Spathiphyllum – Peace Lily (S. ‘Mauna Loa’)

Spathiphyllum commonly known as Peace Lily,originated in South and Central America.  They are stemless plants grown for their glossy leaves and arum-shaped flower heads.  The flowers are very similar to calla lily flowers, with a large white spathe surrounding an erect, 2 – 3 inch (5 – 7 cm) long spadix coloured white, cream, or green.  Flower heads appear on top of thin long branches in the same way as the leaves.  Spathiphyllum bloom mainly in spring and summer on long stalks that tower above the foliage.  The flower head is usually fragrant and keeps its original colour for about a week.  The spathe changes from white to light green, remains attractive for 5 – 6 weeks, and then becomes unsightly and should be removed.

The most popular indoor plant in the U.S. and U.K., most of the Spathiphyllum used as house plants, are hybrids.  Impressive foliage at the end of a thin, long branch with white flowers equally as impressive, are characteristics that make Spathiphyllum very popular for those who love foliage/green plants as well as those who prefer flowering plants.  One of the favourite plants of growers, many new varieties are being developed with impressive foliage, richer blooms, and are generally hardier than the plants available today.   

   S. ‘Mauna Loa’is a hybrid growing to 2 feet (60 cm) tall.  Its leaves are on stalks 10 – 12 inches (25 – 30 cm) long with the leaves being up to 9 inches (22 cm) long and 5 inches (12 cm) wide.  The flower stalks can be 15 – 20 inches (38 – 50 cm) long, and the pointed oval spathe backing the cream coloured spadix is 4 – 6 inches (10 – 15 cm) long and up to 4 inches (10 cm) wide.

   Plants that fail to produce flowers need to have the watering cut down and be moved to a location with more light.  They will produce more flowers if they are a little root-bound and get adequate light.  Spathiphyllum are very resistant to disease and insects.  The number one problem with spaths is over-watering, which causes root rot.  They are particularly susceptible to dry air and should be misted weekly and kept on a tray of moist pebbles.

Proper Care

Light  Spathiphyllum need to be grown in medium light during the summer and bright light during the winter.  Strong sunlight will burn the leaves.

Temperature  Normal room temperatures are suitable for these plants. 

Watering  Water moderately with enough water at each watering to keep soil moist throughout but allowing the top half-inch of the mixture to dry-out between waterings.  Over-watering will cause root rot and the plant will die.

Propagation  Divide overcrowded clusters of leaves in spring to propagate Spathiphyllum.  Pull rhizomes apart gently, making sure that each piece has at least two or three leaves attached.  Plant individual pieces in 3 inch (7 cm) pots containing a moistened mixture of equal parts peat moss and perlite or coarse sand, burying each piece at the same depth each rhizome was planted.  Treat each plant as mature spathiphyllums.  Do not fertilise the newly potted rhizome for three months.

Potting/re-potting.  Move plants into pots one size larger each spring until the maximum convenient size pot is reached.  Use a peat-based potting mixture or equal parts of potting soil and coarse sand or perlite.

Feeding  Fertilise with a standard liquid fertiliser every two weeks from early spring to late fall.  For plants that continue to grow throughout the year, continue feeding during the winter.

Special Problems

Red spider mites.  Spathiphyllum is susceptible to spider mites if the humidity is too low.  Mist-spray foliage once a week, making sure to spray under leaves, which is where mites occur.  If you do have an infestation, use a non-toxic pesticide (see recipe) to eradicate the problem.  If you would prefer to purchase a product, insecticidal soap will take care of the mites.  Follow manufacture’s directions carefully.

Non-toxic Pesticide

Use a handful of soap flakes, ¼ tsp. (1 mL) vinegar, and 1 qt. (1L) water.  Pour into a plant mister, only spray where needed.