Climate extremes and storms seem to increasingly dominate headlines. Drought, forest fires, hurricanes, and flooding are just a few of the weather-related crises we saw in the U.S. in the last few years.
Such weather impacts can wreak havoc on prized, irreplaceable, and otherwise long-lasting landscaping. While the simple solution is a return to natives, even natives or zone appropriate plants can suffer when the zone experiences extremes. The record breaking freeze in Texas and the blazing heat in Oregon last year damaged or killed otherwise healthy zone-appropriate plantings in just a matter of days.
According to a 2018 Yale School of the Environment paper, U.S. plant hardiness zones are moving north at 13 miles per decade. When the map was last updated in 2012, nearly half the country was upgraded to half a zone warmer than it had been in 1990. The Arbor Day Foundation says this affects which trees are right for planting. In 2015 it completed an extensive updating of zones and documented the shifts since 1990.
While maps shift, mature trees can’t shift with them. We can fertilize, prune, and keep them at optimum health to better weather adverse conditions, but ultimately our most valuable landscape elements must often just bear up. Which is why we need to give them a fighting chance. We need to pick the right trees for potentially wrong conditions. This is the era of the tough tree.
What makes a tough tree? One that is proven to best withstand nature’s onslaught. Turf perused university extensions and other reputable sources to create tree lists for weather extremes. Got a windy spot? Learn from Florida experts, who deal with hurricanes, a resilient choice that grows in your zone. If there’s a native that solves your problem, even better.
It should be noted that no tree is hurricane-proof or fireproof, but some are more “resistant” than others. Placement, other plants, and maintenance are equally important factors to consider beyond species. But we hope this provides a handy first reference for problem areas.
It’s no surprise the University of Florida Institute of Food & Agricultural Sciences (UF/IFAS) Extension has a whole website entitled “Trees and Hurricanes.” They even list trees with the least wind resistance: sand pine, Chinese elm, water oak, and laurel oak. While UF research showed that sand live oaks (Quercus geminata; Zones 8-10) are the most resistant to wind damage, other good choices include (numbers represent zones):
- Southern magnolia (Magnolia grandiflora) 7-9
- Live oak (Quercus virginiana) 7-10
- Bald cypress (Taxodium distichum) 4-10
Those somewhat resistant to storm damage include:
- Sweetgum (Liquidambar styraciflua) 6-7
- American holly (Ilex opaca) 5-9
- Sycamore (Platanus occidentalis) 4-9
- Swamp chestnut oak (Quercus michauxii) 6-9
- Spruce pine (Pinus glabra) 8-9
- Gumbo limbo (Bursera simaruba) 10b-11
- Tupelo or Blackgum (Nyssa sylvatica) 3-9
While not technically trees, sabal palm (Sabal palmetto; Cold hardy to 8a or b) are an excellent choice as well. Smaller ornamental trees like crepe myrtle and dogwood are also mentioned.
The Clemson Cooperative Extension Home & Garden Information Center has a list of salt tolerant plants for the South Carolina coast. Trees are rated high or moderate tolerance. High tolerance means a tree can handle direct salt spray. These include:
- Southern Red Cedar (Juniperus virginiana var. silicicola) 3-9
- Live Oak (Quercus virginiana) 8-10
- Southern magnolia (Magnolia grandiflora) 7-9
- Yaupon Holly (Ilex vomitoria) 7-10
Trees with moderate tolerance can grow beachfront adjacent, but should be sheltered. They include:
- American Holly (Ilex opaca) 5-9
- Loquat (Eriobotrya japonica) 8-10
First published in 2006, but reviewed in July 2020, Fire Resistant Plants For Home Landscapes, is a 48-page free downloadable guide to a diverse list of plants that are both fire resistant and attractive. Not just trees, the publication also covers ground covers, perennials, and shrubs and was produced by the Pacific Northwest Extension of Oregon State University, Washington State University, and the University of Idaho.
When it comes to conifers, ponderosa pine (Pinus ponderosa; Zones 3-6) and western larch (Larix occidentalis; Zones 4-7) are among the most fire-resistant due to their thick bark, which protects them from fire, and the high moisture content of their foliage.
The list of deciduous trees is long and includes:
- Amur maple (Acer ginnala) Zones 2-7.
- Bigleaf maple (Acer macrophyllum) Zones 5-9.
- Red maple (Acer rubrum) Zones 3-9.
- Horsechestnut (Aesculus hippocastanum) Zones 3-8.
- Red alder (Alnus rubra) Zones 4-7.
- Mountain alder (Alnus tenuifolia) Zones 5-9.
- Birch (Betula species) Zones 2-7.
- Western catalpa (Catalpa speciosa)
- Hackberry (Celtis occidentalis) Zones 3-9.
- Eastern redbud (Cercis Canadensis) Zones 4-9.
- Flowering dogwood (Cornus florida)
- Hawthorn (Crataegus species) Zones 3-9.
- European beech (Fagus sylvatica) Zones 4-7.
- Green ash (Fraxinus pennsylvanica) Zones 3-9.
- White ash (Fraxinus Americana) Zones 4-9.
- Thornless honeylocust (Gleditsia triacanthos var. inermis. cvs) Zones 3-9.
- Kentucky coffeetree (Gymnocladus dioicus) Zones 3-8.
- Walnut (Juglans species) Zones 4-9.
- Sweetgum (Liquidambar styraciflua) Zones 6-7.
- Crabapple (Malus species) Zones 3-9.
- Western or California sycamore (Platanus racemosa) Zones 7-10.
- Quaking aspen (Populus tremuloides) Zones 2-7.
- Chokecherry (Prunus virginiana) Zones 3-8.
- Canada red chokecherry (Prunus virginiana ‘Canada Red’) Zones 2-10.
- Oregon white oak (Quercus garryana) Zones 6-8.
- Pin oak (Quercus palustris) Zones 4-8.
- Red oak (Quercus rubra) Zones 3-8.
- Purple Robe locust (Robinia pseudoacacia ‘Purple Robe’) Zones 4-8.
- Mountainash (Sorbus aucuparia). Zones 3-5.
While these lists can provide ideas and starting points, reach out to your local University Extension for more specifics on “tough” trees in your area. And look for more to come on drought and flood-tolerant trees in Turf’s June issue focusing on Water.