Agapanthus is the flower of summer and its tall blue, mauve or white heads grace gardens across Sydney. Agapanthus (Agapanthus praecox subsp. orientalis) is a perennial from South Africa and it’s a survivor from its thick, fleshy roots to its luxuriant green strappy leaves.

It is a top choice to plant as a fire retardant plant. Although these plants burn in a fire, they can help slow its progress and recover quickly after a blaze. To use them as a firebreak, plant them thickly without organic mulch. Use them as a border to mown grass or under deciduous trees. The thick roots also bind soil and reduce erosion.

Growing agapanthus

Give agapanthus lots of sun, extra water when its really hot and dry and they’ll bloom abundantly. Agapanthus plants that fail to flower are usually growing in too much shade.

While they grow with little care, agapanthus plants respond to an application of fertiliser or composted manure in spring.

Despite loving sun exposure, agapanthus plants are susceptible to heat damage in extreme summer temperatures, especially where heatwaves push temperatures over 45°C. They are more likely to be burnt by heat when the plants are already drought stressed or if they are growing in a hot spot such as against a metal fence or wall or beside a hot path or driveway. Although leaves and flowers are damaged in high temperatures, they recover sending out new growth when conditions improve. Remove damaged leaves and flowers to improve the appearance of the clump.

Designer ideas

The flowers are bird attracting and long lasting. They can be picked to use in a vase indoors.

Agapanthus can be used to tie a garden together. They lend themselves to mass planting as a border. Who hasn’t seen a row of agapanthus along a driveway or edging a garden or pool fence and not admired them?

As these plants put on their best flower show in summer they also make a smart choice for planting around outdoor entertaining areas such as patios and swimming pools.

Smaller varieties can be used to form a strappy contrast to more formal clipped hedges. Use a row of dwarf white or blue agapanthus in front of stepped hedges of gardenia, murraya or lillypilly.

Avoiding weediness

Agapanthus grows by seed or by division of the clump and both can lead to weediness. Where weeds have spread it is usually due to the dumping of unwanted plants into bushland areas. Once established, agapanthus spread slowly by seed. Seeds are not spread by birds but fall around the clump and may drift down hill. To restrict the spread of these plants from your garden, remove the stalks as flowers finish and don’t dump unwanted plants where they can spread.

Removing a mass of agapanthus stalks sounds like an onerous task, particularly for a plant that’s often selected for its low maintenance, but with sharp secateurs and wheelie bin or other container, it’s a job that doesn’t take long. Cut at the base of the stem. The stems can be chopped up and added to the compost or used as mulch. If more plants are desired around the existing clump and weediness is not a problem, leave some of the seeds to mature and grow.

As well as removing the spent heads to stop weediness, removing spent flower stalks also tidies the clump, returning agapanthus to their neat and orderly appearance.

Pest problems

Clumps may harbour snails or slugs. Occasionally, foliage is attacked in summer or autumn by lily caterpillars. Squash caterpillars or apply an insecticide to control caterpillars.

Plants that are stressed (for example by growing in too much shade or by dry conditions), can be attacked by mealy bugs. Mealy bugs are hard to control as they colonise the roots as well as inside the foliage. Apply a registered pesticide or remove plants.