Troubleshooting
Columnae Snow-in-Summer problems — and how to fix them
Columnae Snow-in-Summer (Cerastium tomentosum 'Columnae') is generally forgiving once you match its basics, but a few issues come up again and again. Here is what each one looks like, why it happens, and the fix.
Crown rot in wet or heavy soils
The most serious risk; Cerastium tomentosum 'Columnae' is highly intolerant of wet roots, especially in winter. Ensure very sharp drainage before planting. Raise beds or plant on slopes and in rock crevices. Remove any decaying material promptly and do not mulch over the crown.
Post-flowering tatty appearance
After the main flush of flowers in late spring, the plant can look untidy with faded blooms and sprawling stems. Shear lightly with scissors or shears immediately after flowering to encourage a fresh flush of silvery foliage and maintain a tidy, compact mat. This also reduces self-seeding.
Self-seeding and minor invasiveness
Although 'Columnae' is less aggressive than the straight species, it will self-seed in suitable dry, open soils. Deadhead promptly after flowering to prevent unwanted seedlings. Rogue seedlings may not come true to type and may revert to the more spreading species form.
Prevent columnae snow-in-summer problems before they start
Most columnae snow-in-summer issues are care-mismatch, not bad luck. Dial in the basics:
Columnae Snow-in-Summer problems — FAQ
Why is my columnae snow-in-summer crown rot in wet or heavy soils?
The most serious risk; Cerastium tomentosum 'Columnae' is highly intolerant of wet roots, especially in winter. Ensure very sharp drainage before planting. Raise beds or plant on slopes and in rock crevices. Remove any decaying material promptly and do not mulch over the crown.
Why is my columnae snow-in-summer post-flowering tatty appearance?
After the main flush of flowers in late spring, the plant can look untidy with faded blooms and sprawling stems. Shear lightly with scissors or shears immediately after flowering to encourage a fresh flush of silvery foliage and maintain a tidy, compact mat. This also reduces self-seeding.
Why is my columnae snow-in-summer self-seeding and minor invasiveness?
Although 'Columnae' is less aggressive than the straight species, it will self-seed in suitable dry, open soils. Deadhead promptly after flowering to prevent unwanted seedlings. Rogue seedlings may not come true to type and may revert to the more spreading species form.