It is important to have a sterile growing medium. Most of your local gardening supply stores should offer a commercial soilless mix. There are many choices: Pro-Mix, Fafard, Sunshine are a few that are easily available. You may also make your own. A standard mix contains equal amounts of peat moss, perlite (and/or vermiculite - differing opinions out there on that!) and sand. Bark can be used instead of sand, coconut coir (more expensive) can be used instead of peat moss. Lots of choices out there so just Google: homemade soilless seed mix and do your research if you want to go the homemade route.
Primarily the best reason for using a soilless planting medium is that you can control any types of insects, diseases, bacteria, and weed seeds that are found in garden or potting soils.
Another reason is that it is a lighter soil. Garden soil is heavy and without drainage which can be hard on delicate new root systems. The lightness of the soilless mixture can also be beneficial when transplanting or moving your young plants later on.
Nutritional value of the soil is another factor - the right balance of Ph. and other minerals in important to getting the right start for your seeds. DO AVOID mixes though with "continuous feeding".
From U of Illinois Extension
Link & Photo Below:
Well, this one is pretty hard to define in a brief space. Again, our goal is to give you good simple definitions without delving into the science as there are a lot of sites out there with better information than I can write.
Basically you are trying to imitate what happens to the plant in winter. You are trying to coax the seed embryos to wake up from their sleepy, dormant state.
I found a pretty good blog: From "An Introduction to Stratification" blog.
What you are doing with stratification is a pretreatment to begin the seed germination process. Think of it as a “jump start” to the rush to spring growth.
Other terms you may encounter while reading up on the topic are “cold stratification” or “warm stratification.” There are differences.
The Garden Club of America's "Basic Plant Propagation Guide" defines stratification as the "after-ripening of the seed embryo and achieved by replicating a cold, wet winter.
There are various ways to do this - a simple way and one that will save space is to put your seed (according to type - don't mix different seeds together!) - in a sealed, labeled (date/type of seed) plastic bag filled with moist, vermiculite or sphagnum moss. You may also wrap the seeds in a damp paper towel. Neither of these should be soaking wet! Wring out your peat or your paper towel first. The bags with paper towels are flat and may be stacked on a shelf - just make sure there is good air circulation around the bags and don't put too many in a stack.
Time in the fridge (or in a well-insulated cold frame outdoors) varies from 1-6 moths. It is important that you research your particular seed.
Once through the stratification period, bring out and pot up in shallow containers.
Next post - where we have placed our little trays of seeds and hopes of germination soon!