Why Are Agapanthus Plants Weed? How to Control African Lilies?

The Lily of the Nile or Agapanthus is an appealing flowering plant that fills space in the garden while adding color. But can Agapanthus be considered a Weed as well?

Agapanthus plants are weeds when they start to spread too much. Desirable conditions and the high tolerance to poor conditions make agapanthus a weed in climates that are hot. 

Is Agapanthus A Weed?

The agapanthus or Lily of the Nile asserts itself as a weed in hot climates!

The Agapanthus has particularly flourished in New Zealand and Australia, to the point that it has become a pest.

They have also inhabited other areas of the world that have a similar climate to South Africa, such as Ethiopia, Mexico, and Mozambique, to name a few. 

The same is possible in states in the USA that have hot climates such as that present in Southern Africa. This includes states that come under USDA Zones 8 to 11. 

No color in the garden? Here are the reasons why agapanthus is not flowering

What Does Agapanthus Look Like?

Agapanthus plants form clumps of light green leaves that are long with the approximate thickness of a belt. 

During summer agapanthus sends up a very long stem that bears a flower bud. Each flower bud encloses a cluster of small flowers that open into a circular arrangement.

When in full bloom, the flower appears as a ball of individual blue, purple, or white flowers.

Depending on age and conditions, the agapanthus could have several clumps of plants and a healthy large bloom of flowers. 

The Agapanthus plant can live for a long time. 

Why Do Agapanthus Leaves Turn Yellow? Tips to Fix

What Makes Agapanthus A Weed?

The Agapanthus has been found to exist and adapt to a variety of different environments. It has endured conditions other plants might find challenging to survive in. They are both tough and drought-resistant. 

Characteristics like this can make any plant appear suspiciously weed-like!

Agapanthus spreads far and wide, in gardens, pots, or even in the wild, making it a weed in the right conditions. 

How Does Agapanthus Spread?

The agapanthus plant does have quite a few methods of spreading. This makes sense seeing as it is considered a weed in more than a few parts of the world. 

#1) Agapanthus Spreading by Seed

After the Agapanthus is through flowering, the flowers die, only to be replaced by seeds, black and paper-like. The seeds cover the distance with wind and then germinate.  

A single flower cluster can contain a lot of seeds! You could say they make more seeds than most other flowers.

#2) Agapanthus Spreading by Rhizomes

After seed dispersal the mother plant does not leave things there, the Agapanthus also spreads underground via rhizomes. 

If you have ever grown ginger you will be familiar with rhizomes. If not, you can picture them as underground shoots arising from bulbs. These rhizomes move and grow horizontally which increases their reach and space occupation. 

#3) Purposely Planting Agapanthus Leading to Spreading

Humans too aid the spreading of the agapanthus species without knowing its full capabilities to spread on its own! 

Unknowingly we pass them to our neighbors, dump them at trash sites and incorrectly dispose of roots and seeds.

Many people even use them to beautify homes and they are part of decorating events. Plus many people grow and sell them commercially for plant nurseries.  

Seeing as it can be invasive, where should you plant agapanthus?  

In What Habitat Does Agapanthus Spread Fastest?

Agapanthus tolerate a wide range of habitats, which makes them fast-spreading and well, a pest! But, what is the most desirable habitat and the conditions that make agapanthus manifest as a weed? 

The areas where you’ll find agapanthus are:

  • Coastal areas 
  • Forests 
  • Open shrub-land 
  • Places of poor soil quality (in the garden) 

Weed-like agapanthus is most dangerous in these areas since most other plants find these areas inadequate to support their growth and multiplication. 

Why Is the Spread of Agapanthus Bad?

Agapanthus will compete with plants for nutrients and water. They are generally hardier and spread readily. In most cases, they beat the competition.

This becomes a big problem when the competition is indigenous plant species. Agapanthus spreads and kills off the indigenous species of the area, and disrupts the local biodiversity. This creates imbalance and loss of native plant species. 

This invasiveness of agapanthus takes over large swathes of land. All at the expense of the local ferns, grasses and other plants that are more delicate and that cannot adapt. At least not fast enough! 

How to Stop The Spreading of Agapanthus?

There are ways of stalling or preventing your agapanthus from taking over your garden.

There is a manual way, which involves doing it yourself using a tactic or technique. Or if you are unsure about that you can try the chemical technique using ready-made products.  

Manual Techniques

Here firstly you can start by cutting the flower stalk as soon as it has finished flower so that it cannot disperse seeds.

Secondly, you can cut the entire plant out, including the stalks, rhizomes, and roots. Dry them thoroughly before throwing them into the trash can, or compost heap.

Chemical Products

If you want to go the chemical way, cut the plant down and apply the weedicide. 

This usually involves treating the stump with a gel/solution to kill off the base and rhizome. You could also just find a weed killer, a spray that would kill off the plant. You would most probably have to apply it to the stumps several times. 

How Effective Are Chemicals Against Agapanthus Weeds?

Weed killing chemicals are growth inhibitors that have a concentrated composition that works well for agapanthus weed plants.

However, they may be slightly slow and they take a few applications to actually get the job done! 

With high chances of seeds falling loose and root matter regrowing, chemicals offer higher success rates than manual methods of managing agapanthus plants. 


When presented with the right conditions the Lily of the Nile will take the opportunity to spread and overtake the area available to it and more. This is why agapanthus is a weed in many parts of the world.

To prevent agapanthus from spreading, you can use manual methods or chemical methods. Manual methods involve pulling out the plant’s bulbs or cutting off flowers before it dries and seeds disperse. 

If you’re growing dahlias, you may read the Reasons for Dahlia leaf curling.


Can I cut the roots of Agapanthus?

No, directly cutting agapanthus roots is not a good idea. If you want to remove the entire plant you must dig your shovel at the end of the root ball. Place it deep enough and then shovel out the roots so that the roots with the plant turn out. 

What does it mean when Agapanthus roots are above ground? 

When the majority of agapanthus roots are above ground it usually means the plant is getting too large and invasive. Hence it shows that it’s time to divide the plant and replant the younger plants elsewhere.