January Flowers: Acacia

Acacias are trees and shrubs famous for their fluffy balls or spikes of bright yellow flowers, which in some kinds appear in the middle of winter. In Australia, where most acacias grow, they are called wattles, and one kind sold by florists as “mimosa” is a favorite January flower in Europe.

Scientific Classification & Quick Facts

Common name	Acacia
Scientific name	Acacia
Kingdom	Plantae
Phylum	Tracheophyta
Class	Magnoliopsida
Order	Fabales
Family	Fabaceae
Type	Flowering tree or shrub, called wattle in Australia
Native range	Australia, Africa, the Americas and elsewhere
Colours	Cream or yellow; rarely purple, white or red
Flowering season	Winter into spring
Special feature	Flattened leaf stalks (phyllodes) work as leaves

What Is an Acacia?

Acacia is a large genus of plants in the pea family (Fabaceae), so acacias are relatives of beans, peas, and clover. There are roughly 1,000 species, and the great majority are native to Australia, making it the largest genus of plants there. You can read about the big African-style trees on our acacia tree page.

For a long time, many thorny trees in Africa, Asia, and the Americas were also called acacias. In 2005 botanists decided to split the group, so most of those are now placed in other genera, such as Vachellia and Senegalia. Many people still call them acacias, though.

The name comes from the Greek word akis, meaning “point” or “thorn,” because many of these plants have sharp spines.

Acacias in History and Culture

In ancient Egypt, acacia wood was used for boats, furniture, and tools, and the tree was linked with the myths of Isis and Osiris and with ideas about life and rebirth.

In Australia, the golden wattle (Acacia pycnantha) is the national floral emblem, and its green and gold colors inspired the country’s sporting colors. National Wattle Day is celebrated on September 1, at the start of the Australian spring.

In southern France and other Mediterranean areas, the silver wattle (Acacia dealbata), known as mimosa, blooms from January to March. Its fluffy yellow flowers are so loved that some towns hold mimosa festivals in February.

What Does an Acacia Look Like?

Some acacias have feathery leaves that are divided many times into tiny leaflets, a pattern called bipinnate. Many Australian acacias, though, have no true leaves once they are grown up. Instead, the leaf stalk becomes flat and wide and does the leaf’s job. These leaf-like stalks are called phyllodes.

Phyllodes often hang or stand on edge, pointing up toward the sky. That way the strong midday sun hits only their thin edges, which helps the plant avoid overheating and losing water in hot, dry places.

Acacia flowers are tiny, with very small petals that are almost hidden by many long stamens. That is what makes each flower head look fluffy. The flowers are packed into round balls or cylinder-shaped spikes. Most are yellow or cream, but a few are more unusual, such as Acacia purpureopetala with purple flowers and a red-flowered form of Acacia leprosa called ‘Scarlet Blaze.’

Growing Acacias at Home

Many acacias are among the showiest flowering trees for warm, dry gardens. In late winter and early spring, many varieties suddenly burst into masses of golden balls and spikes.

Most acacias like full sun, well-drained soil, and mild winters, and many cannot survive hard frosts. In cold climates, grow them in pots and bring them inside for the winter. Some acacias spread very easily and have become invasive weeds outside their native lands, so check with a local garden center about which kinds are safe to plant where you live.

Harvest the Seed Pods

Acacia seeds grow in pods, like peas. Depending on the species, the pods may be a couple of inches long or longer, with several seeds inside. Collect the pods when they turn brown and dry. If you shake a dry pod, you can often hear the seeds rattling inside.

Prepare the Seeds

Photo by: Danielle Langlois

Split open the pods and pick out the hard, dark seeds. Clean away any bits of pod. If you are not planting right away, store the seeds in a labeled envelope or jar in a cool, dry place.

Acacia seeds have a very hard coat that keeps water out, so if you just scatter them on soil, most will not sprout. In nature, fire or heat often cracks the coat. To copy this, ask an adult to pour hot, just-boiled water over the seeds in a cup and leave them to soak overnight. Good seeds swell up. Seeds that float are often empty and can be thrown away.

Plant the Seeds

Plant one swollen seed in the center of a small pot filled with seed-starting mix. Cover it with only a thin layer of mix or vermiculite, about as deep as the seed is thick.

Keep Them Warm

Place the pots somewhere warm and bright. In winter, when days are short, a grow light helps. Keep the soil lightly moist but never soggy.

Be patient. Seeds usually sprout within one to three weeks. Once they come up, keep the seedlings in bright light so they grow sturdy instead of tall and weak.

Transplant the Seedlings

When a seedling has a few sets of true leaves, move it carefully into a bigger pot, about 6 inches across. Try not to disturb the roots too much, because acacias dislike being moved. Once the young plant is strong and the weather is warm, it can be planted outside in a sunny spot if your climate is mild enough.

All About the Acacia Flower

Photo by: Forest & Kim Starr

Acacia flowers are loved around the world for their bright color and sweet scent. They attract bees and other insects, and many birds feed on acacia seeds. Cut stems of mimosa look wonderful in winter bouquets, but they dry out quickly, so put them in water as soon as possible. Whether you grow one in your garden or simply admire them in a vase, acacias bring a burst of sunshine to the coldest months.

Acacia FAQs

Related: tree of life