for planting outside in other sheltered areas and are tolerant of minus 10°C or lower.  The subalpine provenances of Acacia promise to be even more frost hardy.  It is believed that these provenances have not been grown here until recently.

Some available species have not been included because they are of poor form and no ornamental value.

See Acacia in the Our Plants section for species available.

FLOWERING

Many species have the similar delightful perfume and cascading flowers of Mimosa and are various shades of yellow.  Flowering usually commences after 2 or 3 years growth but it is recommended to pinch out the young flowering buds until the plant is 5 years old to encourage leaf and stem growth.

LEAF COLOUR

There is a great variation of leaf shape and colour and they are sought after for cut foliage, particularly the fern-like leaves. They vary between glaucous, creamy yellow, silvery-white, red or purple.  The leaves of Acacia in many species after the juvenile stage become reduced to a development of the leaf stalk: known as phyllodes, they are flat, leaf-like and often of considerable size.

INDOOR SPECIMENS

The smaller species make excellent greenhouse or conservatory plants and are also successful pot specimens, where flowering is enhanced by being brought out of doors between June and September.  To encourage branching and discourage 'legginess' pinch out the leader whilst the plant is small and repeat this throughout the growing season.

FLOWER ARRANGING

If cut back hard, Acacia will send out root suckers but this cannot be relied upon for regeneration.  Similarly, some species will send out coppice shoots from the stump but they seldom survive.  If the adult phyllodes or leaves are desired for flower arranging a maximum of a quarter of the tree should be cut each year, leaving the remainder to regrow.

COASTAL PLANTING

Usually the provenances available in this country are from the lower coastal areas of Tasmania and New South Wales where they experience to some extent coastal winds but have lower frost tolerance.  All offered are from inland areas and have higher frost tolerance but lower tolerance to salt winds.  However, Acacia melanoxylon and pravissima show promise for coastal planting whilst also exhibiting higher frost tolerance.

PLANTING

Acacia are all evergreen leguminous nitrogen-fixing trees and shrubs; they will pick up the rhizobia from contact with soil when planted, thereby generating their own nitrogen fertility.  They require direct sunlight and an open loam, peat or mildly alkaline soil.

Outside planting is best done in April, May or June to allow for maximal establishment before any heavy winter frost.  If ordering in the autumn they should be over-wintered in a greenhouse or conservatory.  They will make some useful growth before planting out in the spring.

They should not be planted in frost pockets or on exposed sites.

Growth rate is comparatively fast and varies.  Some of the tall species when established will grow at up to 5ft a year.  Pinch out the growing tips from the first year to encourage more bushy specimens.

Please remember Acacia do not occur at such high altitudes or tolerate the amount of cold or exposure that some Eucalypt species do.  However, every effort has been made to offer promising provenances.  We can provide you with plants that will give you the greatest opportunity of successful Acacia growing ever offered in the U.K