Thesium pyrenaicum
Thesium pyrenaicum · Thesiaceae
The gardener's calendar
Ideal time to plant thesium pyrenaicum: set it out when the soil is neither frozen nor waterlogged, and water generously as it establishes.
ID card
- Common name
- Pyrenean Thesium
- Family
- Thesiaceae
- Type
- Perennial herbaceous plant
- Blooming
- May to July
- Adult size
- 20 to 50 cm in height
- Foliage
- Deciduous
- Hardiness
- Very hardy (zone 4-8)
- Origin
- Pyrenees mountain range (Europe)
- Soil
- Well-drained, dry to moderately moist
Care
Light exposure
Plant in full sun or partial shade for optimal growth. Thesium pyrenaicum prefers bright, well-aerated spaces, typical of its mountain habitat. A minimum of 6 hours of sunlight per day promotes flowering.
Watering
Water moderately during the growing season, keeping the soil slightly moist without excess. Once established, this perennial is tolerant of relative dryness and withstands drier periods well. Avoid standing water, which is detrimental to its roots.
Soil and drainage
Plant it in well-drained soil, ideally poor to moderately fertile and preferably chalky or neutral. Heavy, compacted soils should be lightened with sand or gravel. Good drainage is essential for the plant's long-term survival.
Pruning and maintenance
Prune lightly after flowering to encourage branching and maintain a compact shape. In late winter, remove dead wood. No severe pruning is necessary: light cutting is sufficient to rejuvenate the plant.
Fertilization
Apply a balanced fertilizer in spring, just once, or enrich the soil during planting with moderate compost. Thesium pyrenaicum does not need repeated fertilizing; poor soil actually suits this alpine plant better.
Health and protection
Very robust, this perennial remains relatively insensitive to major diseases and pests. Monitor excess winter moisture, which could promote root rot. Good drainage prevents most health problems.
Did you know?
Thesium pyrenaicum is a semi-parasitic plant: its roots are equipped with suction structures that allow it to extract water and nutrients from the roots of neighboring herbaceous plants. Despite this original survival strategy, it often enriches the mountain ecosystems of the Pyrenees where it grows naturally and remains harmless in cultivated gardens.
Where to buy it
Plant in spring or early autumn, avoiding spells of intense heat. Pick a plant with healthy foliage and roots that are not exposed. Best time: March, April, May, September.
Add this plant to my garden →Plants from the same family
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Tips generated and checked by Viridia — adapt them to your local climate.