How to Grow Lithodora
Glandora diffusa
Glandora (sold as Lithodora) is a low, spreading evergreen shrublet that produces a stunning flush of vivid blue flowers in late spring and early summer. Acid (ericaceous) soil is essential — it will not grow in alkaline or chalky conditions. Plant in full sun in well-drained ericaceous compost or naturally acidic soil. Water with rainwater where possible as tap water can be too alkaline. Trim lightly after flowering to keep plants compact, but never cut back into old bare wood.
Yearly Lifecycle
Care Essentials
Apply an ericaceous (acid) fertiliser in spring as new growth begins. Avoid any lime-based or general-purpose fertilisers which raise soil pH and cause yellowing.
Watch For
- Chlorosis (yellowing leaves) due to alkaline soil or hard tap water
- Root rot in waterlogged or poorly drained soil
- Vine weevil in containers
- Aphids on new shoots
Companions
Heather (Calluna), Rhododendron, Pieris, Dwarf conifers, Erica
Care Requirements
Light
Full sun essential
Needs at least 6 hours of direct sun daily for the best flowering and the most intense blue colour. Plants in shade produce fewer flowers and become straggly.
Watering
Moderate; avoid waterlogging; use rainwater
Water moderately during dry spells, especially when newly planted. Good drainage is critical — standing water quickly causes root rot. In hard-water areas, use rainwater as tap water is often too alkaline.
Fertilizing
Ericaceous (acid) feed in spring only
Apply an ericaceous fertiliser in spring as growth resumes. Avoid general-purpose or lime-containing feeds which raise soil pH and cause chlorosis. One application per year is usually sufficient.
Pruning
Light trim after flowering; never into old wood
Clip back flowered shoot tips by a few centimetres immediately after blooming to keep the mound compact. Never cut into old bare woody stems as the plant cannot regenerate from them.
Spacing
45-60 cm apart
Space plants 45-60 cm apart. They spread to 60 cm and will knit together to form a mat. Give them room from the start to avoid overcrowding.
Growing Tips
Acid soil is non-negotiable
Glandora will not grow in alkaline or chalky soil. Test pH before planting — it needs pH 5.0-6.0. If your soil is neutral or alkaline, grow in a container with ericaceous compost.
Trim after flowering, not before
Clip back the flowered shoot tips immediately after bloom to keep the plant dense and tidy. Never cut into old bare stems — Glandora will not regenerate from old wood.
Vivid blue needs full sun
The famous intense blue flower colour is strongest in full sun. Plants in partial shade produce fewer flowers and less vivid colour.
Use rainwater if possible
Tap water in hard-water areas is alkaline and will gradually raise the soil pH. Collect rainwater for watering, or use acidified water if chlorosis (yellowing) appears.
