Last Updated: 2/12/20
Introduction to Marginal Plants
For a list of hardy marginal plants, see the marginal plant list.
Marginals are also sometimes called bog plants or emergent vegetation. Technically, bog plants are those that require acidic, wet soils. Marginal plants have their roots and lowest stalks wet most of the time. Their leaves and flowers are held above the water. Most require dirt or gravel to root into and grow in the shallow regions of the pond. In hobbyist ponds, they are most often potted up with clay dirt topped with pea gravel in 1 to 5 gallon pots. Depending on the plants' growth rate and pot size, they require repotting every 1 to 3 years. Fertilizer pills can be added every month during the summer but may not be necessary. Because they are mostly out of water, fish do not usually bother or eat marginals. Fish may eat the first growth but, if the lip of the pot is near to the water level, the fish cannot get into the pot.
Creeping plants which send out runners all over are also considered marginals by some (and in my lists) but their foliage is usually very close to the surface. Sometimes, they can have leaves under water. Running plants include parrot feather (which also can grow under water sometimes), four leaf clover, water poppy, and primrose creeper. Creeping or running plants can be propagated by cuttings.
Iris are a type of marginal that I include in a different list due to the large number of varieties available. This shortens the large marginal list considerably.
Lilies, lotus, and lily-like plants are also marginals in some ways but I have included them under a different heading due to their uniqueness. Unlike most marginals, their leaves and/or flowers often float on the water.
Watercress is a special plant because it can grow in the waterfall or stream. A few other plants like water celery, parrot feather, and primrose creeper can grow in moving water but not as easily as watercress. The scientific name for watercress is Nasturtium officinale but there are similar species. It grows in water that is constantly wet up to six inches deep. It spreads by runners out to only about four inches from the roots in the water. Watercress can survive in Zones 4 to 9 or 10. While it can do well in partial shade, it also does well in full sun, at least in the spring. During early spring, watercress sprouts many small, white flowers. A few mail order pond suppliers sell watercress but the easiest way to get some is at the grocery store where it is sold as a green for salads. It should be safe for human and fish alike to consume. Most often, it cannot be grown within reach of plant-eating fish (they will eat it all).
The watercress sold in grocery stores does not usually have roots. It can be placed in a bucket of water or secured with rocks into the moving water where it will root within a week and can be relocated if needed. Watercress will not do well in water with little movement or deep water. The benefits of watercress include filtration of the water all year long and at least one plant that will grow in fast moving water. In moving water in Zone 7, it remains green (at least under the water) all year round. It grows best during the spring and fall and dies back in the summer and winter. While it can grow so much as to divert waterfall flow, careful removal of excess growth should prevent this. Watercress should be anchored with small pea gravel or stones. While it will grow in dirt, watercress will remove more nutrients from the pond water if planted in gravel.
For a list of places that sell watercress plants, see my marginal plant list under watercress. One place that sells watercress seed is The Cook's Garden. Their phone number is 1-800-457-9703. Another place is Territorial Seed Company with a phone number of 541-942-9547. For some recipes and information on watercress as food for us humans, see watercress.com.
The December 2002 newsletter has a long paragraph on planting watercress and more watercress information that I wrote. I also mentioned it in other newsletters.
Photos are listed from newest to oldest.
Watercress in flower in the waterfall on 6/4/17.
Watercress in the waterfall, facing east
I took these photos on 5/19/10. Water celery is also in both pictures.
White watercress in flower.
Yellow watercress in flower.
Watercress in Flower on 6/2/09.
Watercress and Water Celery on 6/2/09.
Yellow-flowering watercress - taken
6/21/08. My mother gave me some watercress but this one turned out yellow!
White-flowering watercress - my regular watercress was flowering the same day, 6/21/08.
Photo of watercress flowers, close-up,
Photo of waterfall with flowering watercress and water celery, 5/21/04.
Photo of the waterfall with flowering watercress, facing south, 6/23/03.
Photo of the waterfall with flowering watercress and water celery, facing north, 6/23/03.
Photo of the waterfall with about-to-flower watercress, facing Northeast on 5/27/02.
Photo of the pond and waterfall covered in flowering watercress, facing north, 6/3/01.
Picture of watercress flowering on waterfall, facing south, 5/23/00.
Picture of watercress flowers, closeup, 5/23/00.
Picture of watercress flowering on waterfall, facing northeast, biofilter in upper left, 5/23/00.
