Give Peace (Lilies) a Chance
by Ginny Stibolt

When we bought our house in 2004, the previous owners left us some porch plants including two pots of peace lilies (Spathiphyllum spp).  I'm guessing by their size that we have the 'Mauna Loa' cultivar, one of the more common peace lilies sold. There are about 40 species of peace lily distributed throughout tropical Central and South America. Most hybrids are derived from S. wallisii and S. cochlearispathum.  They are not true lilies, as discussed below, but earned the common name peace lily or white flag because the modified leaf, called a spathe, behind the inflorescence (flower head) looks like a white flag of surrender.

Peace lilies are popular, tough houseplants and office plants that thrive in relatively low light.  They are also known for purifying the indoor air by removing toxic gases such as benzene and formaldehyde.  While all green plants extract carbon dioxide and produce oxygen during photosynthesis, NASA found 19 houseplants that can grow under low light conditions and can also absorb various toxic gases that can build up in indoor spaces.

Our peace lilies have graced our porches, but mostly we like them in the house.  Some people say they need to be constantly damp, but ours get watered only once a week or so.  Too much water may cause root-rot. After more than four years under our care, one of our pots of peace lilies was wilting too often, had brown tips on its leaves, and the leaves had lost their typical dark green shine. This winter I finally got around to repotting it.

Repotting the Peace Lily

When I tapped the lilies out of the pot, I inspected the roots.  As I suspected, they were root bound and this problem was compounded by the pot's being only half full of soil and having a lot of potshards in the bottom.

While we've been told over and over again by "gardening experts" to use a generous layer of potshards or gravel in the bottoms of our pots to aid drainage, it's simply not true—an old gardeners' tale.  It was shown more than 100 years ago that the flow of water from the soil is actually impeded when moving from a fine medium like soil to a coarse medium such as gravel or potshards.  Besides when you think about it, the plants in a container are under enough strain already, it just makes sense to provide as much active growing medium as possible.  

So after I tipped the peace lilies from their pot, I untangled the potshards from the roots and removed as much soil as I could. Then I rinsed the roots and leaves with rain barrel water.  There was no reason to retain any of that soil--after years in the pot, it didn't have anything to offer the plant.  I placed the spent soil on top of a compost pile where it will be rejuvenated as it's incorporated into the compost.  

I scrubbed out the same pot with a brush and rain barrel water, placed a handful of leaves and pine needles in the bottom of the pot to keep the soil from running through the drainage hole, and filled the pot halfway with finished compost.  I then placed the whole group of plants back in the pot. I could have separated some of them out to start a new pot, but since there will be much more soil than before, I didn't think it was necessary to reduce the mass of plants.  From what I've read, peace lilies prefer a crowed pot.  Finally, I filled in and around the roots with more compost and added a generous amount of water as I was filling in to prevent large air spaces. 

This same pot a few months later has lots of new growth and is flowering.  The yellow/brown tips on the old leaves still show, but the new leaves look great.  The male flowers are now in bloom and their nearly white pollen is sprinkled on the leaves below the flowers. >> 

The Araceae Family

Peace lilies are not true lilies, which have six tepals as we discussed in A Plant by Any Common Name, but are part of the Araceae plant family also known as Arums.  The flowers are grouped in an inflorescence mounted on a thick stalk, which is underlain or surrounded by a spathe.  The spathe can be relatively flat as in the peace lily or it can wrap around the inflorescence like the calla lily (Zantedeschia aethiopica).  The spathe can also be shaped like a hood as in a jack-in-the-pulpit (Arisaema spp).  The whole flowering structure is called a spadix.

<< The spathe on this calla lily is an attractive burgundy with a golden border.  Ever since I first heard Katherine Hepburn say, "The calla lilies are in bloom again..." in the movie "Stage Door," I've wanted to have some in my garden.  Here in north Florida, our climate is perfect for these beauties. Their spotted, arrow-shaped leaves are also attractive. 

Most members of the Araceae family contain oxalate crystals, which are irritants and may be toxic. Ironically the tubers and roots of some members of this family such as wild taro (Colocasia esculenta) have been extensively used as a basic food.  It must be dried and cooked to break up the crystals.  Taro was imported from India to feed the slaves and now it's one of Florida's most invasive weeds.

Other members of this widespread and well-known family include: athuriums (Anthurium andreanum), skunk cabbage (Symplocarpus foetidus), dieffenbachia (Dieffenbachia picta), philodendrons (Philodendron spp), monstera (Monstera spp), Chinese evergreens (Aglaonema spp), caladiums (Caladium spp), and many others.  Philodendrons, Chinese evergreens, and dieffenbachia were also included in the NASA study and can all remove toxins from the air. 

Peace Lilies are Great Office & House Plants

I hope you'll try some beautiful peace lilies in your home or office, and as an extra bonus they'll remove toxins from your indoor air.  When they need repotting, they'll tell you like mine did.  And when they are happy they'll reward you with their shiny dark green leaves and their striking, white flag flower heads.  Peace!

Resources:
· The Informed Gardener book and website provide myth-busting, scientific evidence for many gardening practices including the potshards or gravel in the pots: www.informedgardener.com 
· For more information on the Araceae plant family: http://en.wikipedia.org/wiki/Araceae
· The 19 plants that NASA studied: http://en.wikipedia.org/wiki/List_of_air-filtering_plants 
· Dr. Wolverton did the research for NASA and provides more details: http://www.wolvertonenvironmental.com/airFAQ.htm 
· I've covered compost and care of container gardens Sustainable Gardening for Florida in my book:
· For details on Peace Lilies with a link to care and feeding: http://davesgarden.com/guides/articles/view/1953/ 

Ginny Stibolt would like to hear from readers who have suggestions and questions. After all, there are more than a few transplanted gardeners here in northeast Florida trying to figure out what works and what doesn’t in planting zone 8/9. She's written a book, "Sustainable Gardening for Florida," to be published by University Press of Florida in 2009. You may contact her or read extra details on her articles and other information posted on her website: www.transplantedgardener.com.

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