What to do with agapanthus after flowering – 3 steps to help you lengthen your plant's life

A huge number of plants are set to finish blooming over the coming months, and soon, it’ll be time to figure out what to do with agapanthus after flowering.

Of course, there's the question of whether or not you should deadhead agapanthus, but it can be tricky to know which steps to take after your plants have totally stopped flowering for the year. Cut them back? Leave them be?

As it turns out, the type of agapanthus you’re growing will determine what you should do with it after it’s finished flowering. Deciduous agapanthus is more common, but there are evergreen species, too.

Below, you’ll find everything you need to know about looking after agapanthus, deciduous or otherwise, in September and October.

1. Deadhead

If you’re wondering what to do with agapanthus after flowering, deadheading is one of the earlier steps – and late summer and early autumn are often the best times to deadhead agapanthus. A sharp pair of garden snips, like the Kent & Stowe Eversharp Garden Snips, now £15.99 at Amazon, can make the task smooth and enjoyable. It's worth investing in a pair of garden gloves, too, because agapanthus is toxic.

‘Make sure you deadhead the faded flowers by snipping off any spent areas above the next set of healthy leaves,’ advises Elise Harlock, flower expert at Prestige Flowers. ‘This not only tidies up the plant but also prevents it from putting energy into seed production, which can result in fewer flowers appearing in the future.’

If you’re a fan of the way the seedheads look, you don’t have to deadhead them straight away.

'The definite rule is to deadhead agapanthus promptly after flowering, but I prefer to hold off on this slightly as I quite like the architectural look of the seedheads,’ says David Glass, head gardener at Bowood House and Gardens. ‘If the seedhead stems are still standing up and looking healthy, it's fine to leave them for a little while longer.

‘At the very latest, I tend to deadhead agapanthus in late summer or early autumn before they start to actually seed.’

2. Cut the plants back

There are some plants you should never prune in autumn, but agapanthus isn’t one of them – in fact, cutting them back is key to conserving their energy for next year. You'll just need a pair of secateurs like the WOLF-Garten Bypass Secateurs, which are £24.99 at Amazon.

You’ll need to make sure you’re growing a deciduous variety first, though, and always wait until the foliage has yellowed and started to die back naturally.

‘Cut back deciduous agapanthus to ground level in autumn after flowering,’ says David.

Until the foliage has died back, a little extra TLC can go a long way to boosting your plants’ health.

‘Continue watering your plant regularly while the foliage is still green, and remember to feed it with fertiliser every few weeks to build up strength for next year,’ advises Elise.

You don't need to cut back evergreen species, though. 'If you have evergreen agapanthus in the garden, you should leave the foliage alone, as evergreen agapanthus remains green all winter long,' David explains.

3. Consider dividing overgrown plants

If you know how to divide perennials, you’ve already got a valuable skill up your sleeve – and early autumn, when it's finished flowering, is the ideal time to divide agapanthus, especially if your plants are looking particularly root-bound.

‘If you’re growing agapanthus in a pot, autumn is a good time of year to check whether it’s become overcrowded,’ says Elise.

‘They actually like to be a bit pot-bound, but if you notice roots circling the base or the soil drying out too quickly, consider dividing the plant to give it more space to grow.’

A garden knife like the Spear & Jackson Razorsharp Hori Hori Multi-Tool, £19.95 at Amazon, can make this task easier.

FAQs

Should agapanthus seedheads be removed?

Some annual flowers don't need deadheading, and actually, leaving the seedheads on the plant can benefit wildlife - but perennial agapanthus can, and should, be deadhead.

'Agapanthus seedheads should be removed to stop the self-seeding process,' explains Bowood's head gardener, David. 'If the seedheads are left on the plant for too long, it causes weed agapanthus to form, which becomes invasive in some soils. The weeds are very difficult to manage and can disrupt the garden.'

Agapanthus is one of the best drought-tolerant plants for pots and borders, and knowing what to do with the plants after flowering will encourage the blooms to bounce back every year.