Feel free to remove the spent flower heads. They don't do the plants any good, and most people think the plants look neater without them. Indeed, the seed pods formed after flowering are a waste of effort on the part of the agapanthus plants.
Although agapanthus are the ultimate easy-case plant, you should take care to remove the finished flower heads. These are quick to seed and can often become a menace in suburbs adjoining bushland areas.
If the weather is turning cold you can collect seed prematurely and store the whole seedhead in a paper bag, but it's preferable to let the seed ripen on the plant. They are easy to grow, preferably sown fresh and pricked out individually next spring. With a bit of luck they should come to flower the following season.
Once you have removed the agapanthus seed pods from the plant, place them in a paper bag and store them in a dry location until the pods split open. Remove the seeds from the split pods. Place the seeds in a sealed container and store them in a cool, dry place until spring.
Without deadheading, the plant goes to seed and the blooming season is shortened considerably. To deadhead agapanthus, simply use pruners or garden shears to remove the faded flower and the stalk at the base of the plant.
Because agapanthus plants spread quickly, they are regarded as an invasive weed in parts of New South Wales and Victoria. Your local council can provide guidance on growing agapanthus, which may include dead-heading flowers before seed dispersal.
NOTE: PeeGee and most other hydrangeas dry best if picked just as they're starting to turn pink. Seed heads from Black Eyed Susans, coneflowers, agapanthus, cattails, lunaria (money plant), iris, teasel, poppies, and Queen Anne's lace are also attractive in dried flower bouquets, as are stems from ornamental grasses.
This plant can be easily propagated through division in late autumn to winter by carefully removing it from the ground or the pot. Gently shake off some of the soil so that you can see the roots and the individual plants. Carefully pull the individual plants apart making sure that each one retains its own roots.
The best time of year to cut back agapanthus is in early spring. Leaving the spent foliage over the winter can protect the crown from rot during winter rains and insulate the roots from cold temperatures. During the summer, you can help the plant conserve energy by removing spent flowers.
Agapanthus is propagated in two ways — by seed or by division of the clump. Once established, agapanthus can spread slowly by seed. Unlike berry-producing weedy plants, such as privet or cotoneaster, agapanthus is not spread by birds. Instead, seeds fall around the clump and have a tendency to drift downhill.
Once you have decided which flowers need to be removed, simply take a sharp, sterilized pair of secateurs and cut off the flowering stalk close to the base of the plant. It does not really matter where on each stalk you choose to make your cut.
Dividing and transplanting agapanthus
However, if left untouched for any length of time, they will become overcrowded and may flower poorly. Lifting and dividing agapanthus every 3 to 4 years will promote better flowering.
Powdery Mildew
As with many other plants, agapanthus that is grown in shady spots may contract powdery mildew, known for the white, powdery coating it causes on the leaves.
Planting into the wrong soil: Seeds need consistent moisture to germinate, but the soil should never be wet or soggy. If the soil is too wet, seeds can rot and disappear. Therefore, use a fast-draining seed starting mixture that allows water to move through quickly.
“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.
Avoid fertilizing your Agapanthus plants with high nitrogen fertilizers - use instead a balanced fertilizer such as 10-10-10 or 5-5-5, or slightly higher in phosphorus than nitrogen. Suspend any fertilizer to either potted or in-ground plants by late summer.
Give agapanthus lots of sun, plus extra water when its really hot and dry and they'll bloom abundantly. Agapanthus plants that fail to flower are usually growing in too much shade.
It is a perennial plant that can live for up to 75 years. Its evergreen leaves are 2 cm wide and 50 cm long. Its inflorescence is an umbel. The flowers are blue, purple or white and bloom from late spring to summer, followed by capsules filled with black seeds.
Repeat flowering Agapanthus for up to 6 months of the year.
Our Agapanthus varieties are designed to be tough enough to brave the Australian landscape, with good disease resistance, and drought and frost tolerance.
You may need to use two garden forks back to back to divide very established clumps. This can be done in spring or after flowering in autumn. Agapanthus species can be grown from collected seed but the cultivars will not come true to type.