What Are the Mesquite Tree Growing Zones?

Mesquite is a desert tree, yet the zones it can grow in stretch from the hot Southwest up into places with real winters. There is no single answer, because the mesquite at a nursery may be a native North American species or a South American one, and the two differ a lot in cold tolerance. So the first question for anyone planting one is which mesquite it is, and the second is how cold the winter gets where you live.

Mesquite Growing Zones by Species

A USDA hardiness zone is a map band based on the average coldest winter night, and each zone is 10°F colder than the one above it.

The sources differ because native mesquite ranges reach as far north as southwestern Kansas, western Oklahoma, and southern Utah and Nevada.5Fire Effects Information System. Prosopis glandulosa Zone 6b is the edge, where a hard winter can damage or kill a tree.

To find your own zone, look up your ZIP code on the USDA hardiness map. Then read the nursery tag closely, because “mesquite” alone doesn’t say which kind you’re buying. Prosopis glandulosa is honey mesquite, and Prosopis chilensis is Chilean. Hybrids sold as Chilean or “thornless” behave like South American types when it comes to cold.

In zone 7 or colder, pick honey or screwbean mesquite over Chilean. In zones 9 to 11, any common type survives the cold, so choose by size, thorns and look. Zone 8 can suit Chilean mesquite, but a rare hard freeze can still hurt it.

A zone number is a starting point, not a guarantee. The map uses the average of each year’s lowest temperature, so about half of winters dip below your zone’s stated low. Your own yard can also run warmer or colder than the map says: paved areas, south-facing walls and city centers hold heat, while open lawns and valley floors often run colder. Zone ranges also say nothing about how long a freeze lasts or how fast temperatures drop, and both affect whether a tree is hurt.

Surviving the cold is only part of it. Mesquite wants full sun and well-drained soil, so a spot that qualifies by zone can still fail if water stands around the roots.

How Much Cold Each Mesquite Can Take

Dieback means twigs and branch tips die back from the ends. Young trees and South American types show it first. Wait until spring growth starts before pruning dead wood, so you can see what is truly dead. Even a tree killed back to the trunk may resprout from the base.

The low number isn’t the whole story, because length of freeze matters too. In freeze tests, Chilean, Argentine and other South American mesquites handled several brief freezes around 23°F but not a freeze lasting 12 hours.10Forest Science. Screening Prosopis (Mesquite) for Cold Tolerance Native North American honey and velvet mesquite came through the 12-hour freeze with only moderate damage.11Forest Science. Screening Prosopis (Mesquite) for Cold Tolerance A long, still cold night is therefore more dangerous for a South American mesquite than a quick dip to the same low.

A still, clear night with no wind or cloud cover tends to hold the cold longest near the ground, so a mesquite in an open yard can face a more severe night than the forecast low suggests. When a freeze is coming, watch how many hours it will stay below freezing, not only the lowest number.

When a hard freeze is forecast, cover a young or South American mesquite in a borderline zone before dark with frost cloth or an old blanket that reaches the ground, and remove it the next morning once temperatures rise. Plastic touching the leaves or twigs can conduct cold and trap moisture, so cloth is the better covering. Watering dry soil a day or two before a freeze helps it hold more heat overnight, but that is no substitute for covering a tender tree.

In the wild, honey mesquite only grows where the average coldest night stays above about -5°F and there are at least 200 frost-free days a year.12Fire Effects Information System. Prosopis glandulosa Even a hardy honey mesquite needs a long warm season, not just survivable winters.

Helping a Mesquite Through Winter

How well a mesquite handles cold depends on its condition going into winter.13Danger Garden. This weeks favorite, the Mesquite Tree… Heavily fertilized and watered trees tolerate cold worse than trees given less water and no fertilizer late in summer.14Danger Garden. This weeks favorite, the Mesquite Tree… So stop fertilizing by midsummer and cut back watering as fall approaches. Late fertilizer and extra water push soft new growth that hasn’t hardened before the first frost, and tender tips are the first to be killed.

Ease off water gradually. Stretch the gap between waterings as days shorten and nights cool, rather than stopping suddenly. If fall and winter stay completely dry, keep giving a deep soaking now and then, particularly to young trees, since a very dry root zone is also stressful.

Mesquite also protects itself by leafing out late. Honey mesquite rarely leafs out until after the last spring frost or until days pass about 11.5 hours of light.15US Forest Service Research and Development. Prosopis glandulosa, honey mesquite Leaf-out can shift by as much as 6 weeks from one year to the next.16US Forest Service Research and Development. Prosopis glandulosa, honey mesquite Trees from northern populations tend to leaf out later than southern ones.17US Forest Service Research and Development. Prosopis glandulosa, honey mesquite Once buds open, new twigs and leaves usually finish growing in about 6 weeks.18US Forest Service Research and Development. Prosopis glandulosa, honey mesquite A bare mesquite in April is often normal, not dead.

To check a bare tree, scratch a twig with a fingernail; green underneath means it is alive. Be patient into late spring before deciding a tree died.

