Marginal water plants, meaning those growing at the edges or ’margins’ of the pond, are the most unappreciated, confounding elements of water garden landscapes. Like the plight of poor Cinderella, held in reproach by her evil step-sisters until she was found by her prince, marginals are thought of only after all the honeymoon allure and preoccupation with water lilies & lotuses has waned.
A water garden design that overlooks the complex beauty of marginals is sure to be banal and superficial. Besides aesthetically softening the transitional edge between rocky shorelines and the waterline, marginal aquatic plants create wetland-like spaces, which play a key role in keeping pond water clean & clear. Marginals are fabulous filters, consuming tremendous amounts of impurities and nutrients that would otherwise feed unsightly algae.
Since over 40% of all wildlife lives in wetland areas, marginal plants are great for attracting wildlife to your pond. They complete the water garden ecosystem. Marginal plants give toads, frogs and other amphibians protection from weather and predators. They provide shelter for birds and small mammals who drink and bathe in your pond, and the sweet nectar of many plant varieties attracts hummingbirds, butterflies and hundreds of other beneficial insects.
It is true that water lilies, like the bride at a wedding, will always remain the focal point in your pond. However, marginals plants, like a well chosen group of bridesmaids, can help set the stage for a wonderful marriage.
And think about it. Who wouldn’t want a gorgeous ’plant’ like Pippa Middleton around on their wedding day!
Shopping For Marginals – What to Look For
Hardy marginal plants are grown in the shallow areas of your pond, also know as the ‘margins’. They are great hiding places for amphibians, beneficial insects and small fish, and they create a fabulous transition between your pond and the surrounding gardens. Hardy marginal plants are also perfectly suited for Rain Gardens and Constructed Wetlands.
A sure sign of a healthy marginal is new leaf growth on the plant. A healthy marginal should be able to stand on its own in the pot without flopping over. If you pick the plant out of its pot by its foliage the plant, this indicates that the plant is well rooted. If the plant pulls free when picked up by the foliage it indicates that the plant has been recently re-potted in a larger pot and has not had time to establish its root base.
For plants that flower, it is best to purchase ones with buds, but not blooms, to ensure the flower will emerge in your water garden.
Choose a place along the edge of the pond or shelf and dig out a hole in the gravel the size of the base of the plant. Place the plant in the hole and spread the gravel around the base of the plant. Be mindful that each plant will have depth requirements and if in question, refer to that specific plant on our website. If you are not able to retrieve the information on a specific plants required depth, as a rule of thumb, go shallow.
To make an impressive show of your new marginal plants, it is best that they be planted in groups of odd numbers such as 3’s, 5’s and 7’s, while staggering the plants. Be sure to put larger plants at the furtherest point from your viewing area to ensure you are not going to be blocking the view of the beauty of your pond with large plants up front. It is also a nice idea to plant shorter growing species at the base of taller plants to add depth and interest.
Avoid the use of concrete blocks or pavers to prop up your plants as concrete can leech lime into your pond increasing the PH levels.
Bare Root Planting
When plants are bare root planted in the pond it is beneficial to the overall health of the pond because the roots can grow unrestricted throughout the gravel removing nutrients from the pond and adding in the growth of the plant. Bare root planting of marginals is easy, simply rinse off the excess dirt from the roots, preventing the loose dirt from creating a cloudiness in your pond and algae blooms, and plant them as directed above.
There are some invasive species of marginals that should not be bare rooted as they will quickly take over your pond. Ask one of our plant experts for help in identifying such species. These plants can be enjoyed safely in one of our fabric planting pots.
Planting in Pots
It is a good idea to plant marginals in fabric planting pots using aquatic planting media. This also allows you to fertilize the plant directly without fertilizing the pond itself, which could cause algae blooms.
Plant your marginal in a pot that is one size up from the purchased size to allow room for growth. You can then create a pocket in the gravel, place the pot in the hole and cover the pot with gravel to give it a natural look.
The Great Divide
A marginal plants shows signs that it needs to be divided when the new growth is less or smaller than the previous years growth. This happens because the plant has become root bound which inhibits its growth.
To divide a potted marginal remove it from the pond and its pot. You may need to cut the pot and the roots of the plant to free it. Try to identify distinguished clumps within the plant that you can use as a guide for your division. If the plant has no obvious clumps cut the plant in half or in quarters. Once you have decided where you would like to divide the plant, using pruners a knife, or your strong muscles and pull apart, or cut the plant in the chosen areas.
Once you have divided the plant, cut back the foliage so that it equals the volume of the roots. This is done because the roots can only support an equal amount of foliage to roots. This may be hard to do as a plant lover, but it is to the benefit of the plant. Then re-pot the plant as usual, being sure to re-fertilize.
To divide bare rooted plants you may need some brut force along with pruners to get the plant out. Be very careful when doing this you cut only the plant roots and not the pond liner.
Overwintering Marginal Plants
Overwintering marginals is much like overwintering the perennials in your garden. Simply trim back the foliage leaving 6-12” of foliage above the crown of the plant. The additional foliage left behind acts as an insulation in the winter. If the plant is less then 12” in height, do not trim it back.
In the spring, when new growth is emerging, you can then remove the dead foliage, it usually comes out very easily. Aquatic grasses can be left uncut as they can provide winter interest. They can be cut back in the spring when new sprouts are starting to emerge.