Curbside plantings that filter the pollutants of the street
Story by Rachel Williams
Natural chi flows to our homes right at its start – the curb! Unfortunately so does pollution. An easily dismissed aspect of this is noise pollution, which we can never totally drown out. Constant noise has many negative impacts, including hearing loss, insomnia, and anxiety. Your curb is a great place to start reducing that sound.
Another pollutant knocking at our door is car exhaust, which is actually a combination of the pollutants soot, hydrocarbons, sulfur oxides, nitrogen oxides, carbon monoxide, and carbon dioxide. Other contaminants include lead, fluoride, and fly ash as well as spray from mosquito trucks or road salts, all of which can have negative affects on our ecosystem. They can impair breathing and even make it difficult for our plants to photosynthesize (convert light to energy … and provide us with oxygen).
Plants are our proverbial canaries in the coal mine, and according to HealthGuidance.org, they will likely be used for this purpose in the future, like using forest species around certain industries to act as early warning systems of toxic emissions since plants show signs of biologically significant exposure before humans, react to a number of pollutants, and are cheaper than specialized instrumentation.
Plants show symptoms such as lesions, yellowing, and irregular blotches between the veins of leaves. Injured tissue may appear white or gray, with larger veins remaining green. On grasses, injury appears as streaks and general blight on leaf tips. Signs include collapse of tissue and silvering, glazing, or bronzing, and death of leaf margins and tips.
But believe it or not, pollutants can be limited solely by contact with leaves. Microorganisms in soil also reduce air pollutants and degrade many toxic chemicals that enter the soil. Plants also hold topsoil in place (reducing sediment and preventing excess nutrients from polluting water).
Maintaining an abundance of vegetation can help reduce the amount of pollutants that reach our homes and attention to curbside plantings is an overlooked method of filtering.
Some areas (not Alabama – yet), offer monetary incentives for nature-friendly landscapes. This includes clean water projects such as rain gardens. These can limit the amount of pollution that reaches creeks and streams, as well as reduce soil erosion, flooding, and the need for fertilizer. A rain garden is a great option if you have a concave area near your curb. It will absorb water runoff from roofs, driveways, walkways, lawns, etc. It catches the water, allowing it to percolate into the soil rather than allowing it to contaminate local waterways. In addition to absorbing rainwater, rain gardens can also capture water from basement sump-pumps, gutter drain spouts, and more.
Rock gardening is a popular landscape style that minimizes erosion. If you’re starting with grass, dig it up or cover it with paper or cardboard (anything that doesn’t have a coating or sheen to it) and then create a base layer of rock and soil. Place your larger rocks first and then fill the area in with sandy soil mixed with compost. Then place your most attractive rocks. Use plants that require good drainage. Select your theme and plant in odd-numbered groupings, placing additional small rocks along the way. Cover the remaining surface with stone mulch.
The color of your house should be a consideration when choosing plants for any landscape style. If a garden seems out of place, look to the house for color clashing. Calm colors are accented by calm colors and warm by warm (blue by purple and white; red by orange and yellow).
Fences are great for establishing boundaries and look great when covered with vines. If you have ability and really want to get your hands dirty, consider building papercrete or adobe walls. These can also be used to espalier plants such as Pyracantha or ‘St. Mary’ southern magnolia (M. grandiflora ‘St. Mary’, sometimes called ‘Glen St. Mary’).
Ground covers are another great option for curbside plantings. Space small ground covers 6-24 inches apart. Consider Japanese spurge (Pachysandra terminalis), or creeping St. John’s wort (Hypericum calycinum). Easy shrub covers are lavender cotton (Santolina chamaecyparissus), Cotoneaster, and Japanese garden juniper (Juniperus procumbens).
Plants selected for your curb area would ideally be native and able to tolerate both saturated and dry soil. If you like the idea of wildflowers, but want to avoid the city weedwacking your beauties down to bare dirt, consider Arkansas blue star (Amsonia hubrichtii), blue fescue (Festuca glauca), blue wild indigo (Baptisia australis), English lavender (Lavandula angustifolia), New Zealand flax (Phormium tenax), prairie dropseed (Sporobolus heterolepis), or purple coneflower (Echinacea purpurea).
Depending on how eclectic your neighborhood is, accent your entrance in an interesting way, like perhaps using an old wheelbarrow as a planter, shutters for a gate, wrought-iron archway, or using stencils to liven up brick.
Any plant that has a striking form, interesting texture, or bright foliage such as Hosta, bearded iris (Iris germanica), Nippon lily (Rohdea japonica), variegated Liriope, Caladium, sago palm (Cycas revoluta), curve-leaf yucca (Y. recurvifolia), century plant (Agave americana), or Adam’s needle yucca (Y. filamentosa) is great for breaking up the monotony of a mass planting.
And remember: The safety of drivers and pedestrians should always be the first and most important consideration of any curbside planting.
Great options for curbside trees and shrubs
Parsons juniper (Juniperus davurica ‘Parsoni’)
Dwarf yaupon (Ilex vomitoria ‘Nana’)
Indian hawthorn (Rhaphiolepis spp.)
Rockspray (Cotoneaster horizontalis)
Mugo pine (Pinus mugo)
Pfitzer juniper (J. x pfitzeriana)
‘Mint Julep’ juniper (J. x pfitzeriana ‘Mint Julep’)
Russian sage (Perovskia atriplicifolia)
Upright, narrow shrubs:
Hollywood juniper (J. chinensis ‘Kaizuka’)
Yew or Buddhist pine (Podocarpus macrophyllus)
Spicebush (Lindera benzoin)
Large shrubs/small trees:
‘Dwarf Burford’ holly (Ilex cornuta ‘Dwarf Burford’)
Yaupon holly (I. vomitoria)
Sassafras tree (S. albidum)
Armstrong juniper (J. x pfitzeriana ‘Armstrongii’)
False cypress (Chamaecyparis pisifera)
Japanese black pine (Pinus thunbergii)
Japanese yew (Taxus cuspidata)
Wax myrtle (Morella cerifera)
Sweet viburnum (V. odoratissimum)
Southern Indian azaleas (Rhododendron indicum)
Narrow upright trees:
Slash pine (P. elliottii)
Lombardy poplar (Populus nigra ‘Italica’)
Italian cypress (Cupressus sempervirens)