In a borderline zone, siting helps. Plant near a south- or west-facing wall that holds heat, and avoid low spots where cold air settles on still nights. Buy a native species from a local source, since it may be adapted to local winters. Protect young trees in their first winters, when they are most vulnerable.

Water, Heat and Soil Needs

Honey mesquite thrives in heat over 100°F.19Winrock International. Honey Mesquite: A Multipurpose Tree for Arid Lands It can live with very little rain and has been found in Death Valley, which gets about 2 inches a year.20Winrock International. Honey Mesquite: A Multipurpose Tree for Arid Lands In the wild, though, it usually grows where it can reach groundwater.21Winrock International. Honey Mesquite: A Multipurpose Tree for Arid Lands Its roots can tap water 13–20 feet down.22Ecology. Diurnal and Seasonal Water Relations of the Desert Phreatophyte Prosopis Glandulosa (Honey Mesquite) in the Sonoran Desert of California

Water depth also controls size. Velvet mesquite grew tall, over 40 feet, with large leaves only where groundwater was within about 16 feet of the surface.23Journal of Arid Environments. Response of velvet mesquite to groundwater decline As water dropped to 60 feet and below, trees became stressed and lost almost half their canopy.24Journal of Arid Environments. Response of velvet mesquite to groundwater decline

For a landscape tree, water deeply and infrequently so roots grow down, not shallowly. Young trees need regular water the first year or two. Frequent shallow watering makes fast, weak growth that can blow over.

Soil is rarely the problem. Mesquites handle a wide range of soils, including low-nutrient, salty and alkaline ground.25Weed Management Guide. Mesquite – Prosopis species That’s because mesquite is a legume, and bacteria in its roots let it draw nitrogen from the air.26Journal of Arid Environments. Influence of mesquite (Prosopis glandulosa) on soil nitrogen and carbon development: Implications for global carbon sequestration Nitrogen builds up in the soil under mature mesquites.27Soil Science Society of America Journal. Soil Properties in a Mesquite‐Dominated Sonoran Desert Ecosystem So mesquite rarely needs fertilizer.

Drainage matters more than richness. Standing water around the roots for long periods can rot them. Heavy clay that stays soggy after rain is a bigger problem than sandy or rocky ground, so avoid planting where water pools.

Where Mesquite Grows Naturally

Mesquite is a thorny legume shrub or tree from dry regions, and most of its 40-plus species come from South America.28Texas Natural Resources Server. Mesquite ecology The two main U.S. species are honey mesquite and velvet mesquite, growing as anything from low shrubs to 25-foot trees.29Texas Natural Resources Server. Mesquite ecology Honey mesquite grows mainly in Texas, New Mexico and northern Mexico, reaching into California, Oklahoma, Kansas and Louisiana.30Texas Natural Resources Server. Mesquite ecology Velvet mesquite grows mainly in southern Arizona, plus California and northern Mexico.31Texas Natural Resources Server. Mesquite ecology Planting the species native to your region is usually the safest choice.

In practice, Texas and New Mexico gardeners usually do best with honey mesquite, and southern Arizona gardeners can choose velvet. To find out what grows near you, look at undeveloped land, washes and roadsides, since mesquites growing there without help are already suited to your climate. Local native plant societies, county extension offices and regional nurseries can tell you which mesquite is native where you live.

Honey mesquite usually has long, narrow leaflets and a pale tan bean pod, while velvet mesquite has leaflets covered in fine hairs that give a soft, grayer look. Chilean mesquite is a South American species, not native to the U.S., so a tree with that name at a nursery was brought in as a landscape plant. A tag with the Latin name is more reliable than the common name, since sellers use “mesquite” loosely.

Is Mesquite Invasive

Mesquite and other woody plants have grown much denser in southwestern grasslands over the past 150 years.32Annual Review of Ecology and Systematics. Shrub Invasions of North American Semiarid Grasslands Without regular fire, prairies turn into shrubland and even woodland.33PLJV. What Are the Mesquite Tree Growing Zones? Grassland fires used to burn back young woody seedlings before they matured, while the grasses regrew from their roots. Once fires were put out, mesquite seedlings could grow past the point where a grass fire would kill them. Heavy grazing also removes grass that would fuel a fire, which helps shrubs gain ground.

Overseas, mesquite now grows in 129 countries and is considered one of the world’s worst invasive woody plants.34AoB PLANTS. Prosopis: a global assessment of the biogeography, benefits, impacts and management of one of the world’s worst woody invasive plant taxa In Western Australia, livestock and kangaroos spread seed and turned grassland into mesquite stands.35Journal of Arid Environments. Spatial and temporal rates and patterns of mesquite (Prosopis species) invasion in Western Australia Mesquite pods are sweet and eaten by cattle, deer and other animals, and the seeds pass through the animal and are dropped in manure with their own fertilizer. Check local rules before planting outside its native range; in some countries mesquite is a regulated weed that can’t be planted.

A city lot is different from open range, because a yard is small, watered and mowed, so most stray seedlings are easy to remove. The risk grows where the yard borders open land, a ranch or a wash, since seeds can move into places you don’t control. Rake up fallen pods, and pull seedlings while they’re small, before deep roots form.