How to Propagate a Peace Lily

Featuring clear white flowers and glossy green leaves, peace lily (Spathiphyllum spp.) brightens shady spots indoors and outside. One of the few plants to bloom well in indirect light, peace lily is often grown as a houseplant, though it also grows outdoors year-round in U.S. Department of Agriculture plant hardiness zones 10B through 13. Peace lily rarely produces seed, and dividing a plant into sections is the usual propagation method. This plant is poisonous to humans, dogs and cats.

Peace lily leaves grow from underground stems, and growing new plants from underground stem sections is the most reliable propagation method. The best time of year for propagating a peace lily is spring. Peace lily leaf cuttings are unlikely to produce roots.

Gently ease the peace lily from its container or carefully dig it up with a garden fork. Just beneath the soil at the base of the plant are small clumps of stems. Gently separate the clumps and their attached roots by pulling them apart. Pull away just a few sections or divide the whole plant. If you need to cut through the underground stems to divide the peace lily, sterilize the knife by wiping the blade with a cloth that was dipped in rubbing alcohol, before and after cutting the stems.

Sections of peace lily's underground stems grow into new plants in individual pots. Use containers with drainage holes when growing peace lily stem sections. Containers should be large enough to hold the sections' roots and 1 inch wider and deeper. A 3- to 4-inch-wide pot is usually about the right size.

Spread a 1-inch layer of well-drained, general purpose potting soil on the base of a container, and place a section top. Fill in the gaps around the peace lily section's roots with potting soil, and firm the plant gently in its pot. Water the plant until water appears through the drainage holes.

Sections of a peace lily establish best at warm temperatures and in bright, indirect light. Peace lily grows strongly at temperatures between 68 and 85 degrees Fahrenheit during the day and 10 degrees cooler at night. Cooler temperatures slow down the plant's growth and may prevent a plant from establishing.

Place peace lily sections in their containers in a draft-free spot out of direct sunlight. Water the developing plants when the potting soil surface is dry, applying water until it appears through the container drainage holes.

Seed is unlikely to appear on a peace lily because many varieties are infertile. If a plant produces seed, it is encased in the brown seed head that forms from the central flower spike. When the seed head is dry and papery, crush it to gather the seeds. Alternatively, buy peace lily seeds.

Mix 1 part sphagnum peat moss, 1 part vermiculite and 1 part orchid potting mix. Fill a 3-inch container with the mixture and finely sprinkle the peace lily seeds on top about 1/4 inch apart. Sprinkle a very thin layer of vermiculite until the seeds aren't visible. Water seeds using a fine rose spray attachment on a watering can until water appears through the container drainage holes. Put the pot in a plastic bag and place it in a warm spot that receives bright indirect light. When the second set of leaves on the peace lily seedlings appear, plant the seedlings in individual 3-inch containers.