Aspen is in general propagated from root cuttings. Cuttings should be taken in early spring after the threat of frost. They should be collected from roots of vigorous healthy adult trees. The roots taken should have a diameter of a half inch to one inch in diameter, with a length of about one foot. The roots should then be handled carefully not to allow them to dry out. By wrapping them in damp news paper and placing them in a plastic bag for transporting.
When all collection is done it is best to plant them as soon as possible. Plant the root cuttings in a box with light compost peat mix about 4 inches deep. Cover the cuttings with about 2 inches of peat compost mix.
The root cuttings should start to sucker or develop new shoots these herbaceous shoots can then be used to propagate the new trees. Herbaceous cuttings should be taken after the shoot has grown to about 4 inches. The cuttings should then be treated with a rooting hormone 1000 ppm IBA quick dip solution or .2% IBA talc powder. The cuttings then can be place in a perlite peat mix of 50/50. They then will have to placed in a high humidity, temperature controlled environment. Do not allow them to dry out! The temperature should not exceed 75ºF. After several weeks Rooting should have taken place. The plants can then be put outdoors to harden off. This can be done in either a cold frame or a shaded side of a building
The aspens can then be transplanted into bigger pots where they can develop into larger trees. These trees can be planted the following year or that fall after growth has stopped.