If you don't divide agapanthus, the clumps become overcrowded, leading to a loss of vigor, sparse foliage, and most notably, reduced or failed flowering, often with a bare center developing as the plant ages. Over time, the plant puts energy into dense root growth instead of blooms, but dividing it rejuvenates it by giving roots more space and promoting healthier, more abundant flowers, according to a YouTube video and Gardening Know How.
Agapanthus are best divided and transplanted in the fall for spring blooms. Eventually you'll want to tackle large bunches and divide Agapanthus to ensure your lilies continue to produce those lovely blue or white bloom clusters.
It is strongly recommended to never risk the survival of your agapanthus by dividing them in the summer months. Again, only divide agapanthus after flowering. The best time to do this is in autumn.
Lifespan of the Agapanthus
A perennial plant grows more than once during its lifetime and lasts longer than 2 years. These are plants that produce new stems, leaves, and flowers every year. Give your Agapanthus the best care, and you will enjoy it for years to come!
(If you propagate from seed you're unlikely to end up with exactly the same flowers, as the plant may have cross pollinated with other varieties.) The best time to divide agapanthus is late March to April, before the flowering season.
The best time to repot Agapanthus is spring . You can do it later, but the later you do it, the less chance of flowers that year.
Do not plant agapanthus in shady spots or areas with poor drainage, as they need full sun and well-drained soil to flower well and avoid root rot; also avoid planting near bushland or sensitive ecosystems due to their invasive potential, opting for sterile varieties or containers if concerned about spread.
Agapanthus do well in both pots and the ground, with the best choice depending on your goals: pots offer control for limited space, frost protection (by moving indoors), and preventing spread, while the ground allows them to naturalize and form large clumps for a bigger impact, though they need more effort to manage if they become invasive. Pots are great for patios, balconies, and colder climates, while in-ground planting suits sunny garden beds.
This can be done at any time, though it's best to remove dead heads before they go to seed, as soon as the flowers die in spring, summer or early to late autumn. Deadheading keeps the plants from spending energy on producing seeds and helps the plant produce extra blooms.
Bulb rot and root rot are both agapanthus problems that start underground. They show themselves above ground in yellow, wilted leaves and sometimes stunted plants. If you dig the plants up, you'll find the roots or bulb decayed and discolored. If one of your plants is infected with root or bulb rot, it can't be saved.
Agapanthus plants thrive in well-drained soils, preferring full sun but also tolerating partial shade. Their resilience against drought, once established, further enhances their appeal.
Autumn is the perfect time to divide these clump forming plants (and others, like clivia, agapanthus and Dianella), and all that is required is a sharp shovel or spade and some secateurs.
It is possible for Agapanthus to self-seed.
Agapanthus flowers are typically purple, blue or white. Plants with orange flowers (or foliage) like birds of paradise can make the blue blooms of agapanthus stand out. Meanwhile, yellow flowers such as billy buttons can compliment purple agapanthus blooms.
If the tips of the leaves turn brown, you can tidy these up by cutting the ends off – preferably in a 'V' shape so they still look natural. By the Autumn, everything should have turned brown, you can then remove all the foliage that has died and cover your Agapanthus with some mulch for protection against frosts.
Evergreen types are more tender and their leaves can be damaged by frosts so they will need good protection over winter. Evergreen types in pots should be brought undercover over winter. If your agapanthus are in the ground, a mulch of straw or fleece is essential (unless you live in South-West England).
Divide congested clumps of agapanthus every four or five years. Lift the plants and carefully divide the crown with a sharp spade, making sure that each section has at least two growing points.
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.
Agapanthus planting is best performed in the fall or winter in warm climates, and in the spring after the danger of frost has passed in cool climates. The ravishing, spherical flower clusters will arrive in early to mid-summer.
It's generally not illegal to plant Agapanthus in most places, but it's highly discouraged in many regions (especially Australia, parts of the UK/Europe, and California) because it's considered an aggressive, invasive weed that spreads into natural areas, impacting native plants. Laws vary by location, but you'll often find local council bans or strong recommendations not to plant common varieties, encouraging sterile cultivars instead to prevent seed spread into bushland and waterways.
A problem with flowering is usually due to one of the following issues:
Not Enough Light
If your plant is growing lots of healthy foliage but seems reluctant to bloom, too little light is probably the most common issue of all. Plants of all types use day length as a signal to induce flowering.
As agapanthus is one of the best bulbs to plant in February, most agapanthus plants will flower for around six weeks from mid-summer to early autumn. However, you can deadhead them as soon as their colour starts to fade and they start to lose their vibrancy.