Poplar trees are among the fastest-growing of all deciduous trees, and can grow up to 8 feet in a year. Poplars have high value for agriculture and forestry, as they can stabilize precarious stream banks, provide windbreaks for crops, prevent soil erosion and provide effective shelter for birds and wildlife. In the home landscape, poplar trees can provide shade in a hurry, while you're waiting for other slower-growing trees to mature. Poplars require large amounts of water early on, but once established, their needs are minimal.
Water poplar trees deeply the first year, using a drip irrigation system. If you don't have drip irrigation, allow a hose to trickle slowly at the base of the trees. From April to July, water poplar trees approximately 3/4 to 1 inch every week. In July and August, when the trees are in their fastest growth phase, water the trees about 1 1/2 inch every week. After the first year, the poplar's root system will be established, and normal rainfall is usually enough, although the trees will benefit from an occasional watering during periods of drought.
Pull weeds and grass around the planting area. Weeds and grass will compete with the poplar tree for available soil nutrients and moisture, slowing the tree's growth. Weeds and grass can also harbor insects and promote disease.
Spread a thick layer of organic mulch in a 24-inch band around the base of the tree, but leave 8 inches uncovered immediately around the trunk, as mulch piled up against the trunk can invite pests and disease. A 4- to 5-inch layer of organic mulch such as shredded bark, pine needles, straw or chopped leaves will help conserve moisture, and will maintain an even soil temperature.