Trees use seeds as a principal means of establishing their next generation in the natural world. Seeds serve as a delivery system for the transfer of genetic material from one generation to the next. This fascinating chain of events - the formation of seed to dispersal to germination - is very complex and still poorly understood.
Some trees can easily be grown from seed but, for some trees, it may be much quicker and easier to propagate them from cuttings. Seed propagation can be a tricky process for a number of tree species. A small seedling can be very tiny and delicate when first germinated and often require much more care than a cutting. Seed collected off tree hybrids or grafted stock can be sterile or the tree be off character from the parent.
Seeds collected from a pink dogwood will most likely flower white.
What Stops Seeds From Germinating
There are a number of important reasons a seed refuses to germinate under artificial conditions. Two major causes for unsuccessful tree seed germination are hard seed coats and dormant seed embryos. Both conditions are species specific and every tree species has to subject the seeds to unique conditions to assure germination. Treating the seed properly is necessary before germination occurs and a seedling can be assured.
Seed scarification and stratification are the most common methods of seed treatment and they will increase the chances of seed or nut germination.
Scarification and Stratification
Scarification - The hard protective coating on some tree seed is nature's way of protecting the seed. But hard coats on some hard seeded species actually inhibit the germination of the seed because water and air can not penetrate the hard coating.
Interestingly, many tree seeds require two dormant periods (two winters) before the protective coating breaks down enough to germinate. The seeds must lay on the ground completely dormant for one full growing season, and then germinate the following growing season.
Scarification is the artificial way to prepare hard seed coats for germination. There are three methods or treatments that will usually make seed-coats permeable to water: (1) soaking in a solution of sulfuric acid, (2) soaking in hot water or immersing the seed for a short period in boiling water, or (3) mechanical scarification.
Stratification - Many dormant tree seeds need to be "after-ripened" before they can germinate. This is the most common cause of seeds failing to germinate. If the seed embyro produced by a tree is dormant, it must be stored at the proper temperature and in the presence of abundant supplies of moisture and air.
Stratification is the process of mixing the seed in a moist (not wet) medium like peat moss, sand or sawdust, then placed in a storage container and stored in an area where the temperature is controlled at a low enough level to "ripen" the seed. This storage is usually over a definate period of time at a specific temperature (around 40 degrees F.)
More on Germination of Common Trees