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

WPC: Containers II

July 19, 2014 Container 013

When we want to take care of something special, we put it into a special container of some sort.

Michael included an extra plant with the Lemon Lime Hosta he traded with me for some re-blooming German Iris. 

July 19, 2014 Container 007

He send me a beautiful Japanese Iris division.

Yesterday I potted up the Hosta divisions, and they are snuggled safely in a shady spot on the deck while they recover from their Fed-Exed journey in a cardboard box.

The plants as they appeared when I opened the box this morning.  They look healthy and ready to grow!

The plants as they appeared when I opened the box.   They look healthy and ready to grow!

And I decided to start this beautiful Iris division off properly in a container as well.

We have too many hungry voles, and the weather is too variable in summer, to start these  Japanese Iris off in the ground.

Growing perennials in a container is a little trickier than growing annuals.

Although it is easier to move a container around until you find the perfect spot for the right amount of light during the annual cycle of the plant, perennials offer special challenges.

For one thing, most have a fairly short season of bloom.  These Iris for example, bloom once in the spring for a few weeks, and then they rest.

Although their leaves will grow during the summer, storing up energy for spring, they won’t be ready to command “center stage” in a container until next May.

But in the meantime, perennials are heavy feeders.  They grow extensive root systems, and their need for moisture in the soil varies according to whether or not they are in active growth.

So before settling on a planting plan, I went to consult an expert:  Joel Patton of the Homestead Garden Center.

July 19, 2014 Container 003

There I found the perfect deep pot which will accommodate the massive root system perennials grow, and there Joel helped me select appropriate companion plants for the Japanese Iris.

Iris with the other perennials Joel Patton helped me select for this container.

Iris with the other perennials Joel Patton helped me select for this container.

We settled on three: a Salvia, an Artemesia, and an annual Penta; all of which will appreciate the partial sun and moist soil enjoyed by the Iris during a southern summer.

Since there won’t be any Iris flowers during the remainder of the season, I wanted something which would provide flowers in this container garden from now until frost.

The Salvia nemorosa, “New Dimension Blue” is a sturdy bloomer which will keep sending up blue,  bee-satisfying blossoms over the next three months.  A compact grower , this Salvia will bloom happily in partial sun.

These Penta still have small root systems, so I could tuck one into the pot without crowding the other plants.

These Pentas still have small root systems, so I could tuck one into the pot without crowding the other plants.  Pentas attract all nectar loving wildlife.  The Artemesia, to the left, has insignificant blooms.

The annual Penta will also stay in bloom, provide nectar, and will continue to grow taller until taken down by frost in November.  Joel offered these blooming Pentas in a six-pack, so the root ball was quite small.

Finally, this beautiful Artemesia, reduced here at the end of the season, has plenty of light blue foliage to serve as “filler” as the other plants take off.

As the Iris grows in its new leaves, they will become the tall “thriller” in this pot for the remainder of the season.

I purchased the next to the largest pot Homestead had in stock today, to provide plenty of room for growth.

Recycled soil, in the base of the pot, is enriched with a handful of PlantTone to feed the perennials as they grow.

Recycled soil, in the base of the pot, is enriched with a handful of Plant Tone to feed the perennials as they grow.

It is fine to recycle used potting soil in the bottom of large containers such as this.  Potting soil doesn’t really “wear out” over time.  Its nutrients can be replaced easily enough.  The main problem with old potting soil would be the roots of former plants, which should be removed.

I filled the bottom of the container 2/3 full of recycled compost, and then amended it with Plant Tone to provide food, minerals, and beneficial bacteria.

The Homestead Garden Center is a valuable local resource for organic gardeners.  They only offer organic products and use mostly organic methods with the plants they raise in their greenhouse in Lanexa.

The Homestead Garden Center is a valuable local resource for organic gardeners. They only offer organic products and use organic methods with the plants they raise in their greenhouse in Lanexa.

All of the extra rich soil which Michael sent with his Hosta and Iris went into the mix, and then I topped off the pot with fresh, good quality potting mix.

One thing to keep in mind when planting nursery perennials in mid-summer is that these older plants will generally have become root-bound.    Good garden centers, like Homestead, will re-pot their stock into larger containers as the season progresses.

Gently break up the root ball of pot-bound perennials like this Artemesia before planting in fresh compost.

Gently break up the root ball of pot-bound perennials like this Artemesia before planting in fresh compost.

I chose perennials today from their clearance table; those they would rather move out than re-pot again.

So I was careful to loosen and “rough up” the roots a bit before tucking the root balls into their fresh container.  Over the next week or so, these roots will grow into the fresh soil, and will probably fill this container before frost.

This is a “Four Season pot.”

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The only plant I’ll need to replace during the next year should be the Penta.  I’ll switch it out for a Viola in autumn.

I’ll probably tuck a few  Daffodil bulbs into the center of the pot in November, and possibly some Crocus bulbs around the rim for early spring color.

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The bulbs will wake up first, followed by fresh leaves on the Iris and Artemesia.  The Salvia will show new growth by April, just before the Iris comes into bloom.  As the Iris blossoms fade, the Salvia will come into bloom again next spring.

Micheal’s gift Japanese Iris can live in this pot indefinitely.  They will eventually crowd out the other perennials, or will need dividing.

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That is the trade off with perennials:  although they may offer a fairly short season of active bloom, they return again and again, year after year, for so long as their needs are met.

In a Forest Garden like ours, growing special perennials in containers allows them to reach their potential for beauty and growth, which might not otherwise be possible without the controlled conditions a container garden makes possible.

Thank you again, Michael, for these beautiful Iris.  I can’t wait to see them bloom next spring!

July 19, 2014 Container 017

Photos by Woodland Gnome 2014

Weekly Photo Challenge:  Container

WPC: Container I

WPC: Container III





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