Plants available for use in water gardens are many. Choosing these is a pleasure, but there are certain considerations to be taken into account. Most considerations, such as water depth, amount of sunlight, and how each species relates to its surroundings should have been considered during the design phase. Floating leafed and submerged plants are necessary for a healthy pond and must be included in your selection. The following is a partial list of cultivars of readily available plants by use group. For more information and prices, go to your favorite garden center and look at the stock, or write for catalogs from the many mail order growers found in garden magazines.
Floating leafed plants
Usually water lilies. Plant enough to cover 50 to 75 percent of the surface area of the pond, or approximately one for every 10 square feet of surface area (there are dwarf varieties for barrel gardens). Floating leafed plants will cover the surface of the water to a point that will, if done correctly, limit the amount of light reaching the depths of the pond holding algae growth in check. Thus, Lotus (Nelumbo spp.), which hold their leaves above the surface of the pond, do not contribute to this maintenance tool and are considered under Bog or Marginal Plants. Water lilies (Nymphaea spp.) are of two types, tropical and hardy. Tropical water lilies in turn are divided into day and night bloomers. Hardy water lilies are all day bloomers. Some hardy water lily flowers change color shades over the life of the bloom, adding to the character of these unique plants termed “Changeables.” Some available water lilies cultivars include:
Submerged plants are the oxygenators of the pond — a must if your pond is to be healthy and support fish. Submerged plants may become aggressive if planted in earthen ponds. Especially the first three listed which may take over a pond. The Texas Parks and Wildlife Department and the USDA have listed 12 species and one entire genus of plants on a list of restricted aquatic plants. These aggressively spreading plants are considered noxious weeds. The import, sale, purchase, propagation, or possession of any plant or its seeds on this restricted list is illegal without proper licensing and permits. In fact, many of these same plants are sold in the water garden catalogs since they are not restricted in states with colder winters. If you are unsure of the plants you are interested in, call the nearest Texas Parks and Wildlife office and request information. Roots of these plants are not used for nutrient or water uptake, but for anchorage, so oxygenators may be potted in gravel. Submerged plants should be stocked at a rate of one bunch per 2 square feet of surface area, in groups of 6 to 12 per pot depending on the size of the pot. Caging these pots is often advisable if the pond is to contain fish, which tend to forage on submerged plant foliage. Some available cultivars are:
Free floating plants
Free floating plants, though not absolutely necessary, add the finishing touch to a natural appearing water garden. These plants move with the breeze and produce an ever changing appearance for the pond. Functionally, they add to the oxygenators and produce varying casts of shadow that the pond owner and the fish will appreciate. Though in colder climates species such as Giant Duck Weed (Spirodela oligorhiza), Water Hyacinth (Eichhornia crassipes), and Water Lettuce (Pistia stratiotes), can be useful, they are restricted plants in the state of Texas. An example of one that is available that is not restricted in the state of Texas is described below.
Be aware when ordering from mail order catalogs that restrictions on plants vary among states and just because they are offered in the nursery catalogs does mean that it is legal to use them in Texas. If you are unsure contact your local Texas Cooperative Extension agent.
Bog or marginal plants
Though most are not grown for their flowers, some bog plants offer help for those unable to site their pond in sufficient sunlight for the majority of water lilies. Some plants can tolerate as little as three hours of direct sunlight. Some grow best in constantly moist to soggy soils, while others actually grow in standing water. There are many different species of bog plants with varying heights, textures and colors to their foliage. Plants for the bog garden or for margins of the pond add height and drama to the water feature; lotus, sagittaria, and dwarf bamboo add unique foliage, where iris, cattails, and sweet flag have unmatched upright linear texture. Some selections of bog plants are:
Plants to surround the pond
Many of the bog plants can be used in areas surrounding a pond. Other plants for use around the pond should be of a character that their reflection lends drama to the pond. Colorful flowers, attractive bark or fluted trunks, or other winter aspects can add to the seasonal interests of a pond. Avoid plants such as walnuts and willows that have leaves with allelopathic characteristics.
Planting the Pond
Planting the pond is the most exciting time and one of the most crucial. Spring is the best time to complete this task. Plants bought for the pond should be in top condition and installed immediately upon receipt if possible. Therefore, do not purchase the plants until you are ready to plant, or if ordering through the mail, plan their arrival carefully. Many mail order dealers ship their plants at only certain times of the year.
Plants bought from a garden center are often potted and ready to be placed in the pond. If not, or if you purchase your plants from mail order houses, they will come to you bare root, wrapped in plastic containing moist organic media or paper. These plants should be removed from the media, washed, and potted immediately upon receipt. Plan ahead and have your soil, fertilizer tablets, pots, and burlap, if you are using baskets, ready ahead of time.
Tropical lilies form crowns and should be planted in deeper pots. The crown should be placed in the soil near the top and covered with only as much media as is needed and then 1 inch of gravel leaving the growing point above the soil and gravel.
Hardy lilies grow from rhizomes and should be grown in wide shallow tubs or baskets. The rhizome should be placed in the soil at a 45 o angle and covered with soil and 1 inch of gravel. Be sure to leave the growing tip above the soil and gravel. Tropical and hardy water lilies should be covered with 6 to 18 inches of water.
Water lotus should be considered a bog plant, as they do not contribute to covering the surface of the pond as do the floating leafed water lilies. Water lotus grow from large vigorous banana shaped rhizomes and must have at least two nodes (the pinched looking area of the rhizomes) left on them when divided in order to survive. Their roots are brittle and can easily be broken, killing the plant. Lotus should be grown in large tubs or baskets no less than 32 quarts in size. Place the rhizomes shallow in the pot and cover with soil and 1 inch of gravel. It may be necessary to put a rock or brick over the tubers of these plants until rooted to prevent them from floating out of the soil. Lotus should be placed in the pond about 4 inches below the water surface. To place the lotus in deeper portions of the pond, put them up on blocks or bricks to achieve the proper depth. Place scraps of liner under the bricks to guard against punctures (Figure 5).
These plants often arrive in bundles of cuttings and should be planted as they are into pots and placed on the bottom of the pond. Their roots are merely for anchorage so they can be placed in sand, soil, or gravel.
These plants should be placed in pails or pots on the shelves of the pond where the crowns of the plants are covered by about 1 inch of water.
These plants should be rinsed well before placing them directly into the pond.