UNCOMMON PLANTS FOR THE WATER GARDEN

Ask the average pond owner to list the first the first five plants that come to mind for the water garden, and the reply would probably include the following: water lily, lotus, cattail, water hyacinth and water lettuce. Maybe pickerel plant and duckweed would make the list – as would perhaps a few of the rushes. Most of us would not consider making pond plant selections by raiding our perennial beds, or by visiting the annual bedding plant, perennial, or shrub and tree departments of our favorite nursery. This is unfortunate – there are so many fantastic "land" plants that adapt wonderfully to the water garden. These plants contribute unexpected textures, colors, and rhythms, and add a new dimension to ponds when used in conjunction with typical water plants. They may also be used exclusively in the water garden – eliminating typical water plants allows the water gardener to create a unique design for the pond.

The Lysmachia family has many members that are quite common in Midwest gardens. They thrive in full sun to light shade and moist soil; therefore they work extremely well in the water garden. Lysmachia nummularia, known as Creeping Jenny or Moneywort features dime-shaped, bright green leaves along horizontally creeping stems. It is a semi-evergreen perennial, holding its foliage sometimes as late as December, and gives a show of cheery yellow blossoms throughout the summer. The variety ‘Aurea’ has vibrant golden leaves. Both can be placed on a marginal shelf with water up to the soil level, where stems will creep out across the water as well as trail over the edge to root in the soil outside the pond. Pots can also be placed in waterfall nooks, where the plants will cascade downward over the stones. Lysmachia clethroides, or Gooseneck Loostrife, is another perennial well-suited to the pond margin. It features arching spikes of white flowers in July and August, and thrives with constantly moist soil. Lysmachia punctata, known as Yellow Loostrife or Circle Flower, also a perennial, thrives in moist soil at the pond margin. From June into July, lovely yellow flowers with a brown circle in the throat appear. ‘Alexander’ is a shorter variety with crisp cream and green foliage. (Please note: Lysmachia is not the Purple Loostrife plagueing our wetlands- wild Lythrum also has the common name "Loostrife.) Finally, there is an annual Lysmachia that is a delightful addition to the waterfall or pond edge – Lysmachia ‘Outback Sunset’ features oval, variegated gold and green leaves, red stems, and yellow flowers with red centers throughout the summer. Part of the "Proven Winners" series of annuals, it is readily available in our market.

Perennial Creeping Buttercups – Ranunculus- often used as a groundcover - will grow with up to an inch of water over the soil level. A pot at the pond margin will perform similarly to Creeping Jenny. In a container water garden, the floating stems and yellow flowers in Spring create the effect of a minute water lily, although the leaves are three-lobed and incised, rather than round. Ranunculus repens ‘Buttered Popcorn’ has gold and green variegated leaves, and shiny yellow flowers. In the pond, Buttercups tolerate full sun to shade.

Ferns are not limited to the woodland garden, and many will tolerate higher light levels as long as their soil remains constantly moist. At the pond margin, moisture levels are maintained, and the ferns provide vertical interest and assorted textures. Osmunda regalis, - Royal Fern will thrive in full sun with "wet feet," as will Dryopteris thelypteris, - Marsh Fern. Matteuccia pensylvanica, the commonly used Ostrich Fern, as well as Osmunda cinnamomea – Cinnamon Fern will perform nicely in a bog garden or at water’s edge.

Many grasses and grass-like plants are ideal choices for pond use. Most Sedges – Carex - prefer moist soils, and will perform well with water one to two inches over soil level. At six to twenty-four inches in height, they provide a delicate vertical edging or groundcover at the pond edge. Their diminutive sizes make them perfect candidates for smaller ponds or container water gardens. Pointed, ribbon-like leaves come in shades of gold, green, and blue – there are also variegated varieties with white, green or gold accents. Variegated Manna Grass – Glyceria aquatica ‘Variegata’ – features foliage that emerges tinged with pink, changing to chartreuse with thin green striping in summer, and regaining a pink tinge in the fall. Several members of the Miscanthus family make stately additions to the large water garden. Reaching four to five feet in height, Porcupine Grass – Miscanthus ‘Strictus’ forms stiff, vertical clumps of green leaves horizontally banded with gold, and tolerates shallow standing water. Miscanthus ‘Variegatus’ – Variegated Silver Grass, makes a nice four to six foot specimen, with arching loose clumps of green and white leaves. From August to September, a deep wine-colored seed head appears.

