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Juglandaceae FAMILY Least Concern

Juglans regia

Juglans regia

Edibility
4/5
Medicinal
3/5

Safety & Hazards

None known

Cultivation Details

HabitDeciduous Tree
GrowthMedium

Juglans regia is reported to tolerate an annual precipitation of 31 to 147cm, an annual temperature in the range of 7.0 to 21.1°C and a pH in the range of 4.5 to 8.2[1]. The dormant plant is very cold tolerant, tolerating temperatures down to about -27°C without serious damage, but the young spring growth is rather tender and can be damaged by late frosts[1]. Some late-leafing cultivars have been developed, these often avoid damage from spring frosts and can produce a better quality timber tree. Requires a deep well-drained loam[2] and a sunny position sheltered from strong winds. Prefers a slightly alkaline heavy loam but succeeds in most soils[3, 4]. The walnut tree is frequently cultivated for its edible seed in temperate zones of the world, there are many named varieties[4, 5]. Newer cultivars begin producing nuts in 5 - 6 years; by 7 - 8 years, they produce about 2.5 tons of nuts per hectare[1]. Orchards on relatively poor, unirrigated mountain soil report 1.5 - 2.25 tonnes per hectare, orchards in well cultivated valleys, 6.5 - 7.5 tonnes per hectare[1]. According to the Wealth of India, a fully grown individual can yield about 185 kg, but 37 kg is more likely[1]. Trees grow well in most areas of Britain but they often fail to fully ripen their fruits or their wood in our cooler and damper climate[4, 6], they prefer a more continental climate. There are some very fine trees in Cornwall[7]. Walnuts can produce large healthy trees in many parts of Britain, but seedling trees often do not fruit reliably. Some European varieties have been developed that succeed in colder areas[6]. Seedling trees are said to take from 6 to 15 years to come into fruit from seed[6], but these cultivars usually start cropping within 5 years. Plants produce a deep taproot and they are intolerant of root disturbance. Seedlings should be planted out into their permanent positions as soon as possible and given some protection for their first winter or two since they are somewhat tender when young. Flower initiation depends upon suitable conditions in the previous summer. The flowers and young growths can be destroyed by even short periods down to -2°c[4], but fortunately plants are usually late coming into leaf. Some cultivars are self-fertile, though it is generally best to grow at least two different cultivars to assist in cross-pollination. Any pruning should only be carried out in late summer to early autumn or when the plant is fully dormant otherwise wounds will bleed profusely and this will severely weaken the tree. Plants produce chemicals which can inhibit the growth of other plants. These chemicals are dissolved out of the leaves when it rains and are washed down to the ground below, reducing the growth of plants under the tree[8, 9, 10]. The roots also produce substances that are toxic to many plant species, especially apples (Malus species), members of the Ericaceae, Potentilla spp and the white pines (certain Pinus spp.)[6]. Trees have a dense canopy which tends to reduce plant growth below them[9]. All in all, not the best of companion trees, it is also suggested that the trees do not like growing together in clumps[11]. Trees are said to inhibit the growth of potatoes and tomatoes[8]. Hybridizes with J. nigra[12]. This species is notably susceptible to honey fungus[6]. The bruised leaves have a pleasant sweet though resinous smell[13].

Propagation

The seed is best sown as soon as it is ripe in individual deep pots in a cold frame[14]. You need to protect it from mice, birds, squirrels etc. The seed usually germinates in late winter or the spring. Plant out the seedlings into their permanent positions in early summer and give some protection from the cold for their first winter or two. The seed can also be stored in cool moist conditions (such s the salad compartment of a fridge) over the winter and sown in early spring but it may then require a period of cold stratification before it will germinate[15, 14, 16]. Named varieties are propagated by budding. Cite as: Temperate Plants Database, Ken Fern. temperate.theferns.info. 2026-02-21. <temperate.theferns.info/plant/Juglans+regia>

