The Lombardy Poplar is a fast grower, growing about six feet in a year. If conditions are right, it can grow up to 12 feet per year. It is of the Salicaceae family. The genus is Populus and the species is nigra. Lombardy Poplar grows best in full sun in zones 4 to 9. Though it does prefer full sun, it will tolerate some shade.
Check the Height Clearance
The first thing that should be considered before planting a Lombardy Poplar tree is its height. It can grow to over 100 feet, and like all large trees, it's thirsty. Lombardy Poplar roots will seek out water aggressively, so it should not be planted near water lines or sewage lines.
If a line has a leak or is a septic leech line, the roots will seek out the excess moisture and grow into the lines, causing big problems, since the lines will have to be dug out and replaced. Roots will also need to be dug out quite far back, but they will just grow back towards the water source, unless the water line was leaking and is now fixed. The roots will generally not bother PVC or metal lines, as long as they are not leaking.
Poplar trees can be planted as close as four feet apart, as they grow tall and narrow. The poplar can live up to 80 years or more, and it makes a great fenceline tree or a windbelt. Poplars do not need much fertilizer, but a soil test should be performed at least once every three years. If the soil is low or missing nutrients, fertilize Lombardy Poplar with a nutrient-specific fertilizer.
To propagate a Lombardy Poplar, use a semi-woody stem cutting. Dip the stem cutting in rooting compound and plant it in amended soil. Once the plant becomes established in its pot, it can be transplanted outside. Dig a planting hole twice the size of the root ball and as deep as the soil in the container. Center the poplar in the planting hole and backfill with soil.
Whenever you plant a poplar, it's a good idea to create a watering ring around the perimeter of the planting hole. The watering ring will help water the outside roots, and hopefully help keep them from creeping to find their own water source. Mulch the tree with compost or pulverized mulch. Mulching will also help keep the soil moist.
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