DT: Autumn Sage
Salvia greggii is one of the most reliable and easy-to-grow drought-tolerant perennials. There are many varieties of the species available and bloom colors range from pure white to pink, to coral, to deep red. As plants become semi-woody, they are often used as small shrubs in warm climates. Plants can grow approximately 3 feet tall and spread to 5 feet wide. Autumn sage begins blooming in early spring and continues until a hard frost. There are also many S. greggii hybrids with S. microphylla and other species, which are referred to as “Salvia greggii types.” Plant in a sunny location with well-draining soil. Hardiness zone varies by varieties and typically ranges from Zone 5-10.
As a group, Sedums can be relied upon to be sturdy performers in hot and dry landscapes. These hardy succulents are available in assorted sizes, shapes and foliage colors. ‘Blue Spruce’ is a variety particularly good for use as a low-maintenance groundcover along sidewalks, driveways, retaining walls and containers. This variety offers up a unique silvery-blue foliage color. Plants require a full sun location with well-draining soil. Once established, plants require little supplemental water and are highly tolerant of reflected heat. There are sedum varieties available for just about every hardiness zone.
DT: Mexican Feather Grass
Nassella tenuissima, commonly referred to as Mexican feather grass, is a species of grass native in the U.S. only to West Texas and New Mexico. Unlike many other ornamental grasses, this species is compact in size, growing to only 30 inches tall in bloom, in clumps 1 to 2 feet wide. Foliage is threadlike and adds a soft texture to the landscape. The spring and summer inflorescence have a feathery appearance. Plants require a sunny location and well-draining soil, and do not tolerate any excess soil moisture. They are also excellent in containers and cold hardy to USDA Zone 6.
Known as one of the most popular culinary herbs, rosemary also performs as a lush, evergreen landscape shrub or cascading trailer. Plants are drought-hardy once established and very tolerant of intense reflected heat. Can be used in very low-maintenance plantings without supplemental irrigation. Plants bloom sporadically throughout the growing season, but timing will depend on climate. There are many varieties of rosemary available; some grow upright to 6 feet tall, while prostrate varieties will trail over retaining walls and containers. Some varieties are cold hardy to USDA Zone 6, while others are more suited to Zone 8 or higher. Provide a sunny location with well-draining soil.
DT: Bearded Iris
This stunningly beautiful “bulb” also happens to be one of the most reliable drought-tolerant garden plants. The large rhizomes produced by bearded iris plants allow them to not only survive, but thrive under extended periods of drought. Once established, bearded iris do not require supplemental water. However, a bit of supplemental water now and then will result in more flowers. Bearded iris are available in a seemingly unending array of colors, shapes and sizes. There are iris varieties suited for any climate in the U.S. Some perform better in southern soils, while others are more tolerant to cold northern temperatures. Rhizomes should be planted shallowly in loose, well-draining soil in a sunny location. They are hardy to Zones 3-10 in drier parts of the country, 3-8 in wetter parts.
WF: Gooseneck Loosestrife
As with many plants well-suited to a rain garden, Gooseneck Loosestrife, Lysimachia clethroides, can be an aggressive spreader depending on your location. However, if you have room to spare, they make quite an impressive display. Their long racemes of small white flowers curve as they mature, creating a gooseneck-like appearance. Plants establish easily in a rain garden and perform best in moist to wet soils. They don’t tolerate extreme heat or soils that stay dry for extended periods. In cooler climates plants perform well in full sun locations, while they’ll prefer some afternoon shade in southern regions. Each plant creates a clump about 3 feet wide and can be used in mass plantings or mixed borders. Cold hardiness ranges from USDA Zones 3-8.
WF: Yellow Flag
Unlike bearded iris, Iris Pseudacorus is a water-lover. Yellow flag is used to clean waterways as it absorbs heavy metals. Plants can spread aggressively, creating dense clumps of foliage. However, when planted in rain gardens that periodically dry out, their spread will be slowed. Plants produce bright yellow blooms in spring or summer atop sword-like foliage. Plants can tolerate very acidic soils but are also adapted to soil with a high pH. While plants bloom heavier in sunny locations, they will also bloom in shadier locations. Yellow flag can be grown in a variety of conditions throughout USDA Zones 3-9.
WF: Maiden Grass
Some plants have the ability to perform double duty in the landscape by tolerating both drought and wet conditions. Maiden grass, a species in the genus Miscanthus, have that ability. This makes them perfect for use in rain gardens that may experience big swings from very wet to very dry and back again. There are many varieties available that offer up different foliage types, colors and plant sizes. Some varieties of maiden grass, such as ‘Cosmopolitan’ can grow up to 10 feet tall while dwarf varieties such as ‘Adagio’ top out at 3 feet tall. There’s a maiden grass for almost any type or size of landscape space. Plants perform best in a sunny location, but can tolerate some shade. Maiden grasses are typically cold hardy to USDA Zone 4 and are grown through Zone 9.
WF: Calla Lily
While not true lilies, Zantedeschia spp., are very elegant flowers for the spring and summer garden. Plants grow from tubers that are best planted bareroot in the fall. Container specimens can be planted any time in the growing season. Once mature, each tuber will produce a plant that offers up 10-30 flowers. The classic white calla lily is Zantedeschia aethiopica, but there are other species and cultivars in a variety of colors. Callas grow best in consistently moist soils with a sun to part shade exposure. Afternoon shade is recommended in very hot climates. Calla lilies are best suited to warmer climates and are marginally cold hardy to USDA Zone 7.
Spiderwort will brighten up shady spots in rain gardens and along streams and ponds. If there is soggy soil, this plant is bound to thrive. Tradescantia spp. grow in spreading clumps that can spread and seed quickly given the right environment. Choose sterile hybrids for smaller areas or if spreading is a concern. Plants grow to about 2 feet in height. The unique flowers appear in intense shades of purple, violet, pink and even white. Individual blooms last only a day, but are continually replaced by new flowers from spring through summer. Spiderworts are cold hardy to USDA Zone 4 and grown through Zone 9.
Don't forget about turf
While many homeowners are looking to replace lawn areas with drought-tolerant plants or rain gardens, lawns still offer important benefits to the urban dweller and ecosystem. For areas that need to support regular foot traffic and playtime for kids and pets, turfgrass is still a good solution. Lawns can be made more sustainable if the right variety is selected and a proper maintenance regimen is established.
According to Jack Karlin, program director for the Turfgrass Water Conservation Alliance, water-efficient turfgrasses use 30 percent less water than conventional varieties and provide a whole suite of ecological benefits. Dense fibrous root systems nearly double water infiltration rates while high plant density is excellent at securing and protecting topsoil. Turf also sequesters carbon into the soil and produces oxygen at a tremendous rate.
Turf also lowers the ambient temperature of an urban area, helping to mitigate the urban heat island effect, Karlin says.
“Beyond ecological services, turf has been correlated to increased mental and physical wellbeing, especially in children, and provides an affordable, attractive groundcover that enhances any landscape,” he says.
USDA Plant Hardiness Zone Map
The USDA hardiness zone map is the standard by which landscapers can determine which plants will thrive in different locations across the country. The map is based on the average annual minimum winter temperature, divided into 10-degree F zones. Download one at bit.ly/LLusdamap.