It simply involves lifting a mature existing Agapanthus from the soil, or from its container, and splitting the root system apart to give two or more new plants.
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.
Agapanthus are easy to propagate by division to obtain plants identical to the parent plant, this is best done between spring and early summer. Avoid splitting plants too often as this will reduce flowering. Large clumps in the border should be lifted in spring every 4 - 6 years and replanted.
This will depend on how they're planted. If they're planted in the ground, expect to divide them roughly every 4-5 years. If they're planted in a pot that's smaller than their mature width, expect to divide them about every 2-3 years.
Agapanthus are grown from bare-roots and should be planted in spring. It's best to start them off under cover or in a warm, bright place to give them a good start.
Dividing and transplanting agapanthus
One advantage of growing agapanthus is that once you've got one, you're guaranteed to have more, because they multiply by themselves in clumps. However, if left untouched for any length of time, they will become overcrowded and may flower poorly.
Use a clean pair of pruning shears to remove any spent foliage in early spring before new growth emerges. Remove the entire flower stem as the blooms fade using a sharp pair of pruning shears or scissors.
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.
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.
Agapanthus species are hardy plants, and are easily grown. Although tolerant of drought and poor soil, both flower and foliage production improves with moisture and feeding. They perform best in a position in full sun or part-shade in any well-drained soil.
Although often said, agapanthus don't actually flower better when pot-bound. It's true they like to be cosy in their pot, flowering poorly when overpotted or over-divided, but they are also shy to flower when excessively pot-bound.
RESIDENTS growing agapanthus plants are urged to take to their gardens and remove the seed heads before they open and release their potentially invasive seeds.
Generally 3-4 inches deep for the larger variety and about 2 inches for the dwarf varieties.
Pot-grown agapanthus will benefit from an annual feed – a liquid tomato feed is ideal. Deadhead spent blooms to encourage more to form, or leave the faded flower heads in place if you want to collect the seed. The attractive seedheads are often left on over autumn for decorative reasons.
“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.
growing agapanthus in a pot
Agapanthus perform best where root development is restricted, as restricted roots encourage flower formation. This makes agapanthus well suited to being grown in pots, especially the evergreen types which can then be brought into a conservatory or greenhouse for the winter.
Agapanthus may take two or three years before they begin to flower. For the first growing season, it should be watered regularly and deeply so it can establish a root system. It should be watered whenever the top three inches of soil is dry.
Agapanthus come in a wide variety such as evergreen and deciduous to tall and dwarf. All have a dense fleshy root system that produces arching, strap-like, dark green foliage in a clumping habit. During mid Spring to early Summer tall flower spikes will emerge with round umbels of brightly coloured flowers.
Deciduous varieties – Cut back agapanthus stems to about 4 inches (10 cm.) above the ground at the end of the blooming season. However, if you like the texture and structure that spent plants provide to the winter landscape, cutting back agapanthus can wait until early spring.
Dividing agapanthus
Lift the plant out of the ground and split the root clump with a sharp spade or two forks back-to-back, making sure each of the new clumps has at least two growing points. Then simply plant these out as usual. Most agapanthus plants benefit from dividing every 3-5 years.