How to Plant & Grow Ludwigia glandulosa (Cylindricfruit Primrose-willow)


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Ludwigia glandulosa growth and care in ponds
Andreea Filip / CC BY-SA 2.0

Ludwigia glandulosa, as it’s commonly called in the pond industry, is known among botanists by the mouthful of a name cylindric-fruit primrose-willow. As implied by this name, it belongs to the evening primrose family, Onagraceae. The genus Ludwigia contains 82 species, all of which are aquatic or semi-aquatic, and includes water purslane, water primrose, and water mosaic plant.

Ludwigia is a genus that was first designated in the 1700’s by Carl Linnaeus, popularly known as the father of modern taxonomy, and named in honor of the German botanist Christian Gottlieb Ludwig. Ludwig and Linnaeus were friends as well as colleagues, and wrote letters to each other for many years, discussing life in their respective parts of the world as well as plants.

Facts, Benefits & Uses of Ludwigia glandulosa

wood duck waterfowl benefit from pond plants Ludwigia glandulosa
Waterfowl species, such as this wood duck, benefit from the food provided by Ludwigia glandulosa via seeds and aquatic insects.

Most Ludwigia members, Ludwigia glandulosa included, have fibrous roots that help filter water and provide valuable habitat for fish and important aquatic macroinvertebrates, such as dragonfly larvae. In turn, these macroinvertebrates offer a nutrient-rich food source for fish, waterfowl, and helpful amphibians like frogs. The broad leaves of Ludwigia glandulosa aid in oxygenating water, while also providing shelter for fish and helping to regulate water temperature. It is even listed as an ecologically important species in aquatic ecosystems.

Found natively throughout much of the southern United States, Ludwigia glandulosatypically establishes itself in wetlands, ponds, and even ditches with significant and persistent standing water. In most states, the population is considered stable, but Ludwigia glandulosa is a slow grower and sensitive to threats like habitat loss and damage from boating and dredging. As such, it’s a threatened species in Indiana and endangered in Maryland.

Ludwigia glandulosa Fact Sheet:
PLANT TYPE
Herbaceous Aquatic Perennial
HARDINESS ZONES
USDA 5 – 11
LIGHT REQUIREMENTS
Full sun
BLOOM COLOR
None
BLOOM PERIOD
None
MAXIMUM GROWTH
Grows up to water’s surface (up to 91 cm or 36 in)
PLANTING DEPTH
Up to 91 cm (36 in) of water
WATER QUALITY
pH 6.0 – 7.2

Ludwigia glandulosa Growth, Hardiness & Climate

Ludwigia glandulosa growth and hardiness in ponds
Sor Betto / CC BY-NC 2.0

When found in the wild, Ludwigia glandulosa can be quite a slow grower as they need ample sunlight and nutrients. In ponds and aquariums, however, where those things are more easily monitored and regulated, Ludwigia glandulosa has the capability to grow fairly quickly. With ample lighting, growth can be as fast as half an inch per day, meaning that their full 3 foot height can be reached in about a month!

Warm waters, preferably between 70 and 80° F (21 to 26° C), and full sunlight are best for Ludwigia glandulosa, though they can tolerate partial shade and temperatures as low as 60° F (15° C) for short periods of time. Zones 5 through 11 work just fine, though they prefer the upper end of this spectrum.


How to Plant Ludwigia glandulosa in Ponds

Planting Ludwigia glandulosa in ponds
Sor Betto / CC BY-NC 2.0

Ludwigia glandulosa is easy to plant – you can either place the stems or roots directly in substrate, or use small weights if needed to hold them to the bottom of the pond until they develop strong enough roots to hold themselves in place. This plant does well in anywhere from only a few inches of water to up to three feet of water, as they will typically grow to accommodate the depth of water that they’re in. This is why Ludwigia glandulosa in aquariums is always smaller than those found in ponds or lakes. Open water as well as small crevices are both perfectly suitable, so long as they still have access to plenty of sunlight. Aquatic planting soil or gravel is recommended to hold these plants in place.


How to Care For Ludwigia glandulosa

Ludwigia glandulosa require ample CO₂ and soak up any phosphate and nitrates readily. Without the presence of even just trace amounts of the latter two, this plant will have a tough time growing. Ample sunlight is also needed, else the plant may die. You can easily tell whether Ludwigia glandulosa is getting enough sunlight by looking at its leaves – their characteristic vibrant red color will turn green without enough light.

When provided with ample amounts of lights and nutrients, Ludwigia glandulosamay grow quickly. To help prevent overgrowth, you can simply clip the plants. If desired, these clippings can simply be placed stem-first in substrate or weighed down to the bottom of the pond, where they will likely establish themselves with little effort on your part within a week or two.

If you decide to trim Ludwigia glandulosa, you can either replant the trimmings, or be sure to properly dispose of them. Do not allow them to simply float around your pond, as they’ll probably die and will degrade water quality as they rot. Clean any dead or dying plant matter from your pond daily to encourage healthy water quality.


How to Winter Ludwigia glandulosa

So long as your pond doesn’t fall below approximately 60° F, Ludwigia glandulosa should be just fine over the winter. If you live in an area with cold enough winters to cause freezing and you lack a pond heater or de-icer, you can either transfer ludwigia into an indoor aquarium, or simply purchase new plants in the spring as they’re not very pricey.


Is Ludwigia glandulosa Toxic, Poisonous or Invasive?

Though native to North America, Ludwigia glandulosa is typically a very slow grower in natural areas outside of the pond industry and as such is not classified as an invasive species anywhere. Nonetheless, if you live outside of this plant’s native range, make absolutely certain that you do not plant it in naturally occurring wetlands, ponds, streams, and the like. Keep it only in your personal aquarium or pond, to prevent any damage or disruption to natural ecosystems.

There is not much documentation regarding the toxicity of this species, so it’s likely safe for ponds and wildlife. Its widespread popularity, combined with some waterfowl nibbling on it in the wild, bolster this conjecture.


Is Ludwigia glandulosa Edible? Will Fish Eat it?

Active fish, particularly the more gregarious koi, may uproot Ludwigia glandulosa and nibble on the tender roots. This is perfectly fine, as it won’t hurt your fish and shouldn’t overly harm your plant. If this becomes a persistent issue, you can place rocks around the base of the plants that are heavy enough to not be easily moved. You may also transfer Ludwigia glandulosa to aquatic planting baskets to deter fish herbivory of the roots and shoots. Its leaves are fairly tough, and so should deter most fish from trying to ingest them.


Where to Buy Ludwigia glandulosa & Seeds? (UK & US)

Ludwigia glandulosa is a very popular pond and aquarium plant, and as such can be easily found at most aquatic nurseries, aquarium and pond retailers, and online outlets. You can get a bunch (3 or more plants) for only a few dollars or pounds.

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