Richard Bogren | 5/11/2017 6:27:07 PM
By Dan Gill
LSU AgCenter Horticulturist
(05/12/17) Homeowners are frequently faced with areas of their landscapes that present special challenges. Problem areas may be low and wet and stay damp much of the time, heavily shaded under tree canopies, or hot and sunny.
The common inclination is to try to change the area to make it easier to be successful with the plants you want to grow there. You may consider spreading fill or creating raised beds, for example, so you can grow plants that need good drainage in a spot that tend to stay wet. Or you may install an irrigation system to water a dry area. But transforming of an area generally involves considerable cost and effort.
A lot of the stress and effort involved in gardening can be reduced by learning to cooperate with existing natural conditions. Work with them instead of altering or changing them. Choose plants that are adapted to the type of soil pH and texture (sandy or clay) you have. For areas that are damp, soggy, shady or hot and dry, select plants that prefer those conditions rather than changing the situation.
Here are several conditions and suggestions to accommodate them:
Rain gardens are a great way to take advantage of low, damp areas. They hold water on site and allow it to filter into the soil rather than run off into the street. It’s a way homeowners can help deal with runoff water after rains.
To construct a rain garden, identify a low area that stays wet for extended periods after a heavy rain. Most rain gardens are natural, so mark off an area with an informal shape rather than a perfect rectangle or circle. Remove the sod and soil down about 6 to 8 inches to create a catch basin that will hold water. Till the soil at the bottom of the rain garden and incorporate an inch or two of organic matter that will encourage the plants to grow well.
A wide variety of native plants enjoy wet soils and will also tolerate dry periods between rains.
Shady areas should not be a problem, but they often are. Once trees get large and cast substantial shade, it’s difficult to impossible to get lawn grass to grow. Yet many people still try and lay sod repeatedly. Sometimes, landscape plants that prefer sun are planted in shady areas and fail to thrive.
The solution to this is not difficult: Choose plants that will thrive in the light conditions where they are planted. If you have a shady area, go directly to the shade-loving plant section of the nursery to make your selections. If lawn grass will not grow in an area that has become shady, replace it with mulch or ground covers.
Dry shade often occurs under large trees that absorb much of the water in the soil under their canopy. If you have dry shade, you can grow any shade plant with adequate watering. But constant watering is a no-win attempt to change the natural conditions to suit the plants. Instead, choose plants that will thrive in the dry, shady conditions without a lot of irrigation.
Several excellent plants will grow in dry shade. If the tree you are planting under is deciduous, you can plant spring-flowering bulbs like paperwhite narcissus, snowflakes, Spanish bluebells, Dutch iris and Peruvian scilla. During winter when they grow, these plants will receive plenty of sun and rain to keep them happy. During summer when they are dormant, they prefer to be dry, and the shade is not an issue.
Sunny, dry areas
Hot, sunny, dry areas can also be challenging, but some plants will grow well in these locations with little care. As always, supplemental irrigation the first year will be needed while the plants are sending out roots into the surrounding soil and getting established. Mulching beds in these areas is beneficial. Mulch will help hold moisture in the soil and keep the soil cooler in summer, which benefits the roots.
Plants for rain gardens or wet areas include:
Trees: parsley hawthorn (Crataegus marshallii), wax myrtle (Morella cerifera), yaupon holly (Ilex vomitoria). Shrubs: American beautyberry (Callicarpa americana), Virginia willow (Itea virginica), dwarf palmetto (Sabal minor). Perennials: swamp milkweed (Asclepias incarnata), cardinal flower (Lobelia cardinalis), mallow or hardy hibiscus (Hibiscus moscheutos and hybrids), Louisiana iris (Iris species and hybrids), swamp sunflower (Helianthus angustifolius). Non-natives: canna, elephant ear, calla lily (Zantedeschia aethiopica).
Plants for dry shady areas include:
Aspidistra or cast iron plant (Aspidistra elatior), Manfreda (a relatively new group of garden plants), jewels of Opar (Talinum paniculatum), hellebore (Helleborus orientalis), liriope (Liriope muscari), monkey grass or mondo grass (Ophiopogon japonicus).
Plants for dry, sunny areas include:
Color Guard yucca (Yucca filamentosa Color Guard), red hot poker (Kniphofia), yarrow (Achillea millefolium), red yucca (Hesperaloe parviflora), agave (Agave), junipers (Juniperus many different cultivars), Texas sage (Leucophyllum frutescens).
Louisiana irises are among the plants that do well in sunny, wet areas and rain gardens where rainwater accumulates. Photo by Rick Bogren/LSU AgCenter
Yuccas thrive along the sunny side of a fence in a New Orleans yard. Photo by Eric Bogren