Deicing salts are essential for keeping roads and walkways safe during winter, but they can have detrimental effects on your landscape. Understanding how these salts affect your plants and soil can help you take steps to protect your landscape. Here’s what you need to know and how to mitigate the damage caused by deicing salts.
Understanding Deicing Salts and Their Use
Deicing salts, primarily composed of sodium chloride (rock salt), calcium chloride, and magnesium chloride, are used to melt ice and snow. While effective for road safety, these salts can have harmful effects on landscapes. Sodium chloride is the most commonly used but causes the most significant damage to plants compared to alternatives like calcium chloride, which is less toxic though more corrosive to hardscapes.
Effects of Deicing Salts on Plants
Deicing salts can damage plants in several ways:
- Salt Spray: When vehicles pass, they can spray salty water onto nearby plants, causing leaf burn and twig dieback. Evergreens are particularly susceptible, with salt spray leading to needle browning starting at the tips.
- Soil Contamination: Salt can accumulate in the soil, disrupting the soil’s structure and affecting water uptake by plants. High sodium levels can break down soil aggregates, leading to compaction that reduces water infiltration and hinders root growth.
- Root Damage: High salt concentrations in the soil can cause dehydration and root damage, leading to stunted growth and plant death. Chloride ions can build up in plant tissues, causing direct toxicity that results in yellowing foliage and overall decline.
- Additional Physiological Impacts: Salts can mimic drought conditions by drawing water away from roots, and over time, they may disrupt nutrient absorption, including essential elements like calcium, potassium, and magnesium, exacerbating long-term health issues.
Symptoms of Salt Damage
Recognizing salt damage is crucial for timely intervention. Common symptoms include:
- Brown Leaf Margins: Leaves may develop brown, scorched edges, often progressing from the tips inward on evergreens.
- Stunted Growth: Plants affected by salt often show reduced growth and vigor, including smaller leaves and delayed bud break.
- Dieback: Twigs and branches may die back, especially on the side facing the road or walkway. In severe cases, plants may exhibit wilting during hot, dry summer conditions or premature fall color and leaf drop.
Preventative Measures
Preventing salt damage starts with proactive measures:
- Barriers: Erect physical barriers like burlap screens to shield plants from salt spray.
- Alternative Salts: Use less harmful deicing products, such as calcium magnesium acetate or sand, which are less damaging to plants. Mixing sand with salt at a 50:1 ratio can provide traction while minimizing plant exposure.
- Proper Placement: Plant salt-sensitive species away from roads and walkways to reduce exposure.
- Prompt Snow Removal: Shovel or clear snow as soon as possible to reduce the overall need for deicing salts, and avoid piling salted snow near plants.
- Anti-Desiccants: Apply anti-desiccant sprays to evergreens in fall to create a protective coating that reduces moisture loss from salt spray.
Mitigating Salt Damage
If your landscape has already been affected by deicing salts, these steps can help mitigate the damage:
- Leaching: In early spring, water the affected areas thoroughly to flush salts out of the soil. Ensure good drainage to prevent salt buildup, and apply water equivalent to about 6 inches over the root zone to effectively dilute concentrations.
- Soil Amendments: Add organic matter or gypsum to the soil to improve structure and reduce salt concentrations. Gypsum is particularly useful for counteracting sodium by helping to restore soil aggregation.
- Mulching: Apply a thick layer of mulch to help retain soil moisture and reduce salt spray contact with the soil. Mulch also minimizes evaporation, which can concentrate salts near the surface.
- Plant Replacement: Replace severely damaged plants with salt-tolerant species. Some hardy options include junipers, pines, and certain grasses.
- Soil Testing: Test soil for salinity levels before planting or amending to gauge the extent of contamination and guide remediation efforts.
- Rinsing: If feasible, gently rinse affected foliage with fresh water soon after salt exposure to remove residues before they cause further harm.
Salt-Tolerant Plants
Choosing salt-tolerant plants for areas prone to salt exposure can minimize damage. Here are a few examples, including both natives and hardy cultivars:
- Trees: Honeylocust, Norway maple, Austrian pine, elderberry (Sambucus canadensis), and coral honeysuckle (Lonicera sempervirens).
- Shrubs: Rugosa rose, sumac, bayberry, trumpet vine (Campsis radicans), and sea thrift (Armeria maritima).
- Perennials: Daylilies, hostas, sedum, catmint (Nepeta), creeping thyme (Thymus serpyllum), coneflower (Echinacea purpurea), and alkali sacaton grass (Sporobolus airoides).
Note that even salt-tolerant plants may show stress in extremely high concentrations, so combining them with other preventative strategies is ideal.
Winter Landscape Maintenance
Proper winter maintenance can also reduce the impact of deicing salts:
- Regular Inspections: Check your landscape regularly for signs of salt damage and take action promptly.
- Adjust Salt Usage: Use the minimum effective amount of deicing salts to reduce environmental impact. Avoid applications in late winter when plants are emerging from dormancy, as they are more vulnerable then.
- Protective Barriers: Install barriers around sensitive plants before the winter season.
Conclusion
Deicing salts are necessary for winter safety but can pose a significant threat to your landscape. You can protect your plants and soil from damage implementing these strategies to keep your landscape healthy and thriving, even during the harshest winter months.