Pollinators

Wind

References

  1. [1]Handbook of Energy Crops — Duke. J. · - · 1983 · https://hort.purdue.edu/newcrop/duke_energy/dukeindex.html · ISBN - ↩︎Published only on the Internet, excellent information on a wide range of both temperate and tropical plants.
  2. [2]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.
  3. [3]RHS Dictionary of Plants plus Supplement. 1956 — F. Chittendon. · Oxford University Press · 1951 · ISBN - ↩︎Comprehensive listing of species and how to grow them. Somewhat outdated, it has been replaced in 1992 by a new dictionary (see [ 200 ]).
  4. [4]Nuts. — Howes. F. N. · Faber · 1948 · ISBN - ↩︎Rather old but still a masterpiece. Has sections on tropical and temperate plants with edible nuts plus a section on nut plants in Britain. Very readable.
  5. [5]Cornucopia - A Source Book of Edible Plants. — Facciola. S. · Kampong Publications · 1990 · ISBN 0-9628087-0-9 ↩︎Excellent. Contains a very wide range of conventional and unconventional food plants (including tropical) and where they can be obtained (mainly N. American nurseries but also research institutes and a lot of other nurseries from around the world.
  6. [6]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.
  7. [7]Trees and Shrubs in Cornwall. — Thurston. ↩︎Trees and shrubs that succeed in Cornwall based on the authors own observations. Good but rather dated.
  8. [8]Companion Plants. — Philbrick H. and Gregg R. B. · Watkins · 1979 · ISBN - ↩︎Details of beneficial and antagonistic relationships between neighbouring plants.
  9. [9]Companion Planting for Successful Gardening. — Riotte. L. · Garden Way, Vermont, USA. · 1978 · ISBN 0-88266-064-0 ↩︎Fairly good.
  10. [10]Wild Food Plants of Indiana. — McPherson. A. and S. · Indiana University Press · 1977 · ISBN 0-253-28925-4 ↩︎A nice pocket guide to this region of America.
  11. [11]The Gardener's Assistant. — Thompson. B. · Blackie and Son. · 1878 · ISBN - ↩︎Excellent general but extensive guide to gardening practices in the 19th century. A very good section on fruits and vegetables with many little known species.
  12. [12]Trees of Central Texas. — Vines. R. A. · University of Texas Press · 1987 · ISBN 0-292-78958-3 ↩︎A good concise guide, it gives details of habitats and some of the uses of trees growing in Texas.
  13. [13]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.
  14. [14]Hardy Woody Plants from Seed. — McMillan-Browse. P. · Grower Books · 1985 · ISBN 0-901361-21-6 ↩︎Does not deal with many species but it is very comprehensive on those that it does cover. Not for casual reading.
  15. [15]Propagation of Trees, Shrubs and Conifers. — Sheat. W. G. · MacMillan and Co · 1948 · ISBN - ↩︎A bit dated but a good book on propagation techniques with specific details for a wide range of plants.
  16. [16]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.
  17. [17]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.
  18. [18]Wild Food in Australia. — Cribb. A. B. and J. W. · Fontana · 1976 · ISBN 0-00-634436-4 ↩︎A very good pocket guide.
  19. [19]Sturtevant's Edible Plants of the World. — Hedrick. U. P. · Dover Publications · 1972 · ISBN 0-486-20459-6 ↩︎Lots of entries, quite a lot of information in most entries and references.
  20. [20]Food for Free. — Mabey. R. · Collins · 1974 · ISBN 0-00-219060-5 ↩︎Edible wild plants found in Britain. Fairly comprehensive, very few pictures and rather optimistic on the desirability of some of the plants.
  21. [21]Britain's Wild Larder. — Loewenfeld. C. and Back. P. · David & Charles; Newton Abbot. · ISBN 0-7153-7971-2 ↩︎A handy pocket guide.
  22. [22]The Oxford Book of Food Plants. — Harrison. S. Wallis. M. Masefield. G. · Oxford University Press · 1975 · ISBN - ↩︎Good drawings of some of the more common food plants from around the world. Not much information though.
