How to Plant & Grow Bog Arum (Calla palustris)


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Bog arum is a great ornamental plant to consider due to its white flowers and glossy leaves. Aiwok, CC BY-SA 3.0, via Wikimedia Commons

Also known as bog arum, marsh calla, water arum, water dragon, and wild calla, Calla palustris is the only member of the Calla genus. Interestingly, calla lilies such as Zantedeschia aethiopica are not included in this genus.

Bog arum is in the Araceae family, which consists of plants that have specific, uniquely-shaped flowers. Peace lilies are perhaps the most well-known member of this family, and have flowers with a similar shape to bog arum. Bog arum’s flowers consist of a large white segment surrounding a greenish-yellow cluster of tiny flowers called an inflorescence.

Bog arum is native to wet soil in the northern areas of North America. When this plant’s flowers are spent, bright red berries appear in their place. Bog arum’s white flowers, red berries, and glossy leaves make it a great ornamental plant to consider.

Facts, Benefits & Uses of Bog Arum

Although bog arum does not produce a particularly strong or pleasant scent as far as humans are concerned, it does still attract organisms such as various pollinators, beetles, and even snails. This plant’s creeping rhizomes help it to form dense colonies underwater that can even interfere with the ability of boats to pass through. These same rhizomes provide important habitats for aquatic invertebrates and various fish species, which use the plant as shelter for spawning and safety from predators.

Bog arum’s actual flowers are barely visible and are sometimes confused with simply being pollen! Actually, the white segment of bog arum is not part of the flower, but is actually a spathe, a modified leaf.

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Bog Arum Fact Sheet:
PLANT TYPE
Herbaceous Aquatic Perennial
HARDINESS ZONES
USDA 2 – 6
LIGHT REQUIREMENTS
Full sun to partial shade
BLOOM COLOR
White
BLOOM PERIOD
May – June
MAXIMUM GROWTH
Height: 6 – 16 in
PLANTING DEPTH
5 – 15 cm (2 – 6in); deeper for mature plants
WATER QUALITY
pH 5.5 – 8.0

Bog Arum Growth, Hardiness & Climate

Bog arum is known to spread through rhizomes. Lazaregagnidze, CC BY-SA 3.0, via Wikimedia Commons

The growth rate of bog arum is moderate, with plants reaching a full height of six to sixteen inches. More significant than their height, however, is their spread. Bog arum spreads through rhizomes and can form dense colonies underwater. Because of this, take care when deciding whether to plant bog arum in your personal pond.

Bog arum is hardy in zones 2-6, which means that it is acclimated to cold seasonal weather. As a perennial, it should survive the winter in these hardiness zones. Blooming typically occurs from May to June, although some blooms may stick around into July. Bog arum’s stalks will grow stronger if the plant is given access to full sunlight and plenty of moisture.


How to Plant Bog Arum In Ponds

Bog arum grows well in the shallow water of a pond. H. Zell, CC BY-SA 3.0, via Wikimedia Commons

A fairly easy plant, bog arum is commonly grown in ponds. Due to this plant’s propensity for spreading into dense colonies, it is worth considering planting in a container such as a pot or planting bag. This will not totally limit spreading however, as this plant also propagates through seeds. Bog arum will be happy on the margins and in the shallow water of a pond, or simply in very moist soil. The maximum depth underwater is about ten inches for a mature plant.


How to Care For Bog Arum

The white segment of bog arum is not actually part of the flower, but is in fact a spathe, a modified leaf. Florian Grossir, CC BY-SA 3.0, via Wikimedia Commons

Bog arum prefers damp conditions and plentiful sunlight. Ideally, this species would be planted in the shallow of your pond where you won’t have to worry about providing additional water. The most important element in caring for this plant is ensuring that its soil doesn’t dry out. Partial shade will likely result in a plant that has fewer blossoms and weaker, more limp stems and leaves.

If you feel that your bog arum plant is spreading more than you would like, you can dig up some of the rhizomes and divide the plant. Be sure to clean any trimmed or dropped detritus from the plant to maintain healthy water quality in your pond.


How to Winter Bog Arum

Bog arum is native to North America and is able to survive winters in hardiness zones 2 through 6. There is no need for any special treatment to prepare bog arum for the winter in its native zones. Bog arum is a perennial, so you should expect to see it in your pond for multiple years if you choose to plant it.


Is Bog Arum Toxic, Poisonous or Invasive?

Bog arum is native to North America and is technically invasive outside this range. It is not an extremely aggressive plant but will become widespread and form large colonies if allowed. As always, try to only use plants native to your specific region in your garden or pond. Regardless of where you live, it is a good idea to only plant bog arum in pots if you want to limit its spread through rhizomes. However, this plant also spreads through seeds.

All parts of bog arum are poisonous to humans, so consuming this plant is not recommended!


Is Bog Arum Edible? Will Fish Eat it?

Uncooked bog arum is not edible for humans, as every part of it, including berries, is toxic. However, it has been used as a food source at various times of scarcity because its roots are a great source of starch, since most of the toxicity is gone after roots are boiled. It has also been used for various medicinal purposes. This is a popular plant for ponds with fish and is presumed safe for fish to encounter, especially since it has a reputation for having a bitter and unpleasant taste.


Where to Buy Bog Arum & Seeds? (UK & US)

Bog arum is easily obtained at plant nurseries throughout its native range. Elsewhere in the world, you will likely have to order it online if you are set on growing it in your own pond or garden. As always, please take care when selecting plants that are not native to your area. In addition, be sure to only plant aquatic plants in your own personal pond so as not to spread plants in the environment.

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