This rain garden used stone for a berm and muhly grass as a decorative and functional plant. Photo credit, Jerry Patee
Tropical Storm Cindy’s early arrival soaked northwest Florida this month, followed by even more heavy rain. Homes in low areas and along the rivers flooded and suffered extensive damage. That being said, we are just entering our summer “rainy season,” so it may be wise to spend extra time thinking about adjusting your landscape to handle our typically heavy annual rainfall.
For example, if you have an area in your yard where water always runs after a storm (even a mild one) and washes out your property, you may want to consider a rain garden for that spot. Rain gardens are designed to temporarily hold rainwater and allow it to soak into the ground. However, they are quite different aesthetically from stormwater ponds, because they are planted with water-tolerant trees, shrubs, groundcovers and flowers to provide an attractive alternative to the eroding gully that once inhabited the area! Rain gardens are not “created wetlands,” but landscaped beds that can handle both wet and drier conditions. Many of the plants best suited for rain gardens are also attractive to wildlife, adding another element of beauty to the landscape.
A perfect spot for a rain garden might be downhill from a rain gutter, an area notorious for excess water and erosion. To build a rain garden, the rainwater leaving a particular part of the property (or rooftop), is directed into a gently sloping, 4”-8” deep depression in the ground, the back and sides of which are supported by a berm of earth. The rain garden serves as a catch basin for the water and is usually shaped like a semi-circle. The width of the rain garden depends on the slope and particular site conditions in each yard. Within the area, native plants are placed into loose, sandy soil and mulched. Care should be taken to prevent the garden from having a very deep end where water pools, rather allowing water to spread evenly throughout the basin.
This larger rain garden, or bioretention area, functions as stormwater treatment for a large parking lot in North Carolina. Photo credit: Carrie Stevenson, UF / IFAS Extension
Besides reducing a problematic area of the lawn, a rain garden can play an important role in improving water quality. With increasing populations come more pavement, roads, and rooftops, which do almost nothing to absorb or treat stormwater, contributing to the problem. Vegetation and soil do a much better job at handling stormwater. Excess sediment, which can fill in streams and bays, and chemicals from fertilizers and pesticides are just some of the pollutants treated within a rain garden via the natural growth processes of the plants.
A handful of well-known plants that work great in rain gardens include: Louisiana iris, cinnamon fern, buttonbush, Virginia willow, black-eyed Susan, swamp lily, tulip poplar, oakleaf hydrangea, wax myrtle, Florida azalea, river birch, holly, and Southern magnolia. For a complete list of rain garden plants appropriate for our area, visit the “Rain Garden” section of Tallahassee’s “Think about Personal Pollution” website.
For design specifications on building a rain garden, visit the UF Green Building site or contact your local UF IFAS County Extension office.
Saltbush seed in “bloom” stands out in a salt marsh dominated by black needlerush. Photo credit: Zach Schang, FDEP
In the spring and summer, no one notices the little green shrub hidden among wax myrtle and marsh elder at the edge of the salt marsh. However, if I’m leading a group of students or a Master Naturalist class through the same area in the fall, it’s the first plant people ask about. The saltbush or groundsel tree (Baccharis halmifolia) blooms dramatically in late September and October, with feathery, dandelion-like white “flowers” on female plants. These seeds are dispersed far and wide by the wind. Male plants typically grow side-by-side with females, and produce yellowish, tubular blooms at the same time. Characterized as both a large shrub and a small tree, the saltbush typically branches from multiple trunks and ranges in height from 2-10 feet. The leaves are rough to the touch and slightly succulent, enabling the plant to hold onto moisture in the sandy, hot environments on the uphill edges of wetlands in which it thrives.
The leaf of Baccharis angustifolia is narrower than B. halmifolia. Both are succulent, enabling the plants to hold on to moisture in a salty environment. Photo courtesy Shirley Denton, Florida Plant Atlas.
The leaf of Baccharis halmifolia is lobed and wider than B. angustifolia is narrower. Both are succulent, enabling the plants to hold on to moisture in a salty environment. Photo courtesy Forestry Images.
The plant is often confused with its near relative, false willow (Baccharis angustifolia), which is typically co-located with saltbush in coastal wetlands. It also blooms white in the fall, but can be differentiated by its slender, almost needle-like (but also succulent) leaves.
Saltbush is not typically used in the home landscape, as some people are allergic and the seeds are poisonous if ingested. Properly planted, however, it is a perfect addition to a butterfly garden because the male plants’ fall flowers provide nectar to numerous butterfly species, including the monarch. Another ideal location for saltbush would be a rain garden or the edges of a stormwater pond. Coastal property owners on the bay or Gulf would find it an excellent addition due to its tolerance of the year-round salt spray. The species is very hardy–tolerant of both wet and dry soils–along with a variety of soil pH levels. Plant saltbush in full sun with at least 3-5 feet between young plants.
