Trees and shrubs · Houston
How to plant a new tree and avoid transplant shock
Hole width, circling roots, backfill, water, and mulch decide whether a new tree takes or sits in shock through its first Houston summer.
When to plant
Any time it is not freezing. There is no narrow planting window in Houston.
Plant in the ground rather than leaving a tree in a pot. A pot holds a thin layer of soil with ambient air all around it, so it dries out fast in the heat. The ground insulates the root ball and holds moisture in.
The hole
Dig a hole two to four times the width of the root ball and only as deep as the root ball. Roots spread sideways rather than down, so width matters more than depth. A hole dug deeper than the ball lets the tree settle below grade as the loose soil compacts.
Backfill
Tree & Shrub Mix is the blend built for this: sandy loam topsoil, Casco Compost and humus, mixed so a young tree gets stability and a root system that goes into the ground. Mix the soil you removed 1:1 with it before it goes back in. An organic starter fertilizer such as MicroLife Multi-Purpose 6-2-4 can raise the nutrient level in that backfill.
Before the tree goes in, slide it out of the container and check the roots. If it is root-bound, cut vertically along the sides and across the bottom of the ball to break circling roots.
Set the ball so the tree is level. Fill until the soil is even with the top of the root ball. Stake it with T-posts or another anchor so wind does not rock it while roots grow.
Water and mulch
Keep the soil moist around the tree for the first year without drowning it. Water deeply once a week rather than a little every day, because shallow watering keeps roots at the surface.
Spread 2 to 4 inches of Aged Native Mulch. On a new planting, carry it all the way out to the edge of the canopy: the roots run to the canopy edge and a little beyond, and that is what gives the tree its stability. Keep it off the trunk itself and off any exposed roots, which are part of how the tree breathes.
The mulch is not feeding the tree. It holds moisture and steadies soil temperature, and it adds humus to the soil as it breaks down. Compost is what adds nutrients.
One cubic yard of mulch covers about 100 square feet at 3 inches deep, or about 80 square feet at 4 inches. Run your own numbers in the Yard calculator.