Olive trees come from the Mediterranean regions where the summer is hot and dry and the winter is wet and mild. Commercial olives are cultivated and propagated by grafting because an olive seed will tend to revert to a wild ancestor and produce small, hard fruits. Raising olive trees from seed may not produce a good harvest, but the tree can still find a place in the landscape as an ornamental. Olive trees can survive down to 12 degrees F for short periods of time.
Clean all the fruit off a fresh olive seed; rub the seed with wet sand to remove all traces of the olive meat. Use fresh olives; pickled and processed olives are not good for germinating.
Soak the seeds in a jar of water for 20 days before planting, change the water in the jar every day. Alternately; rub the seed on sandpaper until the surface of the seed is broken. Pre-treatment of the hard olive seeds increases germination rates.
Fill an 8-inch pot with a mixture of equal parts seasoned manure, clean sand and potting soil. Make a 1-inch deep hole in the center of the pot and place the seed into the center of the hole. Push soil over the seed and add water until the soil mixture is damp to the bottom of the pot.
Put a clear plastic bag upside down over the lip of the pot and fasten it with a rubber band. Remove the bag every three days and apply water if the soil feels dry to the touch. Put the pot in a greenhouse or window where it will get filtered sunlight. Keep the seed above 55 degrees F. The seed will germinate in about three months.
Remove the plastic bag when the seedling emerges. Keep the seedlings in a greenhouse or covered porch for the first three winters. Transplant it outside in the spring. Plant olive trees in an area with full sun and some wind protection.