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Clethraceae FAMILY Least Concern

Clethra alnifolia

Clethra alnifolia

Edibility
0/5
Medicinal
0/5

Safety & Hazards

None known

Cultivation Details

HabitDeciduous Shrub
Growth—

Clethra alnifolia is a very cold-tolerant plant, when dormant it is hardy to about -30°c[1, 2]. Prefers a moist but well-drained lime-free sandy and peaty soil[3, 4], though it is adaptive to a wide range of soil, moisture and light conditions[5].. It loves abundant moisture at its roots[3]. Prefers a sunny position or partial shade[6]. The plant is moderately salt tolerant, and can be grown near, but not directly behind, beaches[7]. A good bee plant[8], the flowers are very aromatic[PFAF]. There are some named varieties developed for their ornamental value. 'Paniculata' has longer-lasting branching panicles of flowers[4]. Like the species type, the flowers of this cultivar are very sweetly scented[9]. Suckers are freely produced when the plant is grown in conditions similar to its natural habitat[2], the plant forming thickets[4]. Plants in this genus are notably resistant to honey fungus[2].

Propagation

Seed - sow early spring in a greenhouse[10]. Only just cover the seed and keep the pot moist. Germination usually takes place within 1 - 3 months at 13°c[6]. When large enough to handle, prick the seedlings out into individual pots and grow them on in the greenhouse for at least their first winter. Plant them out once they are more than 20cm tall in late spring or early summer after the last expected frosts. Cuttings of half-ripe wood, 7 - 10cm with a heel, mid summer in a frame[3, 10]. Very easy[10]. Root cuttings in December/January[10]. Suckers in the dormant season[10]. They can be planted out direct into their permanent positions if required. Layering of current years growth in late autumn. Takes 18 months. Can also be done in early spring[2]. Cite as: Temperate Plants Database, Ken Fern. temperate.theferns.info. 2026-02-20. <temperate.theferns.info/plant/Clethra+alnifolia>

Pollinators

Bees, Butterflies, Hummingbirds

References

  1. [1]Shrubs. — Phillips. R. & Rix. M. · Pan Books · 1989 · ISBN 0-330-30258-2 ↩︎Excellent photographs and a terse description of 1,900 species and cultivars.
  2. [2]The New RHS Dictionary of Gardening. 1992. — Huxley. A. · MacMillan Press · 1992 · ISBN 0-333-47494-5 ↩︎Excellent and very comprehensive, though it contains a number of silly mistakes. Readable yet also very detailed.
  3. [3]Trees and Shrubs Hardy in Great Britain. Vol 1 - 4 and Supplement. — Bean. W. · Murray · 1981 · ISBN - ↩︎A classic with a wealth of information on the plants, but poor on pictures.
  4. [4]Ornamental Shrubs, Climbers and Bamboos. — Thomas. G. S. · Murray · 1992 · ISBN 0-7195-5043-2 ↩︎Contains a wide range of plants with a brief description, mainly of their ornamental value but also usually of cultivation details and varieties.
  5. [5]KemperCentreForHomeGardeningPlantFinder — Missouri Botanical Garden · http://www.mobot.org/gardeninghelp/plantfinder/ ↩︎Basic cultivation details, plant uses, habitat etc for several thousand species of plants, mainly from the temperate zone.
  6. [6]Growing from Seed. Volume 4. — Bird. R. (Editor) · Thompson and Morgan. · 1990 · ISBN - ↩︎Very readable magazine with lots of information on propagation. A good article on Yuccas, one on Sagebrush (Artemesia spp) and another on Chaerophyllum bulbosum.
  7. [7]Plants Database — United States Department of Agriculture · http://plants.usda.gov/java/factSheet ↩︎An online database with an excellent collection of fact sheets about native N. American plants.
  8. [8]The Dictionary of Useful Plants. — Coon. N. · Rodale Press · 1975 · ISBN 0-87857-090-x ↩︎Interesting reading but short on detail.
  9. [9]Scented Flora of the World. — Genders. R. · Robert Hale. London. · 1994 · ISBN 0-7090-5440-8 ↩︎An excellent, comprehensive book on scented plants giving a few other plant uses and brief cultivation details. There are no illustrations.
  10. [10]The Reference Manual of Woody Plant Propagation. — Dirr. M. A. and Heuser. M. W. · Athens Ga. Varsity Press · 1987 · ISBN 0942375009 ↩︎A very detailed book on propagating trees. Not for the casual reader.
  11. [11]Flora of N. America — http://flora.huh.harvard.edu/fna/ ↩︎An on-line version of the flora with an excellent description of the plant including a brief mention of plant uses.
  12. [12]IUCN Red List of Threatened Species — http://www.iucnredlist.org/ ↩︎A list of plants under threat and facing possible extinction, usually with brief details of the threats and information on habitat.
  13. [13]Gray's Manual of Botany.Eighth Edition — Fernald. M. L. · American Book Co.; New York · 1950 · ISBN 0442222505 ↩︎A bit dated but a good and concise flora of the eastern part of N. America.
  14. [PFAF]Plants for a Future — pfaf.org ↩︎