Editing Chestnut (section)

==== Climate and seasonal germination cycle ====
Chestnuts produce a better crop when subjected to chill temperatures during the [[dormancy|dormant]] period. [[Frost#Effect on plants|Frosts]] and snowfalls are beneficial rather than harmful to the trees.<ref name="chestnutbrook" /><ref name="laren60" /> The dormant plant is very cold-hardy in Britain,<ref name="KenFern">Ken Fern. Notes from observations, tasting, etc. at ''Plants for a Future'' and on field trips. Cited in ''Plants for a Future''</ref> to the [[Royal Horticultural Society]]'s H6 hardiness rating, to -20&nbsp;°C.<ref>{{cite web |title=Castanea sativa, sweet chestnut |url=https://www.rhs.org.uk/Plants/3191/Castanea-sativa/Details |access-date=13 August 2020 |website=Find a Plant |publisher=Royal Horticultural Society}}</ref> Chestnut is [[Hardiness zone|hardy to USDA zone 5]], which is {{cvt|-20|F|order=flip}} lower in average minimal temperature than [[London#Climate|London]] in [[Hardiness zone|zone 9]].<ref name="pfaf">[http://www.pfaf.org/database/plants.php?Castanea+sativa Castanea sativa – Mill.] in ''Plants for a Future''.</ref> The young growth in spring, even on mature plants, however, is [[frost]]-tender;<ref name="KenFern" /><ref name="pfaf" /> [[bud]]-burst is later than most other fruit trees, so late frosts can be damaging to young buds.<ref name="laren60" />

Trees can be found at altitudes between 200 and {{nowrap|1000 m}} above sea level;<ref name="laren60" /> some mention between 300 and {{nowrap|759 m}} altitude,<ref name="lille">[http://www.univ-lille1.fr/pfeda/iaal/docs/iaal2002/crem/rapport/crememarron.pdf ''Étude d'un produit régional: La crème de marrons'']. By Sabrina Derouet, Flavie Dhellemmes, Lamia Hakam, Claire Lhaoucine and Maxime Vanhoutte. EPU Lille-USTL. 2003.</ref> while the famous [[Hundred Horse Chestnut]] on [[Mount Etna]] stands at 1200 metres.<ref name="rushton">[http://digicoll.library.wisc.edu/cgi-bin/HistSciTech/HistSciTech-idx?type=turn&entity=HistSciTech001201260012&isize=text The Chestnut tree of Mount Etna]. Detailed account of the tree, its state and its surroundings, written by Wm. Rushton on June 29, 1871.</ref> They can tolerate maritime exposure, although growth is reduced.<ref name="pfaf" />

Seeds [[germination|germinate]] in late winter or early spring,<ref name="KenFern" /><ref name="pfaf" /> but the life length is short. If kept moist, they can be stored in a cool place for a few months, but must be checked regularly for signs of germination.<ref name="pfaf" /> Low temperature prolongs dormancy.<ref name="fao" /> Sowing them as soon as ripe is better, either in [[cold frame]]s or [[seedbed]]s outdoors,<ref name="sheat">''Propagation of Trees, Shrubs and Conifers.'' By W. G. Sheat. MacMillan and Co 1948. Cited in ''Plants for a Future''.</ref> where they can be left ''in situ'' for one to two years before being planted in their permanent positions,<ref name="pfaf" /> or in pots, where the plants can be put out into their permanent positions in summer or autumn. They must be protected from the cold in their first winter,<ref name="KenFern" /> and also from [[mouse|mice]] and [[squirrel]]s.<ref name="pfaf" />

Chestnuts are considered self-sterile,<ref name="pfaf" /><ref name="song">[http://www.songonline.ca/nuts/chestnut.htm Sweet Chestnut (''Castanea'' species)]. Society of Ontario Nut Growers.</ref> so at least two trees are needed for pollination.<ref name="delmarvelous" />