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Sowing of Trees and Shrubs: The Importance of Fresh Seeds

3 months ago

I have been sowing seeds of woody plant species for more than 20 years. In that time I have gained a lot of experience with the germination of many different species. One point that in my view has not been emphasized enough is the 'freshness' of the seeds. Some seeds can be stored cold and dry for many years without losing viability (most Viburnum species and many members of the Fabaceae for example). There are however some woody species whose seeds do not tolerate dry storage for very long. These seeds are 'recalcitrant' and should be sown shortly after harvesting. Some can be stored directly after harvest cold AND moist in slightly moist vermiculite or sowing compost (ziplock bags in the refrigerator) for a limited period. I have stored Magnolia cylindrica seeds cold and moist in the refrigerator and these gave good germination after 2 year storage.


Many seed sellers keep on selling seeds that are not viable anymore. This can only lead to disappointment with the buyer. The problem is that you cannot see how old a seed really is and that it is difficult to know how a seed is actually stored. When buying seeds from 'recalcitrant' species (see list below) use reliable sources and common sense. When somebody offers 'fresh' seeds of Asimina triloba / pawpaw in June you know that is nonsense.


Below is a list of seeds that I consider 'recalcitrant' and should be sown soon after harvesting (or directly stored cold AND moist in the refrigerator by 41 degrees Fahrenheit / 5 degrees Celsius). Of course there are many more species whose seeds are 'recalcitrant' but with the species below I got first hand experience.


== Actinidia arguta + kolomikta / Kiwi Vine

== Amelanchier species / Serviceberry / Snowy Mespilus

(many sources say that seeds of Amelanchier species can be stored cold and

dry but my experiences with stored seeds are not very good)

== Araucaria araucana / Monkey Puzzle Tree

== Aesculus species / Horse Chestnut

== Asimina triloba / Pawpaw

(Fresh seeds stored cold and moist in the refrigerator for 1 year gave good

germination)

== Carpinus species / Hornbeam

(many sources say that seeds of Carpinus species can be stored cold

and dry but my experiences with stored seeds are not very good)

== Carya species / Hickory

== Castanea species / Chestnut / Chinquapin

== Celtis species / Nettle Tree / Hackberry

== Clematis species

== Cornus controversa, macrophylla, walteri

(in contrast: Cornus kousa seeds gave good germination after 3 years cold

and dry storage)

== Daphne species

== Decaisnea fargesii / Blue Sausage Shrub

== Diospyros lotus + virginiana / Persimmon

== Eriobotrya japonica / Loquat

== Euonymus species / Spindle Tree

== Fagus species / Beech

== Ilex species / Holly

== Juglans species / Walnut

== Laurus nobilis / Bay leaf

== Lindera species / Spicebush

== Magnolia species

== Mahonia species

== Nyssa species / Tupelo / Sour Gum / Black Gum

== Paeonia species / Peony

(Dry stored seeds of Paeonia species come in a state of 'deep dormancy').

== Pseudolarix amabilis / Golden larch

== Quercus species / Oak

== Sassafras albidum

== Schisandra species / Magnolia vine

== Staphylea species / Bladdernut

== Symplocos paniculata / Sapphire Berry

== Tetracentron sinense

== Zanthoxylum simulans / Szechuan Pepper

(Seeds from my own shrub gave poor germination after dry and cold storage

for one year in the refrigerator)

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