Published on 02/24/97

Winter Rains Can Sink Perennial Beds

Recent wet winter weather reminds us of why good drainage is important for healthy perennial beds.

"As long as the water is moving off of the bed, you don't have problems with wet weather," said Gary Wade, a University of Georgia Extension Service horticulturist. "When the water is standing in the bed, you have big problems."

To avoid those critical pockets of standing water, start with a good drainage system.

"If you have water problems now, there isn't much you can do, short of ripping out your perennials and starting over," Wade said. "You have to create a good drainage system from the beginning."

He recommends tilling as deeply as possible to break up any hardpan that lays beneath your beds.

"You can also raise beds four to six inches above the grade," he said. That will not only allow the bed to drain better but will help people see the color display better, too.

If you don't know if your bed has poor drainage, try a simple perk test.

"Just dig a hole in the bed and fill it with water," Wade said. "Come back 24 hours later, and if the hole still has water in it, you have poorly drained soil."

If you have bad drainage, about the only relief you can offer your beds is to carry the water off the site.

Wade warns against adding sand to Georgia's clay-laden soils in an attempt to increase drainage. "You can create cement," he said. "That would be detrimental."

Instead, Wade recommends bringing in good topsoil.

While Georgia seems to have had an abundance of rain this winter, he said, it's actually normal February weather.

"We have to remember that most perennials have very shallow, fibrous root systems," he said. "So those that are hurting now are those in badly drained beds that allow water to stand and suffocate the root systems."

Wade said some perennials such as Siberian and Japanese iris, hosta, liatris, lobelia, astilbe, phlox, monarda and physostegia are very tolerant of moist sites and can survive wet periods without a scratch. Yellow flag iris, he said, will grow in standing water and is often used in pondscapes.

Some homeowners try to help their beds' drainage by removing their mulch.

"That does more harm than good," Wade said. "If you remove the mulch, you're exposing the roots. When we get a few sunny days, the roots will be damaged by the drying effect of the sun. Just leave your mulch in place and cross your fingers that we don't get much more rain."

Faith Peppers is the director of public affairs with the University of Georgia College of Agricultural and Environmental Sciences.