Soil & potting mix
Best soil for Silverbush (Convolvulus cneorum)
Also called Silverbush, Bush morning glory, Shrubby bindweed.
More about silverbush
About Silverbush
Convolvulus cneorum · also called Silverbush, Bush morning glory · flowering
Convolvulus cneorum is a compact, evergreen Mediterranean shrub native to rocky limestone hillsides of the western Mediterranean basin, prized for its intensely silvery, silky foliage and a long succession of white funnel-shaped flowers flushed pink in bud. It must have full sun and sharp drainage — poor drainage, especially combined with winter wet, is the most common cause of death. Keep it in low-fertility soil to maintain compactness and vigour. It is not considered toxic to pets or humans.
Preferred mix: Well-drained chalk, loam, or sand; low to moderate fertility
Watch for — Root rot / winter wet: The leading cause of plant loss; ensure beds drain freely and consider raising plants on mounds or in containers in high-rainfall gardens.
Why silverbush needs this mix
Silverbush flowers hardest in a rich but free-draining loam — fed enough to fuel the display, open enough that the roots never waterlog.
- Flowering is expensive for silverbush: producing buds, blooms and seed draws heavily on nutrients and steady moisture, so the soil has to keep delivering all season.
- A loam-based mix holds nutrients and water far more evenly than a light peat mix, which means a longer, more reliable flowering period.
- It still needs sharp drainage — most flowering plants resent cold, wet feet far more than they resent being a little lean.
For the full picture on what makes up a good mix, see our guide to the main types of soil and potting media — it explains why each ingredient above behaves the way it does.
What goes wrong with the wrong mix
The wrong soil is one of the most common reasons silverbush struggles, and the damage often shows up weeks later as a watering problem. For this species specifically:
- A thin, hungry or sandy mix gives silverbush weak growth and few, short-lived flowers — it simply runs out of fuel.
- A heavy, badly drained soil rots the roots or crown, often over a wet winter, and you lose the plant before it ever flowers again.
- Over-rich, high-nitrogen mixes can push lush leaf at the expense of flowers — balance, not excess, is the aim.
Either starving silverbush in a thin mix or drowning it in a heavy, badly drained one. It wants the rich-but-free-draining middle, plus a flowering (higher-potassium) feed in season.
pH — does it matter for silverbush?
Most flowering plants, including silverbush, do well around pH 6.0-7.0. A cheap soil test is worth it outdoors; one notable exception is any acid-lover (such as some hydrangeas), where pH directly changes flower colour.
If you want to check or adjust it, the soil pH guide walks through testing and the safe ways to nudge a mix more acidic or more alkaline.
DIY mix vs a bagged one
A quality bagged compost works for silverbush in pots if you add grit and a flowering feed. In beds, improving the existing soil with compost and ensuring drainage beats any bag.
Drainage and the pot
Free drainage protects the roots and especially the crown over winter — raised beds, grit in the planting hole and never a waterlogged spot. Containers must have a clear drainage hole.
For perennials, refresh the top layer and feed each spring rather than disturbing the roots; for container displays, start with fresh rich mix each season. When the time comes, our repotting guide for silverbush covers the timing and technique step by step.
Silverbush soil — frequently asked questions
What is the best soil mix for silverbush?
3 parts good loam or quality peat-free compost : 1 part well-rotted compost or leaf mould : 1 part grit or perlite. Flowering is expensive for silverbush: producing buds, blooms and seed draws heavily on nutrients and steady moisture, so the soil has to keep delivering all season.
Can I use normal potting soil for silverbush?
A thin, hungry or sandy mix gives silverbush weak growth and few, short-lived flowers — it simply runs out of fuel. A quality bagged compost works for silverbush in pots if you add grit and a flowering feed. In beds, improving the existing soil with compost and ensuring drainage beats any bag.
Does silverbush need a special pH?
Most flowering plants, including silverbush, do well around pH 6.0-7.0. A cheap soil test is worth it outdoors; one notable exception is any acid-lover (such as some hydrangeas), where pH directly changes flower colour.
Should I buy a bagged mix or make my own for silverbush?
A quality bagged compost works for silverbush in pots if you add grit and a flowering feed. In beds, improving the existing soil with compost and ensuring drainage beats any bag.
How often should I refresh the soil for silverbush?
For perennials, refresh the top layer and feed each spring rather than disturbing the roots; for container displays, start with fresh rich mix each season. Free drainage protects the roots and especially the crown over winter — raised beds, grit in the planting hole and never a waterlogged spot. Containers must have a clear drainage hole.
Keep reading
- Silverbush care — the full brief (light, water, humidity, problems, pet safety)
- How often to water silverbush — the schedule the mix feeds into
- Repotting silverbush — when and how to refresh the mix
- Soil pH guide — test it and adjust it safely
- Should I water my plant? The simple check first
- Why is my plant wilting? Wet vs dry diagnosis
- Root rot — how the wrong soil starts it, and how to save the plant
- Best soil for front range beardtongue
- Best soil for sidebells penstemon
- Best soil for texas bluebonnet
- All 10153 soil and potting-mix guides in the Growli library