Salt-Tolerant Shrubs and Grasses for Curb Strips and Driveways

For the strip along the street and the edges of the driveway, use plants that university trials and extension lists rate as salt-tolerant. For shrubs, go with junipers, mugo pine, rugosa rose, sumac, potentilla, alpine currant, spirea and ninebark. For ornamental grasses, use switchgrass, little bluestem, Karl Foerster feather reed grass or blue fescue. For turf, use fine fescues (creeping red, hard, sheep and Chewings fescue) instead of straight Kentucky bluegrass. Keep arborvitae, boxwood and red twig dogwood back from the pavement.

On a golf course, the cart path edges and the strip along the entrance road take the most abuse. Your curb strip is the same kind of ground. Picking the right plant fixes most of it, so here's how.

Why the curb strip kills the wrong plants

Salt gets to plants two ways, and they cause different damage.

Spray. Passing cars throw salty slush onto branches and needles. You see it in early spring as browned needles, dead buds and dieback on the side facing the road. University of Wisconsin Extension says most spray damage happens within 60 feet of the road, though sensitive plants can show it 1,000 feet or more from a major highway.

Soil. Plow piles and meltwater soak salt into the root zone. That damage builds slowly, over several years, and Wisconsin puts most of it within 30 feet of the road. The plant gets thinner each spring and leafs out later, and nobody connects it to salt until half of it is dead.

Some plants handle one kind of salt better than the other, so look at where yours will sit. A shrub at the curb gets spray plus a plow pile on top. A shrub 10 feet up the driveway mostly gets runoff from the salt you put down yourself.

Shrubs that hold up

These show up as salt-tolerant on the northern extension lists I trust (Wisconsin, UMass, Penn State). All of them are hardy across most of the northern half of the country, but check the hardiness zone on the tag.

Evergreens:

• Junipers. Chinese, common, creeping (Juniperus horizontalis) and eastern red cedar all made the lists. Creeping juniper is the workhorse for a curb strip because it stays under a foot or two and plows can roll over it. Penn State names eastern red cedar as one of the evergreens that hold up to deicers.
• Mugo pine. It's on the UMass, Wisconsin and Penn State lists. Buy a dwarf cultivar if it's going near the curb, because the species can get big.
• Inkberry holly. Penn State lists it. It works for a softer look near the house end of the driveway.

Deciduous:

• Rugosa rose. It's the classic beach-and-roadside rose, and UMass lists it as tolerant. It's thorny, so plant it where nobody walks.
• Sumac. Fragrant sumac (Rhus aromatica) stays low and spreads, and staghorn sumac fills a wide strip. Both are on the Wisconsin list.
• Potentilla (shrubby cinquefoil), alpine currant, spirea and ninebark. These are the reliable mid-size shrubs. They're cheap, easy to find and on the Wisconsin list.
• Lilac. Penn State and Wisconsin both list it. Meyer lilac (Syringa meyeri) stays compact enough for a driveway edge.
• Bayberry (Myrica pensylvanica). It's tough and gets wide, so it fits a bigger strip.

Viburnums are mixed. Wisconsin lists nannyberry, arrowwood and American cranberrybush as tolerant. UMass puts viburnum on its sensitive list. If you want one near the road, plant nannyberry and keep it out of the plow pile.

Ornamental grasses

These are the most forgiving plants you can put in a curb strip. You cut them to the ground every spring, so any salt burn on the old blades gets cut off with them. Wisconsin Extension lists these as salt-tolerant:

• Switchgrass (Panicum virgatum). It's native, stands up through the winter and comes in 3 to 6 foot cultivars.
• Little bluestem (Schizachyrium scoparium). It's native, stays around 2 to 3 feet and turns copper in fall.
• Feather reed grass (Calamagrostis × acutiflora, usually 'Karl Foerster'). It's upright and narrow, so it's good where space is tight.
• Blue fescue (Festuca glauca) and blue oat grass (Helictotrichon sempervirens). Both are short clumps, and you can see past them when you're backing out.
• Fountain grass (Pennisetum alopecuroides) and northern sea oats (Chasmanthium latifolium).

Northern sea oats likes some shade and moisture, so use it on the shady side of the drive and not the hot, open strip.

Tip from the course: keep anything taller than about 30 inches away from where the driveway meets the street. You need to see cars and kids coming. Short grasses or creeping juniper go at the corners, and the tall stuff goes in the middle of the strip.

