Their elegant spires and vivid blooms make delphiniums a favourite in garden borders. While their first flush of flowers often begins to fade by June or July, a little timely pruning can encourage these cottage garden classics to bloom again later in the season.
Delphiniums are said to be among King Charles's favourite flowers, and it's easy to see why. Their striking blue, purple and white blooms add height, exceptionally vibrant colour and a whole lot of drama to borders, which makes it all the more disappointing when their flowers inevitably fade – but it doesn't have to be so.
Cut them back now, and the show will go on.
'Delphiniums can sometimes have a short flowering season,' says Richard Barker, horticultural expert and commercial director at LBS Horticulture. 'But cutting the flower spikes back once they have faded can encourage the plant to produce a smaller, second flush of flowers around August or September.'
As soon as the spikes begin to wilt, it's time to reach for your secateurs and get ready for a rigorous pruning session.
'Cut every flowered stem back down to the ground,' the expert says. 'Leave any developing side shoots and the remaining foliage at the base of the plant untouched, and water well. Once the plant has finished flowering again for the second time, it can be cut down to the ground.'
How to deadhead delphiniums
- Using clean, sharp secateurs, cut back the main flower spike once the blooms have faded and fallen, taking care to leave any side shoots with developing buds intact
- If an entire flower spike has finished blooming, cut it back to the nearest healthy set of leaves. This prevents the plant from putting energy into seed production and instead encourages strong growth for next year's display
- Once you've deadheaded, apply a general-purpose fertiliser around the base of the plant for an extra boost. Gently work it into the soil and water thoroughly to encourage a second flush of flowers later in the season
If you'd rather increase the number of delphiniums in your garden, allow some flowers to self-seed instead.
'To harvest seeds from delphiniums, wait until the flower petals have fallen and the seed pods are turning brown or beginning to split open. Cut the entire flower stalk, and place it inside a paper bag. Shake the bag to release the seeds from the pods, and store them in an airtight container in the fridge until you are ready to plant,' Richard advises.
Whether you deadhead for a second flush this year or collect seeds for future displays, the delphiniums reward a little extra attention with plenty of gardening enjoyment.
Follow House Beautiful on Instagram, TikTok and Pinterest
The Garden Edit
Folding Bistro Set, 3 Pieces
