Quaking aspen trees have pale bark, grow to between 60 and 80 feet tall and are famed for propagating themselves through suckers. Suckers are new trees that grow out of the lateral root of the old tree. The process continues until whole groves of quaking aspens are formed. Sometimes, however, suckers grow where you do not want them, but you can learn to transplant them to a new location.
Find a sucker from the mother tree in early spring. Follow an exposed root to any aspen seedling you see. Smaller suckers will be easier to transplant because they will have a smaller root system.
Use a shovel to dig around the sucker. Try to get as much of the root system as you can incorporated into the root ball. Cut the lateral root from the mother tree with the spade. Remove the sucker and wrap the roots with the original soil remaining in burlap. Water the root ball through the burlap with a hose to keep the soil moist until transplant, which should occur as soon as possible.
Prepare the transplantation site. Quaking aspens thrive best in full sun with moist, well-drained soil conditions. Dig a hole as deep as the root ball is high and twice its width. Use two shovelfuls of organic compost and work it into the soil for enrichment.
Unwrap the root ball of the sucker and place it into the prepared hole. Refill the hole around the roots with soil and pack it down around the base of the sucker tree. Place a 2- to 3-inch layer of mulch down and build a small mound around the tree for water retention.
Keep the transplanted sucker moist, but not soggy, while it takes root. In porous, sandy soils and hot weather, this might mean watering every other day. In more moist soils and hot weather, you can probably water only every three to four days. As the tree begins to grow, gradually decrease watering frequency to once a week, then once every two weeks in drier weather. Decrease watering frequency even more in winter months when the tree becomes dormant.