Mulberry seeds benefit from cold stratification. Stratification is a process of simulating natural conditions that the seeds must experience before germination can occur (if a seed germinates in the middle of winter it will die). In the wild, seed dormancy is usually overcome by the seed spending time in the ground through a winter period and having its hard seed coat softened up by frost and weathering action. This cold, moist period triggers the seed's embryo; its growth and subsequent expansion eventually break through the softened seed coat in its search for sun and nutrients.

• Get a handful or two of vermiculite, perlite or sterile compost (microwave compost in a plastic bowl for 3 minutes) then allow to cool.
• Add a little water to the mix. Should be moist but not wet
• Place in small ziplock bag
• Place in bottom fridge or in cold shed/outbuilding for 6-8 weeks 
• Spread bag contents on a tray of moist compost.
• Cover very lightly with compost or vermiculite
• Keep in a warm place 15-22c
• Seedlings should appear after 20-30 days
• Keep moist - best to place seed tray inside a waterproof container and water from the bottom
• Pot on as required