Growing Agapanthus In Pots: Restricting The Roots ‘A Myth’ Insists 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.
Contributions From PATRICK FAIRWEATHER
Patrick is the MD of Fairweather’s Nursery, which is home to a Plant Heritage National Collection of Agapanthus. Their Allium cultivar won the HTA Plant Of The Year Award in 2021 and came 2nd in the same category at the Chelsea Flower Show in the same year. Patrick is also the Chair of the RHS Agapanthus AGM trials.
IN THIS GUIDE
Agapanthus, also known as the African Lily, is a herbaceous perennial plant, prized for its attractive flowers which come in a range of blueish-purple hues, or in white.
Though this plant comes from South Africa, and loves sunshine and warmth, it can be grown outdoors in the UK with winter protection and an appropriate location and care.
Can You Grow Agapanthus In Pots?
Agapanthus can be grown in pots or other containers.
Indeed, this is a popular choice for UK gardeners, since it makes it easier for the plants to be moved to an undercover location in winter.
There are deciduous and evergreen Agapanthus.
The deciduous type tend to be somewhat hardier, and some can cope with remaining outdoors year-round in a sheltered spot in more southern or coastal regions.
Evergreen types (and even hardier types in chillier and more northerly gardens) are almost always grown in containers so that they can be moved into an unheated greenhouse or other protected location over the winter months.
Choosing A Container
Individual Agapanthus plants are often grown as pot-grown plants over the summer months.
But you may also decide to grow Agapanthus from bulbs, which are best planted in around April, after the last frost date in your area.
Single plants will usually be grown in a container which is around 20cm in diameter.
If your plant came in a pot, do not be too quick to repot it into a larger container than the one in which it came.
Restricting The Roots
“Experts are split on whether you should restrict the roots of Agapanthus,” shares Horticultural Instructor Dan Ori.
“My personal assessment is along with adding iron nails to the soil for iron and eggshells for calcium, Agapanthus doing well when you restrict the roots is a myth!
The advice to restrict roots is still widely given by many top garden websites, but scientific understanding is always progressing and I would urge you not to let them become pot-bound.
“In fact, living in a pot with little access to nutrients or water is likely to reduce flowering and plant health over time.”
The exact size of the container you should choose will of course depend on the specific variety, and the age and size of a plant (or plants) you have selected.
If you have purchased several smaller plants, these can be placed snugly into a larger container – as long as the root systems fit into the container, they should be happy in the restricted space.
Pots should be deep enough to allow the root systems to sit around 5cm below the surface of the growing medium, and so that there is around 5cm at the top, above the surface of the medium, where water can pool and soak in, and not run off.
In terms of materials, a terracotta pot can be ideal.
The colour complements the blooms of these plants and the porous material can make for good, free-draining growing conditions.
Make sure the container you choose also allows water to drain freely from the base.
Choosing Compost
The ideal growing medium for Agapanthus is a peat-free, loam-based compost or potting mix, such as John Innes number 2 or 3 (or a homemade equivalent) with grit or coarse sand mixed in to improve drainage.
Place your plant or plants into your chosen container, and fill in your chosen potting mix around the roots, taking care not to leave any air pockets.
Water well upon planting, then consider adding a decorative mulch across the top of the container to aid in moisture retention and keep things looking neat and attractive.
Potting Up Agapanthus
Remember, Agapanthus likes to have restricted roots, especially while young.
Your plants will not need to be repotted for the first couple of years at least.
After this, it may be beneficial to repot your plant or plants into slightly larger containers.
How Many Can You Plant Per Pot?
You can plant as many Agapanthus plants into a container as will comfortably fit without damage to the existing root systems.
The plants can sit snugly together without ‘complaint’ and should thrive even if things seem crowded.
If growing from bulbs, these should be spaced approximately their own width apart from one another, at least 5cm below the surface of the growing medium.
Caring For Agapanthus Plants In Containers
- Place an Agapanthus in a container in a sunny, warm and sheltered spot.
- Water container grown Agapanthus a couple of times a week over the summer months.
- Feed the plants with a potassium-rich organic liquid plant feed (such as comfrey tea) every week or so during spring and summer for good flower development.
- Deadhead flowers after a spectacular display over the summer.
- Prune out any damaged or dead foliage in autumn.
- For deciduous types (not evergreens), cut back stems to around 10cm above the ground at the end of autumn.
- Move the container to a frost-free location such as an unheated greenhouse over the winter. (But do not move it anywhere too warm, as this can lead to poor growth and flowering the following year.)
