UNITED STATES—Propagation produces more plants from minimal and readily available resources. Within home gardens, propagation is practical by seed, cutting, layering or division. Seed which is not available directly from the garden is generally not very expensive. Cutting, layering and division utilize what already lives within the garden. In other words, the stock is free.
Seeding produces genuinely new plants. Other forms of propagation produce genetically identical copies of their parent plants. Cutting compels pieces of stem to grow new roots. Layering does the same, but while pieces of stem remain attached to their parent plants. Division involves separation of portions of stems that already developed their own roots.
Most species that are conducive to division are substantial perennials. Flowering quince and lilac, though, are woody shrubs that produce dividable suckers. Most division should happen during late summer or early autumn. However, several species prefer late winter. Deciduous species, like lilac and flowering quince, prefer it during their winter dormancy.
Every species is on its own schedule.
Shasta daisy, Lily of the Nile, daylily and coneflower prefer division during late summer. It is after their bloom and summer warmth, but before cool weather of winter. They disperse their roots through winter to resume growth even before spring. Bearded iris are ready for division a bit earlier and resume growth by autumn. They are then ready for early spring.
Division of phlox and penstemon should be a bit later, when they get cut back. Bergenia blooms for winter, so should not be disturbed until late winter. Torch lily might bloom late, so also prefers to wait until late winter. New Zealand flax recovers from the process more efficiently after winter. It grows slowly during wintry weather, so is more susceptible to rot.
Daylily is easy to divide by simply digging and separating foliar rosettes from each other. Lily of the Nile is as simple but more work because of tough roots. Shasta daisy involves cutting apart clumps of its matted basal stems. Each clump, which may be cut away with a shovel, contains several such stems. Newly divided plants might bloom better because they are not quite so crowded.
Highlight: Torch Lily
Once it gets established in a garden, it will likely always thrive there. Torch lily, Kniphofia uvaria, is as reliable and resilient as Lily of the Nile and African iris. It is as easy to divide for propagation too. Mature specimens can survive without any more water than they get from annual rainfall. They might appreciate some through the middle of summer, though.
Old fashioned torch lily blooms for summer or early autumn, so some are blooming now. Modern cultivars are more likely to bloom earlier. Densely conical floral trusses suspend many narrow and tubular flowers. They stand as high as five feet on otherwise bare floral stalks. Dense mounds of grassy basal foliage should grow no more than three feet high.
Flower buds are orange as they begin to bloom and then fade with age to pastel yellow. Because floral spikes bloom upwards from the bottom, they turn yellow at the base while orange on top. They resemble candy corn. Some cultivars are paler white at the base, or more reddish orange at the tip. Others are uniformly orange, yellow or soft creamy white.
