Avocados will sprout from seed and grow in Canada, but you'll still need to buy fruit from the market, since avocados do not flower in Canada's cold climate. Hardy avocado plants have been grown in Sidney and Vancouver. Though frost tolerant, they require protection in the winter to withstand prolonged freezing. Even with a greenhouse cover and artificial warmth in the winter, they do not normally produce fruit.
Avocados in Canada
Start with a ripe avocado: one that isn't hard, but yields to a squeeze and is a healthy green, without dark spots. Slice the skin lengthwise, and separate the halves. One will contain the large pit, or seed. Remove it, and enjoy the nutritious fruit!
Wash the pit clean under running water. Pat dry. Push three toothpicks 1/2 inch toward the center of the largest part of the seed. With the toothpicks resting on the rim of a container, immerse the fat side of the seed in an inch of water. Put the container on a sunny windowsill.
Keep watering. In three to six weeks, the seed will crack, and a sprout will appear. Roots will grow from the base in the water. When the sprout grows six inches, pinch the top two leaves off. New leaves and branches will grow in two to three weeks.
Plant your avocado tree in an 8 inch flower pot filled with new potting soil. Moisten the soil evenly, and make a hole in the center of the pot. Spread the avocado's roots, and cover them with soil. Leave the top half of the pit above the soil line, and press the soil down to eliminate air pockets.
Set the pot in a sunny window and keep the soil moist, but not wet. If the plant's leaves turn yellow, cut back on the water. Fertilize your plant with a balanced houseplant food every two or three weeks in the summer and six weeks in the winter. To encourage bushy growth, keep pinching the top two leaves off stems of six inches or more.
Repot your avocado as it grows—at least once every spring. Put it on a rolling base to make it easier to move into the sun and out of the cold. Avocados can grow 20 to 40 feet tall. Move your avocado tree outside in the summer, after all threat of frost is gone—it will thrive in the sun. Bring it inside if your winter is colder than 45 degrees Fahrenheit (7 degrees Celsius).