Look Out For These 7 Problems When Growing Agapanthus Says Dan Ori
Elizabeth is a Permaculture Garden Designer, Sustainability Consultant and Professional Writer, working as an advocate for positive change. She graduated from the University of St. Andrews with an MA in English and Philosophy and obtained a Diploma in Applied Permaculture Design from the Permaculture Association.
Reviewed By DAN ORI
Dan has over 27 years’ under his belt caring for plants and gardens. Working as a Horticultural Instructor and Consultant, he draws on a diverse range of experience that includes working as a Head Gardener, Tree Surgeon, Garden Centre Trouble Shooter, and writer of academic papers. Dan has a Level 3 Diploma in Horticulture and is currently a candidate for the RHS’s most prestigious award – The Master of Horticulture.
IN THIS GUIDE
Agapanthus are popular flowers.
While native to South Africa, these plants can cope with British conditions as long as you take care of them, especially over the winter.
But while they can often do very well in our gardens, there are certain problems to look out for.
1) My Agapanthus Won’t Flower
The most common issues gardeners experience when growing Agapanthus relate to flowering.
Agapanthus can flower fairly reliably when cared for correctly. However, they can flower poorly, or fail to flower at all.
A problem with flowering is usually due to one of the following issues:
- Too much shade
- Too little water or too much
- The wrong sized container
- Low fertility (especially when grown in pots)
- Incorrect winter care and protection
- Agapanthus gall midge
- Plant diseases
Of course, in addition to causing poor or non-flowering, these issues can also cause other symptoms in Agapanthus plants.
Read on to explore each one of these issues in a little more depth.
2) Sunlight Issues
Most issues with Agapanthus non-flowering relate to some problem with the environmental conditions.
One such common issue is a lack of sunlight.
Remember, Agapanthus need a spot that is as sunny as possible.
Too much shade is one reason why your plant may not be flowering as well as it should.
3) Watering Issues
If the weather has been very dry, and especially when growing in containers, a lack of watering over the previous spring, summer and early autumn may be to blame for poor flowering.
Once established, these plants can be relatively drought-tolerant.
But still have to be watered frequently when growing in pots, and certainly until they are well settled in.
However, Agapanthus also needs well-drained conditions.
Waterlogging, and excessive watering, can also cause issues.
Roots may rot (and fungal diseases, see below, may be more likely to set in) when conditions are too damp.
4) Agapanthus Fertility Issues
Agapanthus, especially when grown in containers, can also suffer from a lack of fertility.
Low potassium, for example, may reduce flowering, or even mean that a plant does not flower altogether.
It is a good idea to feed your plant with a potassium-rich liquid feed from spring through to early autumn.
Fertility issues may also cause other symptoms, such as yellowing leaves, in certain cases.
5) Issues With Agapanthus Winter Care
Another common issue with Agapanthus is incorrect winter care.
Hardier Agapanthus can often overwinter outdoors, but usually need some protection – such as a mulch of straw or autumn leaves piled over the crown.
In more northerly gardens, and for more tender cultivars, it will usually be necessary to move plants to an unheated greenhouse or other protected frost-free location over the winter months.
Where this is not done, plants will be damaged, and can die.
Exposure to cold can also reduce flowering the following year, even when plants do survive the winter.
However, poor quality flowering can also be due to being kept in too warm a location over the winter months.
Agapanthus spaced in heated conditions over winter may flower earlier, but the flowers will usually be inferior in this case.
6) Gall Midge
If the flower buds on an Agapanthus become discoloured and deformed and don’t open, this can be due to Agapanthus gall midge.
This is caused by the larvae of a small fly, Enigmadiplosis agapanthi, first observed in the UK in 2014.1Agapanthus gall midge. (n.d.). Royal Horticultural Society. Retrieved March 9, 2023, from https://www.rhs.org.uk/biodiversity/agapanthus-gall-midge
When the deformed buds are opened, little maggots can be seen inside.
The affected flower heads should be carefully removed and destroyed.
7) Plant Diseases
While Agapanthus are not usually troubled by disease, there are several fungal issues that can occur – such as Anthracnose, powdery mildew, grey mould, and root rot, for example.
Ensuring that you have provided the right environmental conditions for your Agapanthus, and are not causing problems through your watering, can help reduce the chances of such problems taking hold.
