Flower of the Week: Peace Lily

The peace lily is an evergreen herb in the Araceae family, native to the Central and South American tropics. Today, it’s one of the most popular green indoor plants worldwide, and you have likely seen it in a variety of settings.

Peace lilies are almost stemless, have large leaves, are caespitose and very ornamental. Properly cultivated, they can bloom frequently, producing white or greenish upright “flowers.” As with other plants in the Araceae family, the “petals” of peace lily are spathes, and the pale yellow “stamens” within them are true spadixes made of many florets.

A Symbol of Peace

In German, peace lily’s name is “Friedenslilie,” which suggests a similar meaning as in English: a state of truce. It was named so because of the white spathes, which are like white flags raised high. According to international law, in war the white flag stands for ceasefires, peace talks, or neutrality, and so is naturally a symbol of peace.

What's Wrong with It When the Leaves Turn Yellow?

Although peace lilies are easy to care for, there are times when the leaves suddenly turn yellow, catching people off guard. In general, the following reasons may make the plants unwell.

Over-watering. This is the most common cause of yellowing leaves. Too much water prevents the roots from breathing, resulting in the yellowing of leaves and even wilting of new shoots. Wait until the soil dries thoroughly before watering.
Sunburn. Leaves turn yellow, develop yellow-brown spots, and even dry up to die. Direct sunlight should be avoided.
Overly low temperatures. Peace lily is a tropical plant. When the temperature gets too low, old and new leaves both yellow. Please move the pot to a warmer place.
Over-fertilizing. Using slow-release fertilizer in small pots can cause excessive fertilizer accumulation, which is toxic to plants. Remove the plant from the pot with the root ball in soil, water it thoroughly, and then place it in a sink to let the water seep out, washing away some of the residual fertilizer. It's best to use a liquid fertilizer diluted to half the concentration the product manual instructs.
Pests and diseases. Mites can cause yellowing leaves. Please use a miticide.
Repotting. No matter how careful you are, repotting will damage the root system somewhat. However, there is no need to worry, as it will naturally get better after resting for a while. During the recovery period, protect the plant from direct light completely and don't let the environment get too dry, too hot, or too cold.

Be Careful of Toxicity

Although it’s one of the most common indoor plants, it’s still important to keep in mind that the whole peace lily plant is toxic to humans and pets. Do not eat it by mistake. The toxicity comes mainly from its calcium oxalate crystals, which are present in large quantities in the sap from broken stems and leaves. Direct contact with these crystals with the skin or mucosa can cause varying degrees of discomfort, and in some cases can induce severe allergic reactions.

Can I Grow Peace Lily Well?

Peace lily likes warm and moist environments. It is tolerant of shade but intolerant of direct sunlight, drought, and waterlogging, and doesn’t survive cold. Only when the winter temperature stays above 15°C (60°F) can the plant survive outdoors. For this reason, peace lilies are commonly grown potted and indoors.

To pot peace lily, use a commercial potting mix soil that is loose, fertile, and has a good water retention. Add a handful of bone meal as base fertilizer in the pot. The pot must have drain holes.

Peace lily can be kept indoors all year round. Scattered sunlight is its best source of light. Keep direct sunlight away in summer and let it receive more light in winter. Despite being shade-tolerant, peace lily will only bloom if it gets sufficient scattered light. It’s also important to keep it away from air conditioning vents, heaters, fireplaces, etc. when placing the plant indoors.

To reduce mold diseases, it’s best to wait to water peace lily when the leaves show slight signs of dehydration: when they start to droop, for example. Generally speaking, water about every 4-7 days. From spring to late summer, apply a compound fertilizer once a month at half the concentration indicated in the instructions. During the plant’s growth, if leaves show any signs of withering, remove them promptly. In the flowering season, whole scapes should be cut off as soon as the pollen is shed to retain nutrients.

During its growth season, peace lily will reproduce via rhizomes. Therefore, depending on the size and growth of the plant, repotting is necessary every 1-2 years. Repotting should be done in early spring or at the end of the flower season in the fall. While repotting, plant division can also be performed.

Size: 10-50 cm tall

Hardiness: For open-field culture, USDA Hardiness Zones 10-12

Light: Half shade to full shade

Soil: Fertile, well-drained soil

Bloom time: Late spring, early fall