For additional information on the characteristics of saltbush, please see the UF publication, Baccharis halmifolia Saltbush, Groundsel Bush and check out this entertaining video from our Lee County colleague, Stephen Brown, as he immerses himself in a stand of saltbush.
Rain gardens are an easy way to return water to our aquifer, reduce erosion, and help prevent stormwater runoff.
Running down the driveway or patio, rainwater can pick up lawn chemicals and pesticides. A rain garden is basically a low section of the landscape planted with native plants that like to get their “feet” wet. The garden collects rainwater, giving it a chance to “strain” out impurities before draining into the aquifer.
Swamp sunflower. Photo courtesy UF/IFAS.
They work best when they’re placed at the bottom of downspouts or naturally low spots in the landscape, usually where water tends to puddle. They’re especially useful for collecting runoff from paved surfaces. Rain gardens can be any size or shape and can attract thirsty wildlife.
When selecting plants, you’ll need to consider how much sun your site gets and how much space is available. Make sure you select plants that are not just water-tolerant, but also drought-tolerant for the times between rains.
Rain gardens rely on plants that will survive dry spells but then soak up excess stormwater during Florida’s rainy months, preventing the water from running across your landscape.
Blue flag iris. Photo courtesy UF/IFAS.
Include different types of plants in your rain garden to create a complete and cohesive look that will provide year-round interest. The following is a short list of flowers, shrubs, and grasses that would perform well in a rain garden.
Flowers:
Blue flag iris
Goldenrod
Swamp sunflower
Spider lily
Milkweed
Grasses:
Florida gamma grass
Muhly grass
Wiregrass
Shrubs:
Virginia willow
Buttonbush
Wax myrtle
Here is a list of native plants that will do well in your North Florida rain garden. As always consult your local Extension Office for more information. All of the information in this article was provided by UF/IFAS Extension.
Rain gardens can make a beautiful addition to a home landscape. Photo courtesy UF IFAS
Northwest Florida experienced record-setting floods this spring, and many landscapes, roads, and buildings suffered serious damage due to the sheer force of water moving downhill. That being said, we are just entering our summer “rainy season,” so it may be wise to spend extra time thinking about how you want to landscape based on our typically heavy annual rainfall. For example, if you have an area in your yard where water always runs after a storm (even a mild one) and washes out your property, you may want to consider a rain garden for that spot.
Rain gardens work similarly to swales and stormwater retention ponds in that they are designed to temporarily hold rainwater and allow it to soak into the ground. However, they are quite different aesthetically, because they are planted with water-tolerant trees, shrubs, groundcovers and flowers to provide an attractive alternative to the eroding gully that once inhabited the area! Rain gardens are not “created wetlands,” but landscaped beds that can handle both wet and drier soil. Many of the plants best suited for rain gardens are also attractive to wildlife, adding another element of beauty to the landscape.
This diagram shows how a rain garden works in a home landscape. Photo courtesy NRCS
A perfect spot for a rain garden might be downhill from a rain gutter, areas notorious for excess water and erosion. To build a rain garden, the rainwater leaving a particular part of the property (or rooftop), is directed into a gently sloping, 4”-8” deep depression in the ground, the back and sides of which are supported by a berm of earth. The rain garden serves as a catch basin for the water and is usually shaped like a semi-circle. The width of the rain garden depends on the slope and particular site conditions in each yard. Within the area, native plants are placed into loose, sandy soil and mulched. Care should be taken to prevent the garden from having a very deep end where water pools, rather allowing water to spread evenly throughout the basin.
Besides reducing a problematic area of the lawn, a rain garden can play an important role in improving water quality. With increasing populations come more pavement, roads, and rooftops, which do almost nothing to absorb or treat stormwater, contributing to the problem. Vegetation and soil do a much better job at handling that water. Excess sediment, which can fill in streams and bays, and chemicals from fertilizers and pesticides are just some of the pollutants treated within a rain garden via the natural growth processes of the plants. Many commercial properties are considering rain gardens, also known as “bioretention” as more attractive alternatives to stormwater retention ponds.
The North Carolina Arboretum used a planted bioretention area to manage stormwater in their parking lot. Photo courtesy Carrie Stevenson
A handful of well-known perennial plants that work great in rain gardens include: Louisiana iris, cinnamon fern, buttonbush, Virginia willow, black-eyed Susan, swamp lily, tulip poplar, oakleaf hydrangea, wax myrtle, Florida azalea, river birch, holly, and Southern magnolia. For a complete list of rain garden plants appropriate for our area, visit the “Rain Garden” section of Tallahassee’s “Think about Personal Pollution” website, tappwater.org or contact your local Extension Office.
