Six on Saturday: Rain Gardens

Both Caladiums and most ferns appreciate moist soil and can survive for quite a while in saturated soil. Ferns planted in wide strips as ground cover can slow down and absorb run-off from summer storms.


It’s still raining here.  It has been raining off and on for days, but mostly on.  We’re under a multi-day flood watch and a flash flood advisory.   A tropical storm inundated us not long ago and another formed off of our coast yesterday, and even heading out to sea it pulls historic rains behind as it moves away.

The ground is already saturated and every little plastic saucer under a ceramic container overflows.  I smile at the thought of how long it will be before I’ll need to water the garden again.  August usually is a wet month, and welcome after hot, dry stretches in July.  But the tropical storm season forecast for 2020 is unlike anything we’ve ever known before.  (That is our new catch phrase for 2020, isn’t it?  Unlike anything we’ve ever known before?)


Scarlet cardinal flower, Lobelia cardinalis, is a classic rain garden plant. It thrives in moist soil but will survive short droughts, too.  This clump grows in the wetlands area of the Williamsburg Botanical Garden.


We have a program in our county that helps homeowners install rain gardens.  A friend is known for her beautiful rain garden designs. When working with local government and the Master Gardeners, county residents can have significant portions of their costs reimbursed.

The idea is very simple and elegant:  Rain gardens are dug a few inches below grade to catch and hold run-off from heavy rains.  Water loving plants growing in the rain garden help soak up the run-off, even as it settles into the ground to replenish the water table, instead of running off into local waterways, and eventually the Chesapeake Bay.  Unlike ponds, they don’t hold standing water indefinitely.  Most absorb and process the run-off soon after a rain.

Rain gardens help catch pollutants that wash off of lawns and streets so those nutrients and chemicals can be recycled and trapped by vegetation.  This helps reduce the amount of pollution flowing into creeks, the rivers, and eventually the Chesapeake Bay.  They also provide habitat for small animals like turtles, toads, frogs, dragonflies and many types of birds.

Even when we don’t excavate and engineer a formal rain garden, there are things we can do to help slow the flow of water across our yards and capture a portion of that rain water before it flows into the local waterways.  We’ve built a number of terraces in the steepest part of our yard and planted them with plants to help slow the flow of rain water.  We also have several ‘borders’ of shrubs and other vegetation to break the flow of run-off and absorb it.

In fact, the slogan of our county Stormwater and Resource Protection Division is, “Plant More Plants.”   Plants buffer the falling rain, help protect the soil from erosion, slow run-off and absorb large quantities of water, returning it to the atmosphere.  Just planting trees, shrubs, ground covers and perennial borders helps to manage the abundant rain we are getting in recent years.


Zantedeschia, or calla lily, thrives in moist soil.  Some species will grow in the edge of a pond, and these work very well in rain gardens or wet spots where run-off collects.


But when the ground is as saturated as it is today, we worry that even some of our plants might drown!  You see, most plants’ roots want air pockets in the soil.  Saturated soil is a quick way to kill a houseplant, and it can cause damage to the roots of some trees, shrubs and perennials, too.

As our climate shifts and these rain soaked days grow more common, it helps to know which plants can take a few days of saturated soil, and maybe even benefit from the extra water in the soil.  Many of these plants process a great deal of water up through their roots and vascular systems to release it back into the air.

You have heard of the Blue Ridge Mountains in western Virginia?  Well, that blue haze comes from moisture released by the many trees and shrubs growing on the sides of the mountains.  Some trees thrive in constantly moist soil.  Try birches, willows, swamp dogwoods, white ash trees, and beautyberry bushes.

Plants release both water vapor and oxygen back into the air as a by-product of their life processes.  Some plants, like succulents, release very little water, and that mostly at night.  They will quickly die in saturated soil.  In our region they need to be planted higher than grade on ridges and mounds, or be grow in freely draining containers.


Colocasia and some types of  Iris grow well in saturated soil or even standing water.   Abundant water allows for lush growth.


Plants with very large leaves, like our Caladiums, Colocasias, Hibiscus, Alocasias, Calla lilies, Canna lilies, ginger lilies, and banana trees use large amounts of water and release water vapor from their leaves throughout the day.  Some types of Iris also perform very well in saturated soil.  They can live in drier soil, but do just fine planted in the edge of a pond or in a rain garden.  Ferns are always a classic choice for moist and shady areas of the garden.  Their fibrous roots help to hold the soil against erosion and perform well as ground cover on slopes.

Those of us living in coastal areas where flooding has become more frequent can use plants to help deal with the inches and inches of extra rain.  We can build ponds and rain gardens, or even French drains and rock lined dry gullies to channel the run-off away from our homes.

We are called on in these times to wake up, pay attention, and find creative and beautiful solutions to the challenges we face.  We are a resilient people, by taking every advantage, even in the choices of plants we make, we can adapt to our changing world.


Iris ensata, Japanese Iris,  grow with Zantedeschia in the ‘wet’ end of the Iris border at the Williamsburg Botanical Garden. Clumps keep their foliage most of the year, blooming over a long season in late spring and early summer.  These are excellent rain garden and pond plants.


Woodland Gnome 2020


Visit Illuminations, for a daily quotation and a photo of something beautiful.

Many thanks to the wonderful ‘Six on Saturday’ meme sponsored by The Propagator

About woodlandgnome

Lifelong teacher and gardener.

4 responses to “Six on Saturday: Rain Gardens

  1. An electrical storm just went over just past midnight this morning. Such storms are very rare here. Rain drops were big, but scant. It was weird. There was not enough moisture to extinguish the fires that the lightning started.
    Anyway, this is unrelated, but I just acquired an old book, ‘A Window On Williamsburg’ from 1966, when Williamsburg was a tourist destination that my parents visited. I had never been away from the West Coast, but learned about horticulture of the East, particularly between North Carolina and Pennsylvania, as well as Oklahoma. It is fascinating to find the book now.

  2. I’m sad we didn’t get some of that rain. We are so dry. Most of the storm is passing a couple hours to our east.

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