Protecting outdoor plants from frost damage can seem daunting, but with some simple preparations and care, you can help your plants survive the cold. Here are the most effective ways to protect your outdoor plants when frost threatens.
Monitor the Weather and Temperatures
- Check your local weather forecast regularly so you can anticipate upcoming frost and freezing conditions. Pay close attention to predicted overnight lows.
- Invest in a thermometer designed specifically for monitoring outdoor temperatures. Place it near your garden so you can easily check temperatures outside.
- Frost often occurs when temperatures dip below 32° Fahrenheit. Be especially vigilant when overnight lows are forecast to drop into the 20s.
Choose Frost-Tolerant Plants
- Select cold-hardy plant varieties that can better withstand frosty conditions. Some options include kale, pansies, ornamental cabbages and kales.
- If planting frost-sensitive varieties like tomatoes, peppers or basil, be prepared to provide extra protection when frost threatens.
Prepare Your Garden Beds
- Insulate the soil around plants by spreading 2-3 inches of mulch such as pine straw, leaves, wood chips or compost. The mulch helps prevent frost from penetrating deep into the soil.
- Clear any dead or decaying vegetation around plants, which can harbor moisture and cold.
- Consider raised garden beds, which drain and warm up faster than planting directly in the ground.
Cover Plants Overnight
- Cover plants with frost blankets, burlap or old sheets when frost is imminent. Secure the edges with weights like stones or stakes so the covers stay in place.
- Cloches, row covers and cold frames are useful for protecting low-growing or tender plants. Just be sure to allow ventilation during the day.
- For potted plants, move containers together and cover with a plastic tarp, secured so it doesn’t blow away.
Water Wise
- Avoid overwatering plants before a frost, which can saturate soil and increase frost damage. But don’t let plants dry out completely either.
- Water in the morning before a frost night so foliage has time to dry out before temperatures drop. Damp foliage is more susceptible to freezing.
Warm Up the Soil
- Place black plastic sheeting or landscape fabric on top of beds to warm the soil beneath. Remove them during the day to allow sunlight through.
- Lay electrical heating cables beneath mulch, on top of soil. Use a thermostat to control automatic on/off.
Choose Warm Spots
- Plant against south-facing walls or fences, which absorb more heat during the day.
- Avoid low areas and the bases of slopes, which tend to collect cold air. Plant on higher ground instead.
- Plant in raised beds oriented east-west to maximize sun exposure.
Be Ready on Frost Nights
- Prepare covers and cold protection items ahead of time so you can place them quickly as needed overnight.
- Set alarms to wake you up and check on plants during cold snaps. Be ready to implement emergency measures if needed.
- After a frost, uncover plants in the morning but leave protection handy in case of another cold night.
Protect Tender Growth
- Prune away excessive tender new growth in fall, which is vulnerable to cold damage. Avoid late-season fertilizing.
- Mound soil, mulch or leaves around the crowns or bases of plants for insulation.
- Spray anti-desiccant sprays which form a protective wax coating on foliage. Do not apply oil-based products.
Provide Warmth
- Place incandescent lights among plants, which give off a small amount of heat. Use CFLs or LEDs for ambient lighting only.
- Safely use a portable heater near plants, positioned off the ground and away from combustibles. Do not leave operating unattended.
- String outdoor patio lights above plants. The tiny bulbs emit a surprising amount of warmth downward.
Choose Cold-Hardy Perennials
Some perennials are more resistant to frost and cold temperatures than others. Good choices include:
- Ornamental grasses
- Russian sage
- Sedums
- Daylilies
- Lavender
- Coral bells
- Catmint
- Yarrow
- Bee balm
- Peonies
- Iris
- Lungwort
- Hellebore
Should You Harvest Before Frost?
It depends on the vegetable:
- Frost-sensitive crops: Pick green tomatoes, peppers, beans, cucumbers, squash, eggplant and melons before frost.
- Cold-tolerant crops: Carrots, beets, turnips, parsnips and other root veggies can be left in the ground under mulch until later harvest.
- Leafy greens: Kale, spinach, lettuce and other greens often become sweeter after a light frost. Enjoy them well into winter.
FAQs About Protecting Plants from Frost
How do I know if my plants are damaged by frost?
Look closely at foliage and tender growth for signs of damage. Blackened, wilted or mushy leaves/stems indicate frost kill. Scrape away outer layers – if inner tissues are still green and firm, plants may recover.
Can you water plants to protect against frost?
No, watering just before a frost can create surface ice and exacerbate freezing damage. Water 1-2 days prior to a frost so soil retains warmth better.
Should I prune plants before winter?
Remove spent flowers, dead wood and weak stems in fall. But avoid trimming evergreen hedges or pruning shrubs you want for winter structure until spring.
Will a late frost kill my plants?
A late spring frost can damage warm-season annuals and tender new growth on trees/shrubs. Cover or bring inside to protect. Established perennials and shrubs typically recover from late frost damage.
When should I start taking frost precautions?
Be ready for first fall frost anywhere from 4-6 weeks before your average first frost date. Protect plants anytime lows are forecast to drop into the 20s or lower overnight.
Which method works best for protecting container plants?
Group containers together and cover with a lightweight fabric row cover or frost blanket. Make a teepee of stakes over plants and drape plastic sheeting or tarp over the framework, sealing edges with weights.
Conclusion
Protecting your plants from frost doesn’t have to be complicated or time-consuming. With some simple planning and preparation using the tips above, even cold-sensitive plants can make it through frosty nights unscathed. Pay attention to weather forecasts, cover plants overnight, remove dead foliage, and provide a little extra warmth on the coldest nights. With this proactive care, your garden will stay vibrant well into the winter months.