Gardening in Colorado is filled with challenges and opportunities — perhaps no more so than in the summer growing season with variable temperatures and rainfall.
Plant selection plays an important role in gardening success, and plants that add variety and can be forgiving of periodic neglect can contribute significantly to this success.
Succulents which include agaves, sempervivums, cacti, sedums and ice plants are classified as xeriphytic or drought resistant. Most store water in leaves, roots or stems following moisture events which enables them to survive periods with no or limited moisture. While the term “succulent” may conjure the image of a cactus in a sandy, hot, dessert climate, the diversity of plant material within this broad grouping lends well to incorporation into many aspects of the Colorado garden.
For a statement or to add a textural element to the garden consider an agave, yucca or cactus. The agave and cacti with their natural spines can also serve a dual role as a protective element, but likely should be avoided in a yard where children or pets play. All have interesting hues and shapes to complement or set-off other plants in the garden and provide structural interest in the winter.
An added benefit is that wildlife tends to stay away from these plants. Many succulents also make excellent, low maintenance (once established) containers/hypertufas, rooftop or upright garden plantings and may be used to make colorful natural mosaics as an accent in the yard.
For a dramatic focal point in a protected, ideally southern or western-facing, area of the garden, a slow growing, tree yucca such as Yucca faxonia, Y. thomsponiana, Y. elata or Y. rostrata could be considered. Many shrub forms of yucca have better cold hardiness (as compared to the tree forms) and offer not only different options for leaf color and texture, buy will also put out a showy flower stalk.
Yucca glauca, Y. flaccida and Y. baccata are among the many options available. The hesperaloe (i.e. Hesperaloe parviflora) are not true yuccas, but fall within the same family and are reliable flowering plants that are easily incorporated into a xeric perennial garden.
Agave with their uniquely symmetrical rosette shape may also be used as a focal point but remember they have spines at the tips and all along the leaves; if embedded in the skin these can be difficult to remove (use duct tape if this happens). Agave may take years to flower and when they do, the flower producing plant or rosette dies, but off shoots ensure continued plant viability.
While there are other options, Agave neomexicana is touted among the hardiest selection for our area.
Cacti in addition to their form and ability to reflect light can also put on a great flower show in the spring. Most people are familiar with the prickly pear cacti or opuntia, which there are hardy varieties (eg. Opuntia polyacantha) to choose from, some of which are considered prolific bloomers (eg. Opuntia humifusa).
Chollas are another form of cacti with a cylindrical form (as opposed to the rounder flatter form of the opuntia) and offer additional diversity in size, shape and flower. Spines on cholla cacti can be particularly vicious.
If spiny plants don’t work for your landscape, do not despair as there are many other succulent options. Their growing use and popularity is reflected through and increasing number of named Plant Select varieties (eg. Red Mountain and Table Mountain ice plant and Turquoise Tails blue sedum) with documented success for Colorado gardens.
Within the sedums there are many varieties and shapes which add texture and color. Sedum rupestre “Angelina” is one such plant with glowing yellow tips on bright green succulent foliage. It may be used in containers or as a ground cover well suited to hot, dry, neglected areas of the yard.
If you prefer reddish or variegated foliage, try Sedum spurium “Voodoo” or Sedum spurium “Tricolor.” Sedums are unique for succulents as some do well in shade, such as the trailing Sedum sieboldii “Mediovriegatum.” Sedums also come in upright varieties, probably the most notable of which is Sedum “Autumn Joy” which, as the name suggests, flowers in autumn. Upright sedums with dark purple, variegated foliage and variations of yellow are also available.
Another option for ground covers and one that is well suited to plantings with spring bulbs are the delospermas or ice plants. They are generally low growing, variably spreading and frequently flower from spring throughout the hot summer months.
While they may be used in pathway plantings, they can overgrow these small spaces quickly and can be slippery if walked on. Delosperma “Kelaidis” is named for Panyoti Kelaidis, who many will know as a great plantsman from our area and the senior curator of the Denver Botanic gardens.
The third non-thorny option is the sempervivums, known commonly as hens and chicks due to their tendency to expand via small rosettes of the main plant. These tend to spread more slowly (plants with larger rosettes will spread quicker than those with smaller ones) but lend themselves well to creating different patterns within a container or garden space. Some will put on a showing of upright flowers in summer. An example is Sempervivum “Sugaree,” whose flowers have a pinkish hue. They also offer different variations in foliage, such as red-tipped S. apache or pinkish-tipped “Beatrice.”
Once you have selected your plants remember that the two most important environmental are sunlight and good drainage. Sandy or gravelly soils are desirable for most succulents, and are especially important if there is a potential for heavy rainfall — succulents do not like “wet feet.” If incorporating plants into a garden, siting these plants on a mound or with other plants of like water requirements is ideal. Southern, sloping exposures increase radiant heat. Plants in this group will do well despite the intense light, but may need additional winter protection. ❖