Plants for the Wasatch Front and northern Utah valleys
Valley heat, bench cold, and alkaline soils along the Wasatch, and why Park City is not Salt Lake City's plant list.
Northern Utah looks like one metro area from an airplane and like several climates from a garden. Utah State University Extension’s planting-date table puts an average last spring frost at the Salt Lake City airport on April 26, and at Logan’s USU station on May 7.
The same agency’s table puts Logan’s Southwest Farm at May 23. A 2019 USU note lists Park City at a last frost around June 9 and about 92 frost-free days, and Heber around June 11. Those are not one plant palette.
A red yucca that is routine in a hot Salt Lake parking strip is a gamble in a Park City snow year. This page is the valleys and benches. The high valleys should borrow from the mountain calendar and from the hardier end of the high plains list.
USU’s own writing on the state’s fickle climate is the horticultural point. Cold air drains, so a bench stays milder than a creek bottom a short distance away, which is why orchards sit on benches.
Urban pavement adds heat. A downtown Salt Lake bed and a pasture edge in the same county are different assignments. Ask a neighbor with the same landform, not a neighbor with the same ZIP code.
Soils and water before species
Wasatch soils are often clay, often alkaline, and sometimes salty, especially where irrigation has been heavy for a century or where a new lot was built on subsoil. The alkaline soil page is the test. Do not start with a plant that needs acid ground.
Iron chlorosis on a soft maple is as common a sight in a Utah parkway as it is in Denver. CSU’s susceptibility list is not a Utah publication, and the chemistry it describes is the same chemistry USU gardeners see. Prefer plants with a local record over a catalog of eastern shrubs.
Water is irrigation water. The valleys were built on it. A low-water planting still needs establishment water, and it needs a valve that is not the lawn.
Drip and xeriscaping are the method. Utah rainwater rules are not Colorado’s barrel statute.
Check the state water agency before you build storage. Do not import a Front Range how-to across the state line.
Trees and shrubs that fit the valleys
Bigtooth maple (Acer grandidentatum) is the native maple of the canyons and a far better conversation than a silver maple, which chloroses. It still wants a reasonable root zone and a deep, infrequent drink while it establishes.
Gambel oak (Quercus gambelii) is the native oak of the benches and foothills, a small tree or a large thicket depending on how it is grown. It handles the climate and it handles being itself, which includes holding brown leaves and sending up shoots. Plant it where that habit is welcome.
Curl-leaf mountain mahogany (Cercocarpus ledifolius) and the lower, broader mountain mahogany (Cercocarpus montanus) are native shrubs for dry slopes and well-drained beds. They are not foundation shrubs to shear. Utah juniper (Juniperus osteosperma) belongs on dry ground and is too often imitated with a water-hungry ornamental juniper under a sprinkler, which then thins and browns. If you want the look, give the plant the drainage and the low water, not a lawn schedule.
For a hotter valley bed, many of the Front Range sun perennials also perform: blanketflower, penstemons with drainage, sunset hyssop, and grasses such as blue grama in full sun. They are regional Western plants, not automatic Wasatch natives. That is fine if you say so.
Apache plume and chocolate flower are more at home in the hotter, southern parts of the state than on a cold bench.
In Cache Valley, lean on the hardier penstemons, the native maples and oaks, and grasses, and be cautious with ice plant, which rots under snow and winter wet.
Benches, inversions, and the fruit reminder
A bench site is the gift USU describes: cold air slides off, bloom is less often lost, and a marginal shrub has a chance. A hollow behind a solid fence undoes the gift.
When you plant, stand outside on a clear, still dawn and see where the frost sits. Put the tender experiment on the bench side of the house. Put the native oak where you can water it the first two years and then let it live.
Fruit trees are a Wasatch tradition and a Wasatch heartbreak, depending on the spring. The mechanism, midwinter thaw and spring frost on early bloom, is the chinook and fruit-bud page. Codling moth is ordinary in Utah valleys.
Plan on sanitation and on extension’s current timing if you want clean apples. The plant list on this page will not solve an insect that arrives every June. The apple page names that limit.
Invasive habits to refuse
Russian olive and tamarisk have already cost the region’s river corridors. Do not add them to a yard because they are “tough.” Myrtle spurge escapes foothill gardens. Tree of heaven spreads.
A tough plant that seeds into the canyon is not a xeriscape success. USU and county weed programs publish current noxious lists. Check them before you accept a free shrub from a neighbor’s overgrown lot.
Lawns can be smaller. The same buffalo grass and blue grama logic on the lawn page applies in full sun in the valleys, with the same shade warning. Many Utah lawns are tall fescue or bluegrass on irrigation.
Shrinking them, and fixing the spray that hits the sidewalk, saves more water than a new species you will not establish. A parking strip in full sun is a grass-and-penstemon planting, not a ribbon of turf.
A valley bed and a bench bed
In a hot Salt Lake or Utah County yard: bigtooth maple or Gambel oak for structure if you have the space, mountain mahogany or a well-drained native shrub mass, blue grama, blanketflower, a penstemon, and a gravel mulch only where drainage-loving plants sit. Chips elsewhere. Irrigation on a separate valve for two summers, then a deep soak when a drought is actually a drought.
On a cold bench or in a town with a June last frost: drop the ice plant and the red yucca, keep the oak and the penstemons that are known hardy, and treat anything labeled “for Salt Lake heat” as a wall experiment, not as the hedge. The Utah calendar is the planting-month companion. It shows why a single April weekend cannot be the planting weekend for both Logan’s campus and a high valley.
Checklist
- Separate valley heat from bench and high-valley cold before you choose species.
- Prefer bigtooth maple and Gambel oak over silver maple on alkaline ground.
- Give juniper and mountain mahogany drainage and low water, not a lawn schedule.
- Establish new plants, then back off.
- Refuse Russian olive, tamarisk, and myrtle spurge.
- Put fruit on a bench, not in a hole, and read the frost-on-bloom pages before you buy an apricot.
- Check a current noxious-weed list.
- Use the USU frost table for your own town. The airport is not the foothill.
Sources
- USU Extension, Suggested Vegetable Planting Dates for Utah, including the city last-frost column.
- USU Extension, Fickle Climate Keeps Gardeners Guessing, for bench versus valley and the Park City figures.
- USU Extension, Wasatch Front vegetable planting dates.
- CSU Extension, Iron Chlorosis of Woody Plants, for the chemistry shared by these alkaline soils.