Mophead acacia, a beautiful acacia with a happily frazzled appearance

Delineated mophead acacia tree

The mop-head acacia tree is an appealing ornamental tree.

From planting and pruning to basic care, follow our advice to grow a thick, round mophead acacia.

Mop-top tree key facts

NameRobinia pseudoacacia ‘Umbraculifera’

Height – rarely over 20 feet (6 m)
Exposure – Full sun

Care – Little care required
Leafage – deciduous

Soil type – ordinary
Special appeal – Standalone tree in a garden

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Planting a mophead Acacia tree

It is best planted in fall to promote root development.

  • When purchased in containers or nursery pots, plant it in spring, you won’t have any problems.

It’s preferable to select a location that gets lots of sun exposure. Avoid planting too close to a house, or even near any other tree: it’s most striking when grown as a standalone tree.

If you purchased your tree with bare roots or from a container that’s a bit small for the tree’s height, it may be a good idea to stake the tree.

  • Having the trunk perfectly vertical will guarantee that the mophead acacia looks stunning!

Mop-top acacia roots

The root system of this Acacia species is very vigorous. It will send up offshoots and new trees will start growing up to a dozen feet (3 meters) away from the original tree.

Setting up a rhizome barrier will help slow the spread.

Pruning a mophead Acacia tree

It doesn’t need any pruning.

If ever you wish to bring the branches back somewhat, prune and trim during the tree’s dormant season.

  • This is from November to March in the northern hemisphere,
  • and from March to November in the southern one.

Endeavor to keep the nice round shape as you prune.

Good to know: spikes appear on younger branches, so best have thick gloves on when handling the plant.

As for root suckers, simply cut them down to the ground twice a year to keep them from growing too large.

Mophead acacia in container pots

Growing mophead acacia trees in pots

Mophead acacia is an excellent container pot choice. It will do fine as long as it is kept sufficiently watered in well-draining soil.

  • Prune yearly in fall to keep the tree small.
  • This is an excellent option to avoid problems with neighbors because of root suckers.

Repotting mophead acacia in containers

  • Every two years, repot to a slightly larger container until you reach one that is around 18 inches (45 to 50 cm) across.
  • When in the final container, instead of repotting to pots that would be too large and unwieldy, simply topdress with nutrient-rich compost.

Good to know about the Mop-head Acacia tree

Mophead acacia is recommended as a standalone. This highlights its particularly dense and lush green foliage.

The “mop-like” silhouette occurs naturally. It gets so thick that it becomes almost impossible to see through the tree!

The reasonably small size, about 20 to 25 feet (6 to 8 m), makes it a great choice for planting in small-sized gardens. It’s also very appealing when grown alongside roads. Municipalities find that it is an easy tree to care for with easy-to-control growing.

  • Like the other black locust tree varieties, it will produce clusters of flowers of an ivory-white color that will then turn into seed pods.

Mop-top acacia varieties

Weeping mophead acaciaSome varieties of mophead acacia are quite remarkable. This “pendulum” variety looks very similar to that of the Japanese pagoda tree.

Other notable ones are:

  • ‘Frisia’ has golden-yellow leaves
  • ‘Tortuosa’ has twisting corkscrew-like branches
  • ‘Unifoliola’ is shorter and doesn’t have any spikes.

Smart tip about Mophead acacia care

Dense leafage of the mophead treeSpread mulch around the base to make the tree stand out. It will also hinder weed growth and will protect the roots in winter.

Image credits (edits Gaspard Lorthiois):
CC BY 2.0: Wendy Cutler
CC BY-SA 4.0: Athantor