Planting a Tree in the Arizona Desert

A tree planted correctly will outlive the person who planted it. A tree planted poorly, too deep, in the wrong season, with circling roots, often struggles for years and fails early. Here's how to give a new tree the best possible start in the low desert.

Plant in Fall, Not Summer

In the low desert, October and November are the ideal planting window. Cooler air keeps the canopy from frying while warm soil lets roots establish through winter and spring, so the tree is anchored and growing before its first brutal summer. Spring is a workable second choice. Planting in June or July gives a tree the worst possible welcome: maximum heat stress with no established roots to support it.

Dig Wide, Not Deep

The most important rule of the planting hole:

• Width: dig the hole two to three times wider than the root ball. Roots spread outward, not down, so loose soil around the sides helps them get established.
• Depth: only as deep as the root ball, no deeper. The top of the root ball should sit at or slightly above the surrounding grade.

Planting too deep is a slow killer. It buries the root flare (where trunk meets roots), keeps the bark wet, and suffocates roots. If anything, err on the high side.

Don't Over-Amend the Backfill

It's tempting to fill the hole with rich potting soil or compost, but in desert planting this backfires. A pocket of fluffy amended soil inside hard native ground acts like a bathtub, it holds water, discourages roots from venturing into the surrounding soil, and can drown the tree. Backfill with the native soil you dug out. You want roots to adapt to the real ground they'll live in.

Check for Circling Roots

Before the tree goes in, inspect the root ball. Nursery trees that have been in their containers too long often have roots circling the pot. Left alone, these can eventually girdle and strangle the tree. Gently tease apart or score circling roots so they grow outward.

Build a Watering Basin and Water In

Form a shallow soil berm around the planting area to create a basin that holds water over the roots. Water the tree in thoroughly at planting to settle the soil and remove air pockets. For the first year or two, a new tree needs frequent water while it establishes, then you gradually transition it to the deep, infrequent schedule that builds a strong root system.

Stake Only If You Have To, and Loosely

Counterintuitively, most newly planted trees don't need staking, and a tree that's allowed to sway a little develops a stronger, tapered trunk. Stake only if the tree can't stand on its own or the site is very windy, and then:

• Use two stakes outside the root ball with loose, flexible ties that let the trunk move.
• Place ties low enough that the top of the tree can still flex.
• Remove the stakes after one growing season. Stakes and ties left on too long girdle the trunk and produce weak, dependent trees, a leading cause of monsoon blow-downs.
• Remove the nursery stake that came zip-tied to the trunk.

Mulch (Away From the Trunk)

A 2–4 inch layer of mulch over the root zone conserves moisture, moderates soil temperature, and suppresses weeds. Keep it pulled back a few inches from the trunk, mulch piled against the bark traps moisture and invites rot.

Pick the Right Tree First

All of this assumes you've chosen a species suited to your space and soil. If you haven't yet, start with our guide to the common trees of the West Valley. And for large specimen trees, soil prep, or a professionally designed planting, our landscaping services cover installation done right the first time.

This guide is part of the TCGS Tree Care Wiki. Need hands-on help? Book a tree care assessment with our certified arborists.