With tall stems and dramatic blue blooms, agapanthus has the magic ability to make a garden look instantly more impressive. But once those flowers fade, what kind of post-bloom TLC should you actually give your plant?
We asked gardening expert Lucie Bradley from Easy Garden Irrigation for her best tips on what to do for agapanthus after flowering.
Should you deadhead agapanthus after flowering?
Some gardeners leave the flower heads in place so the plant can produce seeds for wild birds. However, birds tend to favour coneflower and globe thistle seeds over agapanthus.
"I tend to encourage my plants to preserve their energy from producing seeds and instead direct it all back into their foliage and roots," says Lucie. "Which should result in a strong, healthy plant when it comes time to produce new blooms next year."
Deadheading keeps agapanthus looking neat and prevents self-seeding. It also removes spent flower heads, which can develop grey mould as they decay.
"It's extremely uncommon that deadheading your agapanthus will encourage further flowers," says Lucie. "You may get an odd, rogue stem appear, but it's so unlikely that this isn't the reason you deadhead the faded flower heads".
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This allows the plant to direct its energy back into its foliage and roots, ready for next year's blooms.
How should you water agapanthus after flowering?
Agapanthus are well suited to gardens currently coping with repeated heatwaves. They thrive in hot, dry weather, with their tuber-like roots helping them produce vibrant blooms. These "act like sponges to soak up moisture and nutrients and release it back to the plant, so it's very drought-tolerant," says Lucie.
Thanks to their drought tolerance, agapanthus in beds or borders only need deep watering once or twice a week during dry spells, says Lucie. Plants in containers, however, will need watering more often as they dry out faster.
Even after flowering, continue to water deeply during dry spells. If you've deadheaded, cut the flower stems away at the base but leave the green leaves in place. This helps the tuberous roots and rhizomes store "nutrients and water", helping the plant survive winter dormancy and fuel "healthy, new growth in spring".
Should you feed agapanthus after flowering?
Feed from early spring to fuel new growth, using a high-potassium feed to encourage blooms. Once the flowers have faded, however, it's time to stop feeding. Lucie warns that doing so "will stimulate new growth which could potentially be damaged by the colder weather in autumn".
Instead, she recommends giving plants "a last feed in late summer (August usually)," still using a high-potassium formula. This replaces nutrients lost during flowering. It also supports the roots and helps the plant produce strong blooms next year.
What should you do with agapanthus leaves after flowering?
One key thing to remember in late summer is to leave the foliage in place when you deadhead. The leaves keep feeding the plant, storing energy in the roots for next year's blooms.
Let the leaves die back naturally, says Lucie, and only cut "once they have turned brown and completely dried out". After that, add a layer of mulch over the crown to help protect it from frost over the winter months.
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