Drought resistance is becoming an increasingly important issue in many areas. Increasing shortages and rising costs mean that in drier regions water for gardens may not be available, and in many areas, people want to conserve our precious fresh water supplies. These concerns have produced a whole new style – xeric gardening – which puts the emphasis on plants that don’t need constant watering and that can survive, and even thrive, in drought conditions. Of course, many gardens have hot, dry areas, or sandy soil, so we have always had plants that tolerate drought, it’s just that they are becoming more prominent. Right at the top of any list of xeric plants, and really ideal for any part of the garden that is sunny and dry, are the Sedums, a big group of plants that are very diverse, but that all have one thing in common – they revel in sun and dryness.
We can divide Sedums into two categories. First there are all the ones that crawl and sprawl across the ground, making great ground-cover over rocks and shallow soil, or anywhere that is sunny and dry. These are obvious choices if you have areas like that – and most gardens certainly do. They can be used alone to cover barren areas or planted beneath taller bushes and trees. They wind their way between rocks, and scramble over banks and down slopes. You can even make a natural, drought-resistant ‘lawn’ out of some, and walking on them from time to time won’t do any harm. These spreaders can be used in narrow beds on terraced slopes just as effectively as the can be used in a rock garden, and they look great covering the ground in pots and planters too. Sometimes terraces are built directly on the ground, with gaps between the stones. Crazy paving always has gaps that need filling. Rather than let weeds grow, plant some Sedums in those cracks – they will thrive, filling the spaces with color and interest, and a colorful tapestry effect is easy to achieve.
There is a growing movement towards ‘living roofs’, on buildings of all sizes, and Sedums are perfect for this. They create a green covering over surfaces with virtually no soil and they grow well even in gravel. They can also be planted in vertical walls, and these plants can be used imaginatively to bring life to places where nothing else will grow.
The other group of Sedums are taller, more like small bushes, but they are just as drought-resistant. Plant them as you would shrubs, along the front of beds, or beside a path or driveway. Just as drought resistant, these plants are great way to give some height to dry areas, or pockets with little soil in them. Of course, this division based on size is not absolute, because there are Sedums all the way from flat on the ground to 3 feet tall, but for practical purposes the low growers, with persistent stems that we use as ground cover can be separated from taller, clump-forming ones that re-sprout each year from their base.
Because they are a large, diverse group, it is hard to give a simple description. Although they grow in dry places, they are not ‘cacti’, and have no spines or thorns on them. They are often placed with other similar desert plants as ‘succulents’, a catch-all grouping based on appearance, not relationships.
Most Sedums have stems that trail across the ground, but some grow more upright. The stems are fleshy rather than woody, and some types have stems they survive for years, while others produce new, annual stems from the ground each spring.
The leaves too are variable, but they are almost always fleshy to some degree, with a smooth surface. Some cling closely to the stems, while others grow out in a more normal fashion. They attach directly to the stem, usually without a leaf stalk. Although there are plants that have plain green leaves, most have more colorful leaves, which can be yellow, blue-gray, pink, red or purple. Sometimes an individual plant can have several colors on the leaves, either in different seasons or at the same time. The plants are usually evergreen, but some drop many or all their leaves in winter, leafing out again in spring.
Flowers on Sedums are more uniform. Most grow at the ends of the stems in spring or summer, in clusters of small, star-like flowers with five pointed petals. Most are white, but some are yellow, and pink or red flowers are found too. For some of the larger types the flowers are important garden decoration, while in others they are insignificant, and easily overlooked.
Many Sedums are hardy in zone 3, while others will only grow in milder zones, and some even only in frost-free areas. Because they are so tough, they often regrow from the roots, even if the top growth is killed in winter. When choosing plants, check that they are hardy in your zone – most of the ones sold for outdoor growing are hardy in colder zones, as well as thriving all the way into zone 10.
Sun, and more sun, is the preference of Sedums, although some are tough enough to grow just fine in partial shade. For the best dense growth and leaf colors, as much sun as possible is best, even in the hottest areas.
