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 do 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, plus 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.
Agapanthus are most commonly seen in shades of blue and white.
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 lilly pilly.
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.
Agapanthus Zambezi is a new, variegated form that is exclusive to Flower Power.
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.
FAQs
Agapanthus thrives with consistent watering but requires exceptionally well-drained soil to avoid rot. Along with steady water, using an organic, balanced fertilizer keeps plants blooming consistently through summer into early fall. Always follow fertilizer instructions precisely.
When should agapanthus flowers be cut back? ›
Deciduous varieties – Cut back agapanthus stems to about 4 inches (10 cm.) above the ground at the end of the blooming season. However, if you like the texture and structure that spent plants provide to the winter landscape, cutting back agapanthus can wait until early spring.
Will agapanthus bloom all summer? ›
Enjoy Nonstop Blooms All Summer Long
(Most agapanthus bloom only once per season.) The bell-shaped flowers of the two Summer Love varieties in this collection are white and medium blue, and form in somewhat spherical clusters; the foliage of both is deep green and grasslike.
How many times does agapanthus bloom? ›
With proper care, agapanthus flowering occurs repeatedly for several weeks throughout the season, then this perennial powerhouse returns to put on another show the next year. Agapanthus is a nearly indestructible plant and, in fact, most agapanthus varieties self-seed generously and may even become somewhat weedy.
Should I cut the dead flowers off my agapanthus? ›
Agapanthus do well in pots. Cut back spent flowerheads after blooming and mulch annually with well-rotted compost or other organic matter.
Does agapanthus spread? ›
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.
Does agapanthus multiply? ›
Agapanthus does multiply by underground rhizomes which will send up new plants (or by seeding.) These new plants can be separated and transplanted, in fact, thinning and separating every 4 or 5 years will help the plants to remain healthy!
What do I do with agapanthus seed heads? ›
Place the seed in open paper (not polythene) bags until it has dried and then store, now in sealed bags, in a cool, dry place until March or April. Space sow the sound seed on the surface of a gritty compost and cover with a thin layer of grit of more compost.
Do agapanthus flower once? ›
Repeat flowering Agapanthus for up to 6 months of the year.
These gorgeous plants produce masses of bright and colourful flowers in spring and summer, as well as sporadically throughout the year, including in mild winters as seen in 2020.
What is the best fertilizer for agapanthus? ›
Feed twice during the growing season – once in early spring and again two months later. Avoid fertilizing your Agapanthus plants with high nitrogen fertilizers – use instead a balanced fertilizer such as 10-10-10 or 5-5-5, or slightly higher in phosphorus than nitrogen.
It is a perennial plant that can live for up to 75 years. Its evergreen leaves are 2 cm wide and 50 cm long. Its inflorescence is an umbel. The flowers are blue, purple or white and bloom from late spring to summer, followed by capsules filled with black seeds.
Do agapanthus like full sun or shade? ›
Grow Agapanthus in full sun or partial shade (partial shade is recommended in warm inland areas of the West) and rich, well-drained soil. Most plants are tender and should be grown in containers to bring indoors for the winter (except for 'Midknight Blue' which is hardy in Zones 6–10).
How long do agapanthus last? ›
Most Agapanthus bloom for around 6 weeks, however 'Flower of Love' has been specially bred to be much more floriferous than other varieties, for an incredible 10-12 weeks, starting around mid-July. Thick fleshy roots store fluid and nutrients to enable these low-maintenance plants to flourish in poor dry soils.
What makes agapanthus bloom? ›
Grow Agapanthus as a houseplant in bright light and average temperatures. Keep well watered when growing, but allow it to dry out in winter. This plant blooms best when grown in full sun and pot-bound, so don't divide or replant until the plant is pushing out of its pot.
What kills agapanthus? ›
How do you get rid of it?
- Dig out smaller isolated plants. Ensure that the whole rhizome is removed.
- Slash leaves close to the ground and paint the fresh stump with vigilant gel, glyphosate, or metsulfuron-methyl.
- Spray with triclopyr.
Grow Agapanthus in full sun or partial shade (partial shade is recommended in warm inland areas of the West) and rich, well-drained soil. Most plants are tender and should be grown in containers to bring indoors for the winter (except for 'Midknight Blue' which is hardy in Zones 6–10).
