How to Propagate Dietes (Clumping Iris Grass) Easily – Division vs Seeds

In this video, I show how to propagate Dietes grandiflora (African Iris or Fortnight Lily).

This simple explanation shows you how to grow iris / dieter varieties or clumping grasses from cuttings, it offers a comparison of soil based, potting mix based and seed and shows the outcome of cuttings after 4 weeks.

Many gardeners ask: Can you grow Dietes from seed? When should you divide iris clumps? How do you stop them from wilting after transplant? This video answers it all.

All cuttings were successful in both potting mix and soil. Iris seedlings average germination is 30-50%.

Note it was grown through Autumn in a subtropical climate and was given around 4 hours sunlight a day.

Note these cuttings were leaf cuttings. Dietes can also be propagated directly from rhizomes.

Tips for propagation

Propagation tips for clumping Dietes (African iris) using leaf‑fan cuttings / rhizome division
Lift and divide after flowering or in early spring while soil is still warm.
Use a sharp, disinfected spade or knife; each section needs one solid rhizome piece and at least one healthy fan.
Trim foliage to about 15 cm (6 in) to reduce transpiration.
Let cut surfaces air‑dry 30‑60 min in shade so they callus and resist rot.
Plant at the same depth the clump was growing in a free‑draining mix enriched with compost and coarse sand.
Water in deeply and keep the root zone consistently moist (never water‑logged) for the first 4–6 weeks.
Provide light shade or a temporary shade cloth if daytime highs exceed 30 °C to limit transplant shock. Iris , Dietes, Clumping Grasses can be propagated in summer and autumn but shade and sufficient moisture are required,
Feed fortnightly with a dilute seaweed or fish‑emulsion tonic until new growth appears, then switch to a balanced slow‑release fertiliser.
Mulch 2–3 cm thick to preserve moisture, but keep mulch a few centimetres clear of the rhizome crown.
Space divisions 40–50 cm apart; this gives each plant two seasons to fill in without overcrowding.
Pinch off any flower spikes in the first season so energy goes into root establishment.
Seed propagation is possible but much slower (18–24 months to first flower); stick with cuttings/division for quick results.