Alkali marsh aster
Symphyotrichum pilosum · Asteraceae
📷 Elizabeth Ballard · CC BY-SA 4.0
The gardener's calendar
In autumn, ease off feeding and take the chance to clean up around alkali marsh aster and prepare for winter.
ID card
- Foliage
- Deciduous
- Flowering
- Fall (September to November)
- Adult size
- 24 to 40 inches tall
- Growth
- Fast
- Hardiness
- Very hardy (down to -4°F)
- Origin
- North America
- Soil type
- Well-drained, moderately fertile soil
Expert tips
The key tip
L'aster poilu prospère en sol bien drainé et craint l'humidité stagnante bien plus que la sécheresse : une fois établi, arrosez modérément et laissez-le sécher entre deux apports. Taillez légèrement en fin d'hiver pour compacter la souche et favoriser une floraison dense plutôt que quelques fleurs éparses sur des tiges élancées.
The common mistake
La plupart des jardiniers arrosent trop, surtout en automne : l'aster poilu meurt d'excès d'eau bien plus souvent qu'il ne souffre de la sécheresse, particulièrement en sol lourd ou mal drainé.
The pro's trick
En mai-juin, pincez les extrémités des jeunes tiges (enlever 2-3 cm) : vous transformerez une plante maigre en buisson compact qui produit trois fois plus de fleurs en septembre-octobre.
Seasonal watch
En automne humide et frais, surveille l'oïdium (poudre blanche sur les feuilles) : dès les premiers signes, supprime les parties atteintes et aère mieux entre les touffes pour faire circuler l'air, sinon la fleur devient invisible sous le feuillage malade.
Care
Watering
Water regularly during the growing season, especially during prolonged dry spells. Once established, hairy aster tolerates drought well and requires only moderate watering. Avoid excess moisture, which promotes fungal diseases.
Light Exposure
Plant hairy aster in full sun (at least 6 hours per day) for generous flowering. It also accepts partial shade, but flower production will be reduced and the plant may become slightly etiolated.
Pruning and Cutting
Prune stems in late winter or early spring before growth resumes. To encourage denser branching and more flowers, you can pinch back the tips before flowering. Cut back faded stems after blooming for aesthetic purposes.
Fertilizing
A balanced fertilizer application in spring is usually sufficient. Avoid excess nitrogen, which promotes foliage at the expense of flowering. Light compost applied at the base early in the season naturally enriches the soil.
Soil
Hairy aster prefers well-drained and slightly dry soil. Incorporate sand or coarse materials if your soil is too compact or clay-based. Soil that is too rich in organic matter can reduce hardiness and promote diseases.
Diseases and Pests
This plant is generally robust. Watch for powdery mildew in warm, humid weather: good spacing between plants and adequate air circulation prevent the problem. Pests are rare; monitoring for spider mites during prolonged drought is usually sufficient.
Did you know?
Hairy aster gets its nickname from the fine glandular down that covers its stems and leaves, particularly visible in raking light. Once widely hybridized, this North American aster served as a parent to many garden varieties, including some of the finest for fall bouquets.
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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- Canadian goldenrodSolidago canadensis
- WormwoodArtemisia absinthium
Tips generated and checked by Viridia — adapt them to your local climate.