Many members of the iris family make colorful additions to the water garden. Most are sold as perennial garden plants, although some are beginning to appear at water garden suppliers. (Ironically, a few of the varieties offered as garden plants were originally marsh natives.) Iris ensata – Japanese Iris, prefers a flooded root zone during growth and flowering, but needs dryness in the winter to avoid root rot. These requirements make it a perfect plant for shallow water gardens, where plants generally will not survive during the winter. Simply place the pot into the water garden, with water up to 2" over the soil level during the summer, then remove the pot in fall and bury in the garden, with soil to the rim, to overwinter. Unlike other irises, Japanese Iris have thin, two to four foot grassy foliage and large, flat, flowers with a texture like crepe-paper. Iris ensata ‘Variegated’ has vertically striped cream and green leaves that keep the garden interesting even when the purple flowers are gone. The Louisiana Iris, Iris fulvala louisiana, the Yellow Flag Iris, Iris pseudacorus, the Blue Flag Iris, Iris versicolor, all will add color and vertical accents to the pond. Overwintering instructions are the same as for the Japanese Iris.

Ipomoea batatas ‘Blackie’ – Black Sweet Potato Vine, is an annual commonly sold for mixed containers and window boxes. A relative of Ipomoea aquatica – Water Spinach, Sweet Potato Vine lends a colorful accent , with deep purple, arrowhead-shaped leaves. Best at the water’s edge, with water at the soil level or just below, it will trail onto the water surface and scramble up the pond edge, softening the lines. If koi or goldfish inhabit the pond, this is one plant that they don’t seem to enjoy munching on – and the natural ‘fertilizer’ they provide results in much larger leaves than usually found on this plant. Other interesting varieties include ‘Marguerita,’ and ‘Terrace Lime’ with brilliant chartreuse leaves, and ‘Tricolor,’ with cream, green and violet mottled leaves. All three provide a tropical aura at pond’s edge.

Another plant with jewel-toned foliage is commonly used as a groundcover in shade gardens. Chameleon Plant, Houttuynia cordata ‘Chameleon,’ has up to three inch, heart-shaped leaves splashed with red, yellow, green and cream. Small, white flowers appear in early summer. Houttuynia grows well in average garden soil, as well as in the pond with up to two inches of water over the crown. With a height of twelve inches, it makes a fine companion planting with Carex nigra - Black Flowering Sedge, or Carex elata ‘Bowles Golden’ – Yellow Sedge.

There are a few shrubs and small, multi-stemmed trees that add height, screening, and texture to the pond and surrounding area. The Buttonbush – Cepalanthus occidentalis, requires constantly moist soil, and really thrives in wet conditions. It features glossy, bright green foliage and showy, creamy-white pompon flowers in July and August. Plant in full sun to light shade, and this four to six foot shrub will be a standout at water’s edge.

There are several members of the willow family that are ideally suited to pond margins. Salix discolor, or Pussywillow, is an early spring favorite, with pink-tinged fuzzy catkins. The green leaves have silver undersides, and contrast nicely with the dark brown bark. It grows twelve to fifteen feet tall, and prefers full sun to light shade in constantly moist soil. The Black Pussy Willow, Salix gracilostyla ‘Melanostachys’ is much smaller at six to eight feet, with dark green catkins that appear black against the lighter colored twigs. In the winter, the bark becomes a deep red, providing visual interest at a time when most ponds show no color. Black Pussy Willow performs best in full sun. Salix ‘Golden Curls,’ a variety of curly willow, is a small, shrubby tree with golden, spirally twisted branches. It performs well in full sun to light shade, and grows to thirty feet. The contorted branches provide visual interest in all four seasons.

Many other garden plants can be used as aquatic marginals – check the cultural instructions, and look for soil moisture requirements using the words "constantly moist," "wet," or "boggy" - then, feel free to experiment!

Date: JUNE 5, 2000
Author: Lisa Calvo Goering