Soil is almost never an issue when planting Sedums, as they will grow almost anywhere, in the smallest amount of soil. Wetness is the only enemy, and most will quickly perish in wet places. The drier the better for them, and sand and gravel are just fine. Rich soil is not necessary, and most prefer tough conditions – exactly the places that can be such a problem to find plants for.
Although tough, just like any plant the Sedums benefit from a little care when planting. A pocket of slightly better soil in a rocky place, or a sprinkle of soil between paving stones will help them establish themselves. Even a little water from time to time can benefit new plantings, but don’t drown them with kindness.
Since these plants need so little care, there is not much to say here. If plants become untidy, with dead stems, they can usually be trimmed back close to the ground, and they will re-sprout, looking fresh and bright again. This is sometimes necessary to remove dead flower stalks, which can be done by hand on larger plants, or with shears or even a string-trimmer on smaller ones.
Pests and diseases are almost never problems, especially when plants are in plenty of sun and drier soil. Rots and gray-mold can occur when there is too much water, and in very humid conditions a white coating – powdery mildew – may be seen on leaves, but it is harmless and disappears when drier conditions return. Insect pests like mealy-bug or aphids may occasionally be seen, but rarely do any harm.
Deer and rabbits never seem to eat Sedums, so their presence is not a problem when planting, even in wilder places.
There are close to 500 different species of sedum, and some have many garden varieties, but only a few are regularly grown in gardens. They are usually called stonecrop, for obvious reasons, while more fanciful names like frog’s-stomach, Orphan John and witch’s moneybags have also been used. Here are a few of the most widely grown and reliable ones:
Creeping Stonecrop, Sedum spurium – a real garden classic, this low growing plant usually stays 3 or 4 inches tall, and spread out sideways indefinitely, covering a large area and rooting into any soil or cracks as it goes. It is found growing naturally in rocky places in eastern Europe, Armenia, Kurdistan and Iran, and most plants in gardens have been selected for their colorful leaves. The small leaves grow in rows along the stems, and they typically darken in fall and winter.
European Stonecrop, Sedum acre – this tiny but tough plant fills cracks and carpets the ground with a dense covering of stems, just an inch or two tall, wrapped in tiny green leaves. The leaves overlap on the stems like roof shingles. In summer bright yellow flowers rise a few inches above the leaves. It is native to Europe, Northern Africa and Western Asia. ‘Oktoberfest’ is the variety usually grown.
Kamchatka Stonecrop, Sedum kamtschaticum – a plant from Siberia, with greenish leaves and yellow flowers. Hardy to zone 3, but often sheds its leaves in winter.
Mountain Stonecrop, Sedum repestre – another European species, this creeping plant has blue-green leaves on stems that spread wide. The leaves may turn reddish in fall, and the summer flowers are yellow. Only hardy to zone 5.
‘Oracle’ Stonecrop, Sedum fosterianum – this hardy variety is distinctive, with slender gray-green leaves radiating out from the stems.
Three-leaved Stonecrop, Sedum ternatum – this American plant is different from most, because it will tolerate shadier and damper places, often growing along streams in the wild. The green leaves wrap around the stem in whorls of three, and the tiny flowers are white.
Most of the taller varieties, those growing over 12 inches, have been moved by botanists into a new grouping called Hylotelephium. These plants have upright stems with larger leaves, and they are often grown among grasses and other perennial plants in gardens. They fit equally well into more formal or wilder gardens, and they are a great choice for xeric gardens as well.
The most common is the Autumn Joy Sedum, (Hylotelephium ‘Herbstfreude’), a showy plant with large, flattish heads of dusky-pink flowers in late summer, turning dark red in fall. Its long-lasting blooms top 2-foot stems, and it’s a good choice for filling in the front of beds. The stems die down to the ground over winter. The similar variety ‘Brilliant’ has vivid pink flowers, while ‘Thundercloud’ has white blooms.
When you need to bring some life to the hottest and driest parts of your garden, Sedums are the natural choice. For ground-cover in dry, sunny places they are the #1 choice – simply indispensable.