Seed from these species will produce poor germination unless given varying lenghts of moist cold pre-treament.  The length of this cold pre-treatment varies between 14-20 weeks, depending on the species.  The precise length can usually be obtained from the seed merchant's catalogue.

If large quantities (in excess of 1Kg) of seed are needed, the seed should be mixed in equal volume with a stratification compost prepared with equal proportions of sieved sand and sieved sphagnum peat.  The peat helps to reduce compaction and increases the moisture and oxygen retaining qualities of the medium.  Sieving the constituents helps prevent clumping and waterlogging and promotes a more homgeneous mix.  The compost must be moist.  A useful rule of thumb for obtaining the correct moisture/air content is to add water until a consistency is reached which will just produce a drop of water when a handful is squeezed tightly in the fist..  The mixture is laid in beds up to 12" deep, kept moist and turned weekly.  The temperature should be in the range of 1-5C and the best results will be produced if it is allowed to fluctuate as it does naturally.

For smaller quantities of seed the most practical method is to place the seed stratification mixture in a polythene bag, and keep it in the refrigerator or cold transplant store at 1C.  Treating small quantities using the method recommended for large amounts can lead to excessive fluctuation in moisture levels.

Sorbus species are slightly different in that if possible the seeds should be stratified as soon as they are extracted from the berries and before they are allowed to dry out.  This will normally be from late August for Sorbus aucuparia and until late October for most other Sorbus species.  In addition it has been demonstrated that for dried stored seed of Sorbus species there is a more synchronous germination when they are given a two week warm pre-treatment in the range of 20-30C before the cold pretreatment at 1-5C.

Freshly harvested Sorbus seed may begin to germinate as early as January.  If this is too early, the process can be halted by storage at -3C for up to six weeks.  However for all species once seedling emergence has taken place the temperature must not be allowed to fall below 0C.

For sowing the pre-treated seed shouild be laid in seed trays approx 3" deep, kept moist and turned regularly to examing it for germinating seed.  THe Rootrainer cells should be filled to within 1/4" of the top.  Germinated seed should be carfully pricked out one per cell.

THe smallest Rootrainer for this species is the Sherwood.  This will satisfactorily accomodate all sizes of plant grown in 1 year of those species witn the exception of Surbus aucarpia and possibly Sorbus intermedia.  Sorbus aucarpia if sown early is capable of groing to well over 1m in height by late summer. Sorbus intermedia should reach at least 60cm by September and so both these species should be grown in Fleet Rootrainers if large plants are required.