Rio Grande cottonwood

Populus deltoides wislizeni

Family:: Salicaceae
Elevation:: 3,000 ft – 7,000 ft
Bloom:: Mar – Apr
Region:: Southwest

The great gallery tree of the bosque — massive, spreading cottonwoods whose golden fall color lines the Rio Grande. A true riparian species that needs a water table or a ditch, not a dry yard.

Care · tuned to the Southwest

Water

The exception to high-desert dry gardening: it needs abundant, deep water and naturally grows where roots reach groundwater. Do not plant it expecting xeric care — it will decline and drop limbs.

Sun & exposure

Full sun.

Soil

Deep alluvial soil along rivers and acequias; tolerates periodic flooding.

In the Southwest

Fast, brittle, and short-lived for its size — limbs shed in wind, so keep it away from structures. Female trees release the summer 'cotton.' Best appreciated in the bosque rather than a small lot; plan for a big, thirsty, messy tree if you plant one.

Common problems & fixes

Aphids and sticky honeydew — heavy infestations coat leaves and surfaces in residue and sooty mold
Fix — Hose off colonies, avoid overfertilizing, and tolerate them as a seasonal nuisance on strong trees.
Brittle limb drop — fast, weak wood sheds large branches in monsoon winds
Fix — Prune structurally while young for good branch angles and remove overextended limbs before storm season.
Cotton litter, borers, and mistletoe — female trees shed cotton; stressed trees get borers and mistletoe
Fix — Plant cottonless male cultivars, keep trees vigorous with deep watering, and prune out mistletoe and dead wood.

Pets & toxicity

Non-toxic.

Easy to confuse with

Lanceleaf cottonwood (Populus x acuminata) — narrower leaves, higher elevation
Siberian elm (Ulmus pumila) — invasive, often confused from a distance

Sources

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