  23. [23]A Modern Herbal. — Grieve. · Penguin · 1984 · ISBN 0-14-046-440-9 ↩︎Not so modern (1930's?) but lots of information, mainly temperate plants.
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  28. [28]Edible and Medicinal Plants. — Launert. E. · Hamlyn · 1981 · ISBN 0-600-37216-2 ↩︎Covers plants in Europe. a drawing of each plant, quite a bit of interesting information.
  29. [29]Medicinal Plants of China — Duke. J. A. and Ayensu. E. S. · Reference Publications, Inc. · 1985 · ISBN 0-917256-20-4 ↩︎Details of over 1,200 medicinal plants of China and brief details of their uses. Often includes an analysis, or at least a list of constituents. Heavy going if you are not into the subject.
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  31. [31]Glossary of Indian Medicinal Plants (Including the Supplement). — Chopra. R. N., Nayar. S. L. and Chopra. I. C. · Council of Scientific and Industrial Research, New Delhi. · 1986 · ISBN - ↩︎Very terse details of medicinal uses of plants with a wide range of references and details of research into the plants chemistry. Not for the casual reader.
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  33. [33]Encyclopaedia of Herbs and their Uses. — Bown. D. · Dorling Kindersley, London. · 1995 · ISBN 0-7513-020-31 ↩︎A very well presented and informative book on herbs from around the globe. Plenty in it for both the casual reader and the serious student. Just one main quibble is the silly way of having two separate entries for each plant.
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  36. [36]Flowers of Europe - A Field Guide. — Polunin. O. · Oxford University Press · 1969 · ISBN 0192176218 ↩︎An excellent and well illustrated pocket guide for those with very large pockets. Also gives some details on plant uses.
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  39. [39]The Checklist of Species, Hybrids and Cultivars of the Genus Fuschia. — Boullemier. L. · Blandford Press · 1985 · ISBN 0-7137-1781-5 ↩︎Merely a list of names and the occasional elaboration.
  40. [40]Nature's Colors - Dyes from Plants. — Grae. I. · MacMillan Publishing Co. New York. · 1974 · ISBN 0-02-544950-8 ↩︎A very good and readable book on dyeing.
  41. [41]A Weavers Garden — Buchanan. R. · McGraw-Hill Contemporary · 1987 · ISBN 0934026289 ↩︎Covers all aspects of growing your own clothes, from fibre plants to dyes.
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  43. [43]Dictionary of Economic Plants. — Uphof. J. C. Th. · Weinheim · 1959 · ISBN - ↩︎An excellent and very comprehensive guide but it only gives very short descriptions of the uses without any details of how to utilize the plants. Not for the casual reader.
  44. [44]Plants with a Purpose. — Mabey. R. · Fontana · 1979 · ISBN 0-00-635555-2 ↩︎Details on some of the useful wild plants of Britain. Poor on pictures but otherwise very good.
  45. [45]Forest Flora of Srinagar. — Singh. Dr. G. and Kachroo. Prof. Dr. P. · Bishen Singh Mahendra Pal Singh · 1976 · ISBN - ↩︎A good flora of the western Himalayas but poorly illustrated. Some information on plant uses.
  46. [46]CosIng — http://ec.europa.eu/growth/tools-databases/cosing/ ↩︎CosIng is the European Commission database for information on cosmetic substances and ingredients.
  47. [47]A Dictionary of Plants Used by Man. — Usher. G. · Constable · 1974 · ISBN 0094579202 ↩︎Forget the sexist title, this is one of the best books on the subject. Lists a very extensive range of useful plants from around the world with very brief details of the uses. Not for the casual reader.
  48. [48]A - Z of Companion Planting. — Allardice.P. · Cassell Publishers Ltd. · 1993 · ISBN 0-304-34324-2 ↩︎A well produced and very readable book.
  49. [PFAF]Plants for a Future — pfaf.org ↩︎