How to Plant and Grow Canna Lily in Ponds (Canna Cleopatra)


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Red and yellow canna lily canna cleopatra
Canna lilies remove excess carbon and phosphorous from water, while also attracting useful pollinators.

Canna lilies are hybrids, with natural canna species hybridizing as well as people creating more hybrids to obtain different bloom color combinations. Canna cleopatra is one of the most highly sought-after varieties, with striking yellow, orange, and red petals and broad tropical leaves, but it’s an unstable hybrid, meaning that it can be difficult to recreate exactly. Considered to be taxonomically unique, cannas exist solely in their own family: Cannaceae.

Native to Central and South America, many canna hybrids now have a parent species that is native to North America, as they’re quite popular as decorative plants. However, they are a tropical species, and do best in temperate to tropical climates, as they cannot survive extended periods of cold or drought.

Facts, Benefits & Uses of Canna Lily

One variety of canna, canna edulis, has starchy, edible roots that can be eaten raw, cooked, or after being dried and ground into an arrowroot powder to be used in cooking. Though not considered toxic, canna cleopatra, on the other hand, isn’t viewed as being particularly palatable.

Due to their brilliantly colorful, large flowers, bees, butterflies, and moths are all frequent visitors of this plant. Wastewater treatment and wetland remediation studies have found canna lilies to be exceptional at removing excess phosphate and phosphorous, as well as carbon and nitrogen without adding to the biological oxygen demand put on the ecosystem. As an added bonus, cannas are pest resistant!

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Canna Lily Fact Sheet:
PLANT TYPE
Herbaceous Perennial
HARDINESS ZONES
USDA 3 – 11
LIGHT REQUIREMENTS
Full sun
BLOOM COLOR
Yellow, red, orange
BLOOM PERIOD
June – September (Summer to early Fall)
MAXIMUM GROWTH
Height up to 90 cm (35 in)
PLANTING DEPTH
2.5 – 5 cm (1 – 2 in)
WATER QUALITY
pH 6.0 – 6.5

Canna Lily Growth, Hardiness & Climate

As tropical plants, canna lilies require ample sunlight and soil moisture.

As tropical wetland plants, canna lilies do not survive well in dry areas or cold areas. From that perspective, they’re not particularly hardy – but given what they need (adequate warmth within zones 8 and above as well as moisture), they grow and live robustly and beautifully. Full sun will enable the largest, brightest flowers; in the shade, they will devote more energy to creating large leaves for capturing more light, and less to their blooms.

Their roots are actually rhizomes, meaning that they are able to spread and grow relatively easily without much, if any, assistance. They are pachymorphs, indicating that their rhizomes don’t spread indefinitely like that of invasive phragmites (the bane of ponders and ecologists alike), but rather end when they form bulbs or when the season freezes them out.

Cannas grow fairly fast, able to develop from bulb to mature, flowering plant in about 10 to 12 weeks. Some canna lilies can grow over five feet tall! Cleopatras, though, tend to grow to a maximum of around 3 feet or less. They are just as happy in moist soil as they are in a couple of inches of water.

Cannas typically bloom for 3 to 4 months during the summer, but can bloom year-round if you live in a tropical region with year-round moisture and mild temperatures. Each flower can last anywhere from several days to several weeks.


How to Plant Canna Lily In Ponds

Red, yellow, and orange canna lilies growing beside a pond
Vinny Carrasco / CC BY-SA

Canna “bulbs,” or, more accurately, rhizomes, should be buried with one to two inches of soil above them, and placed three or more feet apart to allow for proper growth. You should water the soil thoroughly after planting, enough to saturate down to the rhizomatous “bulb.”

They can also be planted along the shallow edge of your pond, either as rhizomes or as already established plants. This will eliminate the need for water every couple of days. If planted above water in soil, cover with a thin layer of mulch to help hold in moisture.


Canna lilies don’t need much – keep them in a fully sunny or mostly sunny area, and water sprouted plants every other day if the climate is consistently hot and sunny (i.e. during the height of summer). Plants that haven’t yet sprouted above ground, and those in cooler temperatures, can be watered only once or twice a week. Of course, if cannas are planted emergently in shallow waters, watering is not necessary. You’ll know they’re not receiving enough water if the leaves begin to crack and tear.

Sometimes, taller cannas with many flowers may droop over from their own height and weight. You can simply stake them to help them stay upright. Remove any dead or dying flowers from the plant, both to keep them from falling into your pond and degrading water quality as well as to help the plant more quickly devote energy to developing new flowers.


How to Winter Canna Lily

Canna lily is incredibly sensitive to frost, and as such the bulbs will need to be dug up in the autumn if you live below zone 8. Otherwise, the bulbs will freeze and then rot once the ground thaws. Canna lilies, particularly the cleopatra variety, are specially bred hybrids and as a result can be expensive. It’s best to bring the bulbs indoors for the winter, and replant them again in the spring.


Is Canna Lily Toxic, Poisonous or Invasive?

Canna lilies are native to South America, but they’re not a very aggressive species despite having rhizomes. Because of this, they’re not considered to be invasive outside of their native range, but instead of simply referred to as “non-native.” This is a term that is used by ecologists to describe plants that, while not native to the area, don’t really prove to be much of a threat to natural ecosystems.

Nonetheless, be careful to not allow cannas to escape your garden or pond so as to preserve the ecological integrity of the surrounding area!

No literature or research could be found on the toxicity of cannas, and in fact all species and all parts of the plant are listed as being non-toxic to humans, horses, dogs, and cats. Therefore, it can be reasonably assumed that it’s safe for your fish and other animals if they happen to decide to munch on some.


Is Canna Lily Edible? Will Fish Eat it?

Some varieties of canna lily are edible. Cleopatra lily in particular isn’t toxic, but also is not considered to be palatable due to a waxy, somewhat bitter substance on their leaves that helps prevent herbivory. This is the reason why they are largely pest resistant, though some caterpillars and beetles may still feed on them a bit. It’s unlikely that your fish or other animals will try to nibble on these plants, but if they do they should be perfectly safe.


Where to Buy Canna Lily Plants & Seeds? (UK & US)

Canna lilies can often be found at plant nurseries as well as home improvement stores that also have garden sections, as they’re beautiful and popular flowers. Cleopatra cannas, however, can be somewhat difficult to breed and may be harder to find. It’s more likely that you’ll find this particular variety via online plant and pond vendors.

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