Bog bean, also commonly referred to as buckbean, is a species that is native to much of Asia, Europe, and North America and is endangered in Korea and portions of the United States.
In nature, they only occur in bogs and fens, making them a diagnostic species. Diagnostic species are those that only exist naturally in one or two habitat types, therefore making them particularly useful in identifying and defining habitat types and their overall health and quality. As with most plants that exist in wetlands, menyanthes is exceptional at water filtration and also provides excellent habitat for dragonfly adults and larvae as well as a host of other semi-aquatic macroinvertebrates, such as damselflies.
Nestled within the Menyanthaceae family of aquatic plants, bog bean belongs to the Menyanthes genus, of which it is the only species. A perennial aquatic herbaceous plant, bog bean has trifoliate leaves and unique star-shaped white flowers that are fringed with white hair-like structures, which aid in both attracting pollinators and collecting pollen. These hairs also help to protect the flower’s nectar from small insects like ants, as they don’t assist in pollination. All manner of bees and other pollinators (such as hummingbirds, flies, and butterflies) utilize menyanthes, but in particular it is a favorite of bumblebees.
Bog Bean Growth, Hardiness & Climate
Bog bean can grow up to 16 inches in height with a rhizome spread of up to 60 inches per plant, and does best in emergent habitats where water is between 1 and 6 inches deep. It can also tolerate saturated soil with little standing water, but prefers more aquatic habitats.
This plant spreads both via seed dispersal and rhizomes, which sprout new stems and leaves and can form thick mats that float atop the water. This approach helps the plant to compete for space and resources in nature, but could be troublesome for your pond – you’ll either need to regularly trim the rhizomes or else plan on having this plant in a pond without many other plants.
As an ephemeral plant, it typically blooms in the spring and only continues through early summer (depending on the region). Since bog bean grows well in hardiness zones 3 through 10, this means it’s quite hardy and can tolerate quite cold temperatures (as low as -40° F), but also more mild temperatures ranging between 50 and 75° F (10-24° C). They do best in full sun and will struggle in the presence of shade – this is why they are active in the spring, while most other plants are just starting to come out of winter dormancy.
How to Plant Bog Bean
Planting in marginal pond edges works best for bog bean, as it prefers being in water where it can spread out. You can either place the Menyanthes in a container or directly in the soil, making sure that the roots plus about 2 inches of the plant’s stem is in the soil and at least an inch of water.
For younger, less established plants, place them in a pot and keep the soil consistently soggy. This will allow the roots and stem to grow hearty enough to survive in standing water. If you’re planting from rhizomes rather than a bare root plant, you can place the rhizome(s) directly in the water (again, in a shallow area) or on top of saturated, muddy soil at your pond’s edge where they can spread into the water.
How to Care & Maintain Bog Bean
Bog bean is a hardy herb and as such really just requires ample sunlight and plenty of moisture. As mentioned previously, they do spread via rhizomous mats. These can spread several feet and may overtake other plants, so simply cut back the rhizomes as needed. Once leaves and flowers start to turn yellow, trim them off to reduce organic matter in your pond and to encourage healthy plant growth.
How to Winter Bog Bean:
As a very hardy plant, it is not necessary to bring bog bean indoors for the winter. Instead, simply trim the plant so that it’s below the water’s surface or, if in a pot, move the pot into deeper water until the plant is submerged. Once ice thaws in the spring and there’s no danger of refreezing, move the plant back to either shallow water or saturated soil.
Is Bog Bean Toxic, Poisonous or Invasive?
Bog bean is not considered to be invasive so long as you’re planting it within its native range, which is quite widespread. Not much information can be found on the toxicity of this species, other than if too much is eaten it may cause stomach upset in humans. No information exists on its toxicity to wildlife, so it is considered safe for ponds.
As with any plant, make certain that you clean any plant clippings or dead leaves and flowers from your pond, both to maintain water quality and to ensure that your fish don’t become ill from consuming decomposing plant matter.
Is Bog Bean Edible? Will Fish Eat it?
Due to its bitter, acidic flavor, your fish, turtles, or any other critters are unlikely to try eating menyanthes.
Where to Buy Bog Bean? (UK & US)
Menyanthes is quite common, and can be found both online and at most aquatic retail stores. If you come across bog bean in the wild, please refrain from taking any as the wild plants are harder to care for and you would also disturb the delicate ecology of the wetland.
Can you advise how to get rid of bog bean please
Hi Christine,
If the bog bean isn’t planted directly in your pond, one of the easiest ways would be to simply allow the plants to dry out as bog bean is not at all tolerant of dry soils. It also doesn’t do well in shade, so you could potentially try shading wherever the bog bean plants are, but this could impact other plants, as well.
The most thorough, but also the most intensive, option is to manually remove the bog bean. Since they spread via rhizomes, this could be a bit of a tricky task as you’ll need to make sure to remove as many of the rhizomes as possible. This is actually one of the best times to do this, as fall should be encouraging the plants to start entering dormancy, and after removal they’ll have a harder time reemerging as winter sets in. You’ll likely need to repeat this process in spring for any plants that you happened to miss!
I would definitely classify this as invasive!! I planted it in a pot in my pond and it grew really well and took over half the pond… cleared most of it out – hard work! It returned and overtook most other plants – so I have just decided to try and remove it totally….. My husband and I have spent half a day in waders with spades, forks and rakes and have managed to take out about half of it…. this is a pond about 20ft long by 10 ft wide – narrow ledges and 3 ft deep in the middle. The bogbean has made a thick mat about 18″-2ft all across the base of the pond – it has then made a floating mat on the water and crept up into the border around the pond as well…!
We have had to cut it out from the bottom, chop it into manageable chunks (my husband is a strong landscaper – they are big chunks!) it has attached itself like glue to everything in and around the pond…. it will be another half day of back-breaking work to get it all out…. goodness knows if every tiny piece will re-root….
If anyone is thinking of putting it in a garden pond – DON’T!!!
Hi Jo,
Thank you for reading and for sharing your experience!
We always input in our plant guides the native region(s) of that particular plant, and include a disclaimer regarding any invasiveness outside of these areas. We welcome any further input regarding this, and echo your statement – please do not plant bog bean if it’s not native to your area, or any other invasive plant! Bog bean, and other plants that spread via rhizomes and fragments, should only be planted if it’s possible to cut back the plants on a yearly basis to help prevent them from overtaking everything else. If you (or any other readers) are interested, this site lists all native plants within your zip code if you live in the US: https://www.nwf.org/NativePlantFinder/Plants
It also includes more information on each species if you click on them, and any pollinator species that utilize it. It’s an incredibly useful tool when planning out any sort of garden, and actually restoration ecologists even make use of it!
Can I ask how long the bog bean has been growing in your pond?