Picture of watercress overloading the waterfall, facing north, 8/11/99.
Picture of watercress overloading the waterfall on the left, facing south, 8/11/99.
Picture of watercress on waterfall, facing north, 8/11/99.
Picture of flowering watercress in the waterfall. The white blooms are hard to see, 5/28/99.
Picture of the waterfall with watercress in the center of the photo among the rocks, looking from the biofilter down into the salvinia and water hyacinth covered deep end, 9/19/98.
Water celery (Oenanthe javanica) is another great plant for vegetative filters. Some people call it water parsley. It may also go by the names "Daun Silom," "Chi Lawn," "Shellum," or "Sui Karn" in various Asian languages as it grows wild there. It grows very fast when rooted in gravel and consumes many nutrients. The lush growth sprouts a lot of white flower bunches in late August which the bees, moths, butterflies, and wasps (even the ones that ordinarily are carnivorous cannot resist) just love at my pond. The flower bunches look like Queen Anne's lace except that there is not center dark flower. Water celery can tolerate some moving water. A combination of watercress, water celery, and parrot feather comprises the majority of the vegetative filtration occurring in my waterfall and waterfall exit areas. In my pond, water celery is eaten by the fish where they can get it, by the deer, and by my mother. It grows very well and in ideal situations, it will take over. Water celery is one of the few pond plants that will both take having its roots freeze solid and will also jump the pond and grow on dry land. I have had it jump two of my ponds where it now grows in the mulched perennial beds as well. It does not grow as lush there and has rarely flowered on dry land. Of all the pond plants that I have, I would say that water celery is the closest to being a "weed" in the way that it grows and spreads. I love weeds! It is not native to the USA.
Water Celery Photos:
There are many photos that happen to include water celery on my pond
photos page. Here is an example:
Pond facing northeast. You can see the water celery in the waterfall.
These photos are from 4/1/09.
Water celery in the waterfall area, top view.
Water celery in the waterfall area, frog's eye view.
Water celery at the bottom of the waterfall on 5/6/13.
Parrot feather is a common hardy plant to grow in ponds. It is more commonly called parrot's feather which is incorrect because that is easy to pronounce. It is not native to the United States. Myriophyllum aquaticum is the scientific name. Parrot feather is very versatile. It will grow somewhat submerged but will have "feathers" or leaves far apart and yellowish. If allowed to grow as a marginal with its roots in dirt or gravel, it will send up soft whorls of green leaves a foot or two straight up off the surface. At night, the leaves close up. Parrot feather will also grow in a stream. It can be broken into pieces and all will root. Parrot feather does not flower. In order to benefit from its nutrient-removing capabilities, it is best to root it in a shallow bed of pea gravel or a pot of pea gravel. It can also be left free but the roots will eventually find a holding spot. Interestingly, while parrot feather did extremely well in my pond from 1997 to 1999, it decreased in quantity in 2000 when water celery started growing in its main spot. By 2001, all my parrot feather was gone so I bought some more. There are photos of my parrot feather on my pond pictures page when it was king of the pond.
On 8/21/07, Frank sent me photos of a plant to identify. Neither he, some people he has consulted, or I can determine for sure what species it is. Do you know? If so, please contact me, and I will let him know. Here are the photos and some of what he wrote to me.
"I have a one year old pond that used to be a swamp/bog/woods. It's now only a couple of feet deep, and I'd like to attract wildlife, birds and possibly red winged blackbirds. I've had a couple of green herons so far. I have a lot of frogs and a dozen bluegills in the pond. It's about 150' by 60'. I have some wide blade plants popping up throughout the pond. Should I remove them all, leave them alone, or just move them to an end to provide cover for the wildlife? Is it invasive? What are your thoughts on transplanting some cattails into the area? It's rather shady so I don't know if they will survive. Are there any plants that you can recommend that will be good in this environment? We have a lot of deer in the area so something they rather not eat would be helpful...."
I suggested it might be sweetflag which has the rib along the stem. However, it smells when crushed which he says below, this does not.. I had thought he said where he lives but re-reading it now, it seems he did not.
"I brought it to the local pond expert, and he feels it might be nutsedge. I don't think it is because the stem is not triangular. The plants have a horizontal base. The leaves are very similar to an iris but crushing them does not release any smell. There is a distinct raised sharp rib on the back of each leaf. Do these clues help any?..."
On 6/15/10, Rebecca sent me an e-mail. She thinks the plant is swamp lily, Crinum americanum.
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