Deciduous Agapanthus Are Usually Cut Back Hard In Late Autumn – Experts Share How
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 COLIN SKELLY
Colin is a Horticulturist and Horticultural Consultant with experience in a range of practical and managerial roles across heritage, commercial and public horticulture. He holds the Royal Horticultural Society’s Master of Horticulture award and has a particular interest in horticultural ecology and naturalistic planting for habitat and climate resilience.
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 are tender perennials that need protection over the winter months but can be grown in many UK gardens.
They are often grown in containers so they can easily be moved undercover for the coldest months, though they can also be grown in a border in southern, warm, sunny and protected gardens.
If you are growing Agapanthus, you might wonder if you should prune your plants. And, if you do, when and how you should do so.
Here’s the usual process to follow:
- Determine whether you need to prune at all by determining if you have a deciduous or evergreen type.
- Decide whether you will cut back deciduous Agapanthus in autumn or spring.
- Cut back deciduous Agapanthus to around 10cm above the soil surface
- Leave evergreen Agapanthus alone, or give it a trim for aesthetic reasons if you wish.
When To Prune Agapanthus
Agapanthus of the types which are pruned are usually pruned or cut back in October, or in March.
Whether you prune in autumn or spring will largely depend on personal preference.
Do You Need To Cut Back Agapanthus?
Whether or not you should prune Agapanthus at all depends on whether you are growing a deciduous or evergreen type.
Deciduous types are usually cut back hard, but evergreen types are usually left alone, unless you wish to give them a little tidy up for aesthetic reasons.
Identifying Your Type
Deciduous Agapanthus are those which die back over winter; evergreens will keep their foliage year-round.
Deciduous Agapanthus tend to be hardier than the evergreen types.
Deciduous types are sometimes overwintered outdoors with a thick mulch of straw or autumn leaves to protect the crown, while evergreen types are almost invariably moved undercover for the winter months.
Pruning Deciduous Agapanthus
If you have a deciduous Agapanthus that you plan to keep outdoors over the winter months, then it is usual to cut back the stalks with spent flowers or seed heads (if these have not already been deadheaded) to around 10cm above the ground.
However, I sometimes choose to leave seed heads in place, since these can be rather attractive, and only cut the plant back to the base in spring.
However, you may choose to leave the foliage in place to offer a little extra protection for the crown over the coldest months before you cut back straggly old leaves in the early spring to make way for new growth.
“I remove the foliage of deciduous Agapanthus in late autumn as I find that it rots quite quickly to a slimy mess,” says RHS Master Horticulturist Colin Skelly.
“Unless you are in the very coldest regions in the UK these Agapanthus should be perfectly hardy without additional protection.”
If growing in a container and moving under cover over the winter, you may choose to cut the plants right back down to the crown in Autumn (as shown above).
“Agapanthus stems can be pruned at ground level when the flower has gone over unless you want to leave them in the garden for winter structure,” says Patrick Fairweather, the Managing Director of Fairweather’s Nursery.
“Flower stems should also be removed from young plants to encourage root and shoot development.”
Provided you overwinter adequately you will see new shoots of growth in the following Spring.
I covered the plant shown in the images above with a layer of mulch and it survived the winter outdoors next to our garden wall.
Pruning Evergreen Agapanthus
Evergreen Agapanthus should usually not be pruned or cut back.
It should be left alone, aside from removing any unsightly leaves or removing particular portions of the plant with a little trim to improve its visual appearance.
“I enjoy the foliage of evergreen Agapanthus in the winter when most other perennials have died back,” admits Colin.
“I leave the dead flower stems in place for attractive early winter structure but remove these as winter progresses and the stems begin to degrade.”
