Gardening glossary
Division (propagation)
Division turns one plant into several almost instantly. Unlike cuttings or layering, which create new plants from a piece of stem that has to grow its own roots, division produces fully-rooted plants the same day. The success rate is close to 100% if the species suits the technique.
Plants that divide well share one feature — they grow as a clump of multiple crowns or rhizomes joined at the base. Each crown has its own roots and growing point and can survive independently once separated.
Common candidates for division:
- **Houseplants:** snake plant, ZZ plant, peace lily, calathea, prayer plant, bird's nest fern, spider plant, most aroids that produce pups. - **Perennials:** hostas, daylilies, irises, ornamental grasses, agapanthus, sedums, asters, primroses, hardy geraniums. - **Edibles:** rhubarb, chives, lemongrass, mint (any plant that grows from spreading rhizomes).
When to divide:
- **Spring** is best for most plants — they bounce back fastest when they are about to grow vigorously. - **Autumn** suits early-flowering perennials like irises that have already finished blooming. - **Houseplants** can be divided whenever they have at least two clear crowns and the plant is generally healthy — avoid dividing a stressed or actively flowering plant.
Step-by-step:
1. **Unpot or lift** the parent plant. 2. **Loosen the root ball** with your fingers and shake away enough soil to see the natural separation points. 3. **Separate the clumps.** Often you can tease them apart by hand. For tough roots or rhizomes, use a clean knife, two garden forks back-to-back, or even a sharpened spade for very dense clumps. 4. **Each division needs roots and at least one growing point** (a crown, eye, or bud). Tiny divisions with few roots take longer to establish. 5. **Repot promptly** at the same depth as the parent, water in, and keep slightly shaded for a week while the roots settle.
Division also rejuvenates old clumping plants. A mature hosta or peace lily that has lost its centre and looks doughnut-shaped is telling you it is time. Dividing every 3–5 years keeps the plant young.