The best catalpa planting location is an open, full-sun spot with room to spread. Set it well back from your house, walkways, and septic lines. This tree grows big and drops a lot of litter. So where to plant catalpa comes down to space. Give it room to shed flowers, leaves, and long pods onto lawn or mulch. Pick a spot clear of patios and driveways from the start. You cannot move a catalpa once it takes hold.
A catalpa messes up the ground under it in three waves. In late spring it drops showy white flowers. Through summer and fall it sheds huge, heart-shaped leaves the size of your hand. Then long, bean-like seed pods hang on and fall through winter, some stretching a foot or more. You want all of that landing on grass or a mulch bed, not on a pool, a car roof, or a stone patio. Cleanup is quick on a lawn and a real pain on hardscape.
Plan for the tree's full size, not the little sapling in your hand. A mature catalpa reaches 40 to 70 feet (12 to 21 meters) tall with a 20 to 50 foot (6 to 15 meter) spread. Those figures come from NC State Extension and the Nebraska Forest Service. The wood is brittle and sheds branches in high wind and ice. That is why clearance from your house, sheds, fences, and power lines matters so much. Look straight up before you dig and make sure no wires cross the spot.
A good catalpa planting location starts with full sun, though it will take partial shade. Six or more hours of direct light gives you the heaviest bloom and a strong, even shape. The extra light also helps the wood harden off. That cuts down on weak, snap-prone limbs. In deep shade the tree grows leggy and thin, and it flowers far less. A wide, sunny lawn or an open field edge suits it well.
The good news is that catalpa is not fussy about soil. It handles wet, dry, alkaline, and poor ground that most trees cannot stand. That makes it a strong pick for a low, damp corner where nothing else will grow, like a soggy back edge of the lot or a spot near a ditch. If you have a problem patch that stays wet, a catalpa may be the tree that takes to it at last.
Give it room from your neighbors too. A catalpa's wide crown and litter do not stop at the lot line, so set it far enough in that limbs and pods stay on your side. Twenty feet from a fence is a safe start for a full-grown tree.
Keep the tree at least 20 to 30 feet (6 to 9 meters) from any wall or paved surface. Good catalpa spacing from house walls protects your foundation, gutters, and siding from falling limbs and heavy shade. Keep it well off the septic drain field too, since catalpa roots chase water and can work into buried lines. The same goes for water and sewer pipes running out to the street.
If the only sunny spot sits close to seating, pick a fruitless or low-fruiting catalpa cultivar. You get the big shade leaves without pods dropping on the table.
Walk the yard before you dig and look up as much as you look down. Find a sunny, open patch that sits 20 to 30 feet from the house and clear of wires, septic, and paving. Give a catalpa that kind of room and it will shade your yard for decades with almost no fuss. Rush the spot and you will fight its litter and limbs for years.
Read the full article: Catalpa Tree: Identification and Growing Guide
