Propagation
The seed requires a period of cold stratification. The seed has a hard seedcoat and can be very slow to germinate, requiring a cold period followed by a warm period and then another cold spell, each of 2 - 3 months duration[78, 81]. Soaking the seed for 3 - 6 seconds in boiling water may speed up the germination process[11]. The seed is best sown as soon as it is ripe in a cold frame. Some might germinate in the following spring, though most will take another year. Another possibility is to harvest the seed 'green' (when the embryo has fully formed but before the seedcoat has hardened). The seedlings can be potted up into individual pots when they are large enough to handle. Grow on in pots until large enough, then plant out in early summer. When stored dry, the seed can remain viable for several years[1]. Cuttings of mature wood, 5 - 10cm with a heel, September/October in a cold frame. Plant out in the following autumn[1, 78]. Layering in September/October. Takes 12 months[78].
[11] Bean. W. Trees and Shrubs Hardy in Great Britain. Vol 1 - 4 and Supplement. Murray 1981
A classic with a wealth of information on the plants, but poor on pictures.
[78] Sheat. W. G. Propagation of Trees, Shrubs and Conifers. MacMillan and Co 1948
A bit dated but a good book on propagation techniques with specific details for a wide range of plants.
[81] Rushforth. K. Conifers. Christopher Helm 1987 ISBN 0-7470-2801-X
Deals with conifers that can be grown outdoors in Britain. Good notes on cultivation and a few bits about plant uses.
http://www.pfaf.org/database/plants.php?Ju...s+communis+nana