Lawn grass for the curb strip

This is where most lawns go wrong. Kentucky bluegrass is a great grass almost everywhere else in the yard. On salty roadsides it fails. The University of Minnesota tested 75 cool-season turfgrasses for roadside salt tolerance, and its turf program reports that bluegrass "is not very salt tolerant on Minnesota roadsides."

The grasses that survived were the fine fescues: slender creeping red, strong creeping red, hard, Chewings and sheep fescue. The salt-tolerant roadside mix that came out of that work is mostly fine fescue, with about 20% bluegrass kept in so the sod holds together. Fine fescues also want less fertilizer and water than bluegrass. That suits a curb strip nobody waters.

Alkaligrass ('Fults', 'Salty') used to be the go-to salt grass, and it handles salt well. Minnesota found it establishes slowly and gets crowded out of mixes over time, so it's no longer the backbone of their recommendation.

In practice, seed the strip with a fine fescue blend or a mix labeled for roadside salt tolerance. Expect it to look a little finer and more blue-green than the bluegrass in the rest of your lawn. That's normal.

Plants to keep away from the pavement

These show up on the sensitive lists:

• Arborvitae. Penn State calls it very salt-sensitive even though people plant it along roads all the time. A row of eastern red cedar does the same screening job. (If you already have arborvitae, see snow load on arborvitae and yews for the other winter problem.)
• Boxwood, red twig dogwood, eastern white pine, Norway spruce, hemlock, sugar and red maple, littleleaf linden. All are on the UMass sensitive list.

Wisconsin says to keep salt-sensitive plants 30 to 40 feet from city streets and 60 to 100 feet from highways. On a city lot you can't always do that. If you can't, plant something tolerant in the front row and keep the sensitive plants up by the house.

Planting this fall

Shrubs and container grasses: Early October is fine for container shrubs across most of the northern US, as long as you get them in a few weeks before the ground freezes and keep them watered until it does. See planting trees in fall and watering before the ground freezes. Ornamental grasses settle in better from spring planting in the coldest zones. If you plant them now, mulch the crowns.

Grass seed: Fine fescue needs warm enough soil to germinate. In much of the north it's now late to seed the strip and get it established. Check whether it's too late to overseed and soil temperature. If you missed the window, dormant seeding in November works well on a curb strip. Freeze and thaw work the seed in, and it comes up in spring before the weeds.

Set the bed up to drain. Salt that can't drain out stays in the root zone. Grade the strip so meltwater runs off, and don't build a soil berm that holds slush against the plants.

Spring cleanup when salt gets in anyway

Tolerant plants still do better if you flush the salt out:

• Water heavily in early spring. Wisconsin says to apply at least 6 inches of water to push salt below the roots. Penn State says 6 inches removes about half of what built up. Spread it over several deep soakings, not one flood.
• Gypsum on salty clay. Penn State recommends 40 lbs per 1,000 sq ft in spring. It helps on heavy clay, where sodium wrecks the soil structure. It won't do much on sand.
• Prune spray-burned tips after new growth starts, so you can see what's actually dead.

The road salt damage post covers the full fix. Cutting down on the salt itself helps too, so switch your driveway ice melt and shovel before you salt.

Before you buy

1. Stand at the curb and figure out where the plow pile lands. Plant creeping juniper, grasses or nothing at all there.
2. Measure how far each bed sits from the street. Within about 30 feet, plant only from the tolerant lists.
3. Read the tag for the cultivar's mature height. Keep the corners at the street under about 30 inches.
4. For turf, buy a fine fescue or roadside salt-tolerant blend, not straight bluegrass.
5. Put "6 inches of water on the curb strip" on your March calendar now.

Related: Deer Damage to Shrubs in Winter: Prevention That Works

Sources (6)

• University of Wisconsin Extension: Winter Salt Injury and Salt-tolerant Landscape Plants
• Penn State Extension: Minimize Deicer Damage with Salt Tolerant Plants
• UMass Extension: Impact of Salts on Plants
• University of Minnesota Turfgrass Science: Salt-Tolerant Roadside Grasses
• University of Minnesota: Salt tolerance of 75 cool-season turfgrasses for roadsides
• UVM Extension: Managing Salt in the Landscape

Photo: Andropogon scoparius - little bluestem - 53323389116 by Matt Lavin, CC BY-SA 2.0.