Some plants are often confused with each other, because of their appearance, their names, or because they are members of the same plant family.
This is true of peace lilies and calla lilies, and while they share some similarities, they have more differences than what they have in common.
Both plants make fabulous houseplants and may be grown outside if your climate is warm enough.
Here’s what you need to know about peace lilies and calla lilies, how to tell the difference between them, and how to care for them.
What Is A Lily?
Before going into the details of what makes these plants so different, it’s worth looking at why we call them lilies, as neither of them is related to the lily at all.
This is also true of daylilies, lily of the valley, canna lilies, water lilies, daffodil lilies, and voodoo lilies (see also How To Grow Voodoo Lilies), among countless others.
But why do we call them lilies? There are several reasons. One is that they were originally thought to be lilies, and they were then moved into different plant families, changing the botanical name, while the common name stuck.
Another reason is that they look like true lilies. True lilies belong to the Lilium genus, and many plants fall under this category.
Calla lilies look a little more like true lilies than peace lilies do. Calla lily flowers are large, come in many colors, and have trumpet-shaped blooms, but they belong to the Zantedeschia plant genus, so they are not true lilies.
Peace lilies aren’t related to true lilies, either. They come from the Spathiphyllum genus and produce spoon-shaped flowers, also known as spathes.
How To Tell The Difference Between A Calla Lily And A Peace Lily
Now you know that calla lilies and peace lilies aren’t related, here is how to tell the difference between the two, and there are quite a few!
Peace lilies start quite small, but some can get as large as 6 feet tall when they mature, spreading to 5 feet wide if the conditions are right.
The growth always emerges from the crown of the plant and has a clumping growth habit.
Calla lilies are much smaller than peace lilies. At the most, they get to around 3 feet tall, spreading about the same, but this is usually much less when grown as a houseplant.
The growth of a calla lily emerges from the rhizomes instead of the crown, from beneath the surface of the soil.
The leaves of a calla lily are small and shaped like the head of an arrow. They also come in a light shade of green, and some varieties feature white speckles on the foliage, too.
Typical of a herbaceous perennial, peace lilies feature wide and long, deep green leaves that are much bigger. They can reach as wide as 15cm, and up to 2 feet long.
You can get cultivars that have variegated leaves, but this is rarer than in calla lilies.
Perhaps the most obvious distance at a glance, after the size, is the flowers of each plant. They each have different shapes (designed to attract different pollinators) and are available in different colors.
Peace lilies have spoon-shaped creamy white flowers, which are modified leaves, called bracts. To some, it looks like the head of a cobra, and to others, it looks like a white flag of surrender or peace, which is where the common name comes from.
This plant is capable of flowering at any time indoors, if the growing conditions are right.
A calla lily produces tubular-shaped flowers, which surround the spadix, in different colors depending on the variety.
You can get them in pink, maroon, deep purple, yellow, orange, and white, and this makes them very popular with florists and as part of arrangements. Not only do they come in a range of colors, but they also last a long time as a cut flower.
The flowers of a peace lily are exclusively white, and while they can be used in arrangements, they are more likely to be given as a gift as a whole plant (see also Peace Lily Flower Meaning).
Calla lilies also only flower during summer, whereas peace lilies are capable of flowering repeatedly throughout the year if the conditions are right.
Sunlight And Position
Another notable difference between a calla lily and a peace lily is the growing conditions each plant prefers.
Calla lilies like a lot of water (see also How To Grow Calla Lilies), so much so that you can completely soak them or even plant them partially in the water, and they won’t mind. They also like a sunny position.
Peace lilies, on the other hand, while tolerant of some overwatering, will suffer from root rot if you give them too much too soon. While they like to have damp soil, constantly soggy soil is a shortcut to killing the plant.
Peace lilies droop dramatically when they need watering (which is a good indicator when they do want a drink).
The leaves can lie against the sides of the pot, looking completely dead until about twenty minutes after you have watered the plant when it will stand upright once more.
Peace lilies can tolerate a range of light levels, from bright and indirect to much darker areas with only a little light (though you will see far fewer blooms).
Calla lilies will survive outdoors in USDA zones 8 through to 10 if you’d prefer a magical display outside, while peace lilies are more particular, and will only survive in USDA zones 11 to 12.
How To Grow Peace Lilies
Peace lilies are used to warmer temperatures than calla lilies, so they do need to be kept inside unless you live in zones 11 to 12.
Set them a little way away from windows, which will give them adequate light but not enough to burn the leaves. Yellowing or browning leaves implies that the light is too strong, so change the position and wait about a week to see if the plant improves.
If not, change it again, until you notice that the leaves remain a healthy green. If you use tap water to give your houseplants a drink, use cooled kettle water, or let some of the chemicals dissipate by leaving the water in a bottle overnight.
When it gets hot, peace lilies benefit from an occasional misting to briefly help the humidity, but make sure to do this when the sun won’t touch the leaves, otherwise, it could end up scorching them instead.
They will weather cold drafts better than most tropical plants, and survive in temperatures between 65 and 85°F.
Peace lilies are also fairly resilient when it comes to pests, and you can prevent infestations by wiping down both sides of the leaves with a damp cloth once a week.
It’s worth noting that while these aren’t as toxic as true lilies, they do contain some harmful compounds, so keep them out of reach of pets and children.
How To Make Sure Calla Lilies Thrive
Calla lilies are beautiful plants that won’t survive any type of cold weather, as they have adapted to live in warm temperatures.
This is why many people keep them as houseplants rather than growing them outside.
If you do choose to grow them outside, and you live somewhere that gets frost, you will need to move the plant inside during the winter, or dig up the rhizomes and store them somewhere frost-free.
Calla lilies like lots of nutrients in the soil, as well as plenty of light. They will tolerate lower light levels, but they won’t flower as much.
If you are planting rhizomes yourself instead of buying an established calla lily, plant them about 15cm below the soil’s surface, and a foot apart from each other.
To sustain healthy growth, feed them in the spring using a 5-10-10 fertilizer, though a houseplant fertilizer will also do.
Should I Choose A Peace Lily Or A Calla Lily?
Both are fantastic options for indoor plants, but it depends on your preferences and the growing conditions you have, especially if you want to grow them outside.
If you like the simplicity of white flowers, and a plant that is a little tougher indoors, it’s worth getting a peace lily. It also helps that these plants are largely more affordable than calla lilies.
If you want more color choices, go for a calla lily, which is a little more difficult to look after, but no less beautiful than a peace lily.