Places in the landscape that hold standing water create a problem for the homeowner, because standing water can harbor mosquitoes that spread disease. Also, areas of standing water are difficult to mow and maintain--so planting plants that absorb standing water is a way to solve the problem of standing water in the landscape.
Iris grows thickly, spreads by rhizomes, and most varieties produce colorful blooms several times during the summer. The best varieties for growing in low lying and wet areas are Louisiana iris, German iris and Japanese iris.
Elephant ear (Colocasia) provides a tropical look with its big green leaves. Elephant ears naturalize over the years and are a good plant to use for soaking up water. Elephant ears will freeze back to the ground in freezing weather but will return from the large bulb when the weather warms in late spring. Look for an upright variety such as "Jack's giant" or "Midnight" for the best show in the garden.
Coreopsis (Coreopsis tripteris) are a native perennial wildflower that spread rapidly. They have a bright yellow or red single or double flower depending on the variety in spring. They decline in mid- to late-summer after the blooming period. They are good to plant with something that is slower to produce foliage or flowers, such as ferns or other wildflowers that do well in wet areas--such as the obedient plant (Physostegia virginiana).
Daylilies are an old-fashioned plant with many varieties passed down through generations. The trumpet-like flowers are produced in yellow, red, or orange or a combination thereof. Double blooming varieties are available. The individual plants are usually inexpensive and naturalize freely. This is one of the best plants for planting in a wet area if provided full sun.
The obedient plant (Physostegia virginiana) is a native wildflower that naturalizes in wet areas and blooms all summer. It has white or pink spiked flowers and grows to 3 feet tall. It's known as false dragonhead. Obedient plant spreads aggressively and the area it covers will double in size every year as long as enough moisture is provided.