How to Plant and Grow Silene

Silene is a genus of approximately 900 flowering annuals and perennials, some native to the North American grasslands. Annual silene (often found in prairies and meadows) boasts early summer flowers in pretty shades of pink, white, red, and magenta. It lasts just one year but readily self-seeds to germinate new plants each spring.   Perennial silene, on the other hand, can return to the same spot year after year.

Silene also goes by the common name catchfly, a name it earned thanks to the plant's sticky leaves and stems. Anecdotally, it is said that the leaves and stems are so sticky they could catch a fly; but the sticky stems actually discourage ants and other small insects from snacking on the plant.

Where to Plant Silene

Silene is often used in rock gardens, curbside plantings, and full-sun garden borders. In these dry, sometimes inhospitable conditions, other plants may perish, but silene flourishes. When in bloom, silene draws in welcome visitors (like butterflies, bees, and nocturnal moths), so it also makes a great addition to pollinator gardens, cottage gardens, and wildflower gardens.  

In favorable conditions, silene can become weedy. If unmanaged, some species may crowd out other plants. Contain your silene by planting it in a garden box or hanging planter where the foliage and flowers can spill over the sides. Or, to avoid displacing local wildlife, look for native options like wild pink silene (S. caroliniana), royal catchfly (S. regia), fire pink silene (S. virginica), or starry campion (S. stellata).

How and When to Plant Silene

You can sow silene seeds directly in the ground in the fall or in the spring about 3 weeks before the last frost. To plant your seeds, moisten and loosen the top several inches of soil. Press your seeds gently into the soil but do not cover them as the seeds need sunlight for germination. Place your seeds about 6 to 18 inches apart (depending on species and projected mature size). If your soil is moist enough when you start, you should not need to water the seeds once planted. As the seeds germinate, keep the soil evenly moist but not wet. Seedlings should emerge in 2 to 3 weeks.

You can also plant nursery-grown silene plants in the spring after the danger of frost has passed. Dig a hole in loosened soil that is slightly wider, but no deeper than the plant’s root ball. Place your silene plant in the hole and secure it by gently tamping down the soil. Water well and keep the soil evenly moist until the plant is established.

Silene Care Tips

Silene is an eye-catching annual or perennial that is relatively easy to maintain. Plan to replace perennial silene in your landscape every few years. Perennial cultivars tend to decrease flower production as they age.

Light

Most silene species prefer full sun to partial shade. However, there are a few species, like starry campion (S. stellata) that prefer partial shade. These silene plants become pale or yellow when grown in full sunlight. In warmer climates (zones 7 and above), nearly all silene species fare better with afternoon shade.

Soil and Water

Ideal soil conditions are dependent upon species, but most silene plants do best in moist, well-drained soils with a neutral or alkaline pH. There are a few silene species (particularly those native to the rocky slopes and bluffs of central and eastern United States) that prefer dry to medium-moist well-drained sandy or lightly loamy soils. Either way, well-drained soil is essential. Silene suffers and dies out in wet locations.

New silene plants may need supplemental water while getting established, but just enough to keep the soil evenly moist. Otherwise, silene is drought tolerant. So, let the soil dry out between waterings.

Temperature and Humidity

Silene does not fare well in hot, humid climates. While temperature requirements vary among species, most prefer moderate temperatures between 50˚ and 75˚ Fahrenheit. When the temperature drops, flowering may slow or stop. Over the winter, annual plants will die and perennial silene plants will go dormant.

Fertilizer

Silene does not require fertilizer, but if you feel your soil is not nutrient-rich enough, incorporate a little compost into the hole when planting, dividing, or transplanting. Alternatively, you can add a bit of granulated fertilizer at the beginning of the blooming season.

Pruning

The pruning process for silene depends on the species. With most silene, you can deadhead spent blossoms throughout the summer to encourage more flowers and prevent self-seeding. Once flowering is finished, you can cut back or mow over the plants if you prefer a tidier look. This is not, however, a necessary step. Even without pruning, perennial plants will return and annual plants will self-seed and germinate new plants in the spring.

Potting and Repotting

Silene works beautifully in containers and it requires little extra care than for those grown in the ground. Choose a large container (at least 12 inches wide and deep) with excellent drainage and fill it with a moist, well-draining neutral to alkaline potting mix. Approximately 3 weeks before the last frost, sow several seeds on the surface of the soil, pressing them in just slightly. Keep your container in a sunny location with shelter from the harshest afternoon rays. Keep the soil evenly moist (but not wet) as the seeds germinate. Once the seedlings emerge, thin them to about 6 inches apart, keeping only the most viable.

Repot or divide your silene plant (in the late fall or early spring) every 2 to 3 years or when you see roots emerge from the drainage holes. Use fresh potting mix in each container as you divide or move.

Pests and Problems

Despite its common name (catchfly) silene has no serious disease or insect issues—although aphids and slugs may be problematic in some regions.

Types of Silene

Rose Campion

Rose campion (Silene coronaria) is a short-lived perennial (and sometimes biennial) that is often included in the genus Lychnis. It is native to southeastern Europe but has been naturalized in the United States. It bears woolly, silvery-green foliage and small, bright magenta, pink, or white-hued flowers in zones 4-10. Rose campion readily self-seeds and has the potential to become invasive if not managed or contained.

Starry Campion

Starry campion (Silene stellata) is a wildflower native to the thickets, meadows, and prairies of the eastern and central United States. It grows about 1 to 3 feet tall and bears fringed, star-like flowers for several weeks in the summer. It is grown as a perennial in zones 5-8 and self-seeds at a gentle pace.

Royal Catchfly

Royal catchfly (Silene regia) has 2-inch-wide fiery scarlet flowers in summer on stems that may reach 4 feet tall. The foliage is downy and covered with fine hairs. It is beloved by pollinators and an excellent choice for prairie gardens, pollinator gardens, and native plant gardens in Zones 4–7.

'Clifford Moor' Catchfly

'Clifford Moor' catchfly (Silene dioica) offers pink flowers in early summer over variegated leaves with dark green centers and wide gold margins. This cultivar prefers sunny locations and sandy, somewhat dry soils with excellent drainage in zones 5–8. It is an excellent choice for rock gardens, especially in areas where it gets a little afternoon shade.

Companion Plants for Silene

Black-Eyed Susan

Black-eyed Susan makes a sunny companion for silene in zones 3-10. The native Midwest flowering plants also prefer moist to dry well-draining soil and are perfectly at home in butterfly gardens, beds, borders, mass plantings, and containers.

Coneflower

Coneflower (Echinacea purpurea) is a cottage and wildflower garden favorite with big daisy-like flowers that bloom from summer to fall. Coneflowers are unfussy about soil (but don't like things too wet) and they adapt to a wide range of climates in zones 3-9. They can also tolerate more sun exposure than most silene plants, so place them at the sunnier edges of your garden plot.

Sea Holly

Sea holly thrives in challenging spots—like hot, sunny, dry, sites and sandy soils. It's also a favorite among butterflies, birds, and bees. The stunning steely-blue thistlelike flower heads last a long time and add texture to any garden (zones 4-8) with dry, poor soil. As with silene, sea holly's greatest weakness is too much water. Avoid overwatering (or watering at all) and your sea holly should fare just fine.