Snow-in-summer (Cerastium tomentosum 'Yo Yo')
Cerastium tomentosum 'Yo Yo' (Snow-in-summer) is a drought-tolerant perennial ground cover known for its stunning white summer blooms and silver foliage.
Scroll down to discover growing tips, care requirements, companion plants, and more
Complete Plant Information
Overview
Cerastium tomentosum ‘Yo Yo’, commonly known as Snow-in-summer, is a striking herbaceous perennial valued for its dense, silver-gray foliage carpet. This plant creates a stunning visual effect when masses of small white flowers cover the mat in early summer, truly resembling fresh snow across the landscape. As a ground cover, it spreads via runners, quickly stabilizing dry, sunny banks or rocky areas.
This cultivar offers a more manageable footprint than the standard species, making it an excellent choice for gardeners wanting intense coverage without aggressive spreading. While beautiful, be aware that Snow-in-summer requires diligent care in hot, humid summers, as the foliage tends to decline quickly under stress.
Its unique combination of silvery leaves and brilliant white blooms provides texture and contrast throughout the growing season in difficult, dry exposures. For best results, ensure plants receive ample sunlight and excellent drainage, allowing this tough perennial to thrive.
Fast Facts
- Plant Family: Caryophyllaceae
- Plant Type: Herbaceous perennial
- Hardiness Zones: USDA Zones 3-7
- Size at Maturity:
- Height: 0.5-1 ft
- Spread: 0.5-1.5 ft
- Bloom Time: June to July
- Bloom Description: White
- Sun Exposure: Full sun
- Water Needs: Dry
- Maintenance Level: Medium
How to Grow
Cerastium tomentosum ‘Yo Yo’ thrives best when planted in dry, sandy, well-drained soils, provided it receives full, unobstructed sun exposure throughout the day. It tolerates many soil types, but poorly-drained soils are fatal, inevitably causing root rot, especially in less hardy Zone 2 climates. Plan to space starter plants about 9 to 12 inches apart to allow them room to spread and form a continuous mat quickly.
Watering requirements are minimal once established, as this plant is highly drought-tolerant—a key feature beneficial for rockeries or dry borders. Feeding is generally unnecessary, as rich or wet conditions encourage lush, floppy growth that compromises the plant’s structure and health. While it handles cooler summers beautifully, plants tend to struggle and decline rapidly when exposed to hot, humid summer conditions.
Maintenance for Snow-in-summer involves shearing. After the primary bloom cycle in June and July finishes, shear the stems back. This action achieves three vital goals: it prevents unwanted self-seeding, promotes cleaner foliage decline prevention, and neatly shapes the mat. For very large areas, mowing the bed on a high setting after flowering is an effective alternative. If the mat becomes too thick or patchy after several years, division is recommended annually to maintain a compact size.
Landscape Uses
The compact, creeping nature of Cerastium tomentosum ‘Yo Yo’ makes it an ideal, silvery ground cover for sunny locations where drought tolerance is essential. It excels at softening the hard edges of pathways or covering bare soil between stepping stones, often utilized in rock gardens or dry stone wall planting pockets. Its low profile makes it perfect for use as a border front edging plant, keeping sightlines clear near taller specimens.
Consider using Snow-in-summer to blanket the ground beneath spring-blooming bulbs; the foliage covers the dying bulb leaves as they fade, keeping the garden looking tidy. In cottage garden settings, its silvery foliage pairs wonderfully against the deep greens and bright colors of traditional perennials. Because of its tough nature, it is widely recommended for naturalizing on slopes or banks where maintaining turf grass is difficult.
Standout Features
Flower Qualities
- Showy
Noteworthy Characteristics
Cerastium tomentosum, known as snow-in-summer, is a short-lived, low-growing, mat-forming perennial which is typically massed in sunny locations as a ground cover. Tufts of narrow, gray-green leaves (each to 1” long and 1/4” wide) form a 6” tall foliage mat with evergreen leaves. In late spring, flower stems rise above the foliage mat carrying clusters of white blooms which form a snow-like carpet. The ‘Yo Yo’ cultivar is specifically valued for being more compact, slower spreading, and less aggressive than the straight species.
Tolerances
- Deer
- Drought
- Dry Soil
- Shallow-Rocky Soil
Potential Problems
The primary challenge with Snow-in-summer relates to moisture management. Root rot poses a serious threat if the plant is sited in poorly-drained or consistently wet soils; absolute drainage is critical for the health of Cerastium tomentosum ‘Yo Yo’. In environments characterized by high humidity or excessive shade, issues like damping off can occur, especially in young plants. Furthermore, this perennial is inherently short-lived; expect to see dead patches appear within the mat after several years, necessitating division or replacement. Gardeners in hot, humid climates should anticipate foliage decline as the summer heat progresses.
Frequently Asked Questions
What hardiness zones is Snow-in-summer suitable for?
Cerastium tomentosum ‘Yo Yo’ is suitable for USDA Zones 3 through 7, offering excellent cold hardiness.
How large does Snow-in-summer grow?
This mat-forming perennial typically reaches a height between 0.5 and 1 foot tall, spreading out to cover an area 0.5 to 1.5 feet wide.
When does Snow-in-summer bloom?
Snow-in-summer produces its signature white blooms primarily from June through July, providing a spectacular summer display.
What sun exposure does Cerastium tomentosum ‘Yo Yo’ need?
This plant requires full sun exposure to maintain its dense habit and produce abundant flowers.
Conclusion
Cerastium tomentosum ‘Yo Yo’ delivers exceptional value as a tough, drought-tolerant ground cover, instantly brightening dry, sunny spots with its silver foliage and cloud-like white flowers. If you are seeking reliable coverage for rock gardens or borders where water conservation is key, Snow-in-summer is a superb choice. Always confirm your local conditions align with USDA Zones 3-7 and prioritize excellent soil drainage before planting.
Companion Planting Considerations
When selecting companions for Snow-in-summer, focus on plants that also prefer full sun and dry, well-drained soil conditions. Pairing it with other drought-tolerant, low-growing herbs or Mediterranean plants works well visually and culturally. Consider low-growing Sedums, Lavender varieties, Thyme, or creeping Phlox, which share similar cultural needs and won’t compete aggressively in your planting bed. The silvery texture of the foliage on Cerastium tomentosum ‘Yo Yo’ contrasts beautifully against the deeper greens and blues of these sun-loving partners.
Seasonal Care Calendar
Early Spring is the ideal time to clean up any winter debris and assess the mat for dead patches requiring replacement or division of nearby healthy clumps. In late Spring (just before flowering), this is the best time to plan any necessary edging or shaping to prepare for the summer show. Immediately Post-Bloom (mid-summer), shear the foliage back by one-third to one-half to neaten the appearance and discourage unwanted reseeding. In late Fall, if you choose not to shear hard after bloom, the evergreen foliage will provide some winter interest, though heavy snow or ice in wet areas can sometimes cause damage.
