TL;DR
Get garden gear delivered free with Prime
- Fast, free delivery on millions of items
- Prime Video, Amazon Music and more included
- Member-only deals all year
An early frost can damage tender annuals, dahlias and warm-season vegetables before the growing season has ended. Garden experts cited by Homes & Gardens recommend covering vulnerable plants with breathable fabric, supporting covers above delicate foliage and removing them after temperatures rise.
Tender annuals, dahlias and warm-season vegetables are among the plants most at risk when an early frost arrives, according to gardening experts cited by Homes & Gardens. The report advises gardeners to monitor overnight forecasts and protect vulnerable plants before the first frost, helping limit damage to flowers and crops that are still growing.
Landscape designer Kat Aul Cervoni, founder of Staghorn Living, says she starts watching forecasts when overnight temperatures reach the mid-30s Fahrenheit. Frost can form on plant surfaces even when the official air temperature remains a few degrees above freezing. Signs of damage may include foliage that is darkened, limp, water-soaked or translucent, later turning brown or black.
For tender plants, Cervoni recommends lightweight frost cloth or horticultural fleece; a bedsheet can serve as a temporary cover, much like floating row covers. Drape the material to the ground and secure its edges so it can hold warmth rising from the soil. She advises against placing plastic directly on foliage, because contact can transfer cold to leaves and covered plants may overheat after sunrise.
Dahlias and warm-season crops need particular attention. Cervoni says a frost can blacken dahlia foliage and end flowering. Tomatoes, peppers, eggplants, cucumbers, squash and beans are also vulnerable, as they generally do not tolerate freezing temperatures. For delicate blooms, stakes or hoops can hold fabric above stems and flowers. Covers should go on before temperatures drop at night and come off the next morning after temperatures rise above freezing.
Protecting Flowers and Late Crops
An early cold snap can end a garden’s productive or flowering period before plants have naturally reached the end of their season. That matters most for late-season blooms and edible crops, where a single frost may damage foliage, reduce harvest prospects or stop flowering. A timely cover can provide short-term protection, though it cannot make frost-sensitive plants cold-hardy.
The advice also points to differences within the same garden. Cervoni notes that cold air settles in low areas, so plants at the bottom of a slope may face greater risk than those higher up. Walls can retain warmth, while wind and cloud cover affect how frost develops. Gardeners may need to prioritize plants according to both species and location.
Products Worth Considering
LEVOIT Vital 100S-P Smart Air Purifier with Washable Pre-Filter
Dyson Car+Boat Cordless Handheld Vacuum
Samsung 48-Inch S90H OLED 4K Smart TV (2026)
As an affiliate, we earn on qualifying purchases.
Forecasts and Garden Microclimates
Homes & Gardens presents the advice as fall garden guidance, when warm daytime weather can obscure the risk of colder nights. The report notes that frost risk is not determined by a single air-temperature reading: plant surfaces can cool enough for frost even when the forecast remains a few degrees above freezing. Local conditions and microclimates influence exposure, making the garden’s position relevant alongside the forecast.
Kate Copsey, author of New York & New Jersey Gardening, says a frost cloth, sheet or cold frame can usually protect plants when air temperature is above 30°F. She describes frost between 30°F and 32°F as less severe and often spotty. These figures are expert guidance in the report, not a guarantee for every plant, covering material or site.
The source identifies five broad categories for attention: tender annuals, late-season flowers, warm-season vegetables, tropical or tender container plants, and other frost-sensitive plants. Its supplied material gives examples and detailed advice for the first three categories, but does not provide the full supporting discussion for the remaining two.
“I start paying attention when overnight temperatures are forecast to fall into the mid-30s, since frost can form on plant surfaces even when the official air temperature is a few degrees above freezing.”
— Kat Aul Cervoni, landscape designer and founder of Staghorn Living
Local Frost Risk Varies
The report does not identify a specific frost event or forecast for a particular location. When a frost will occur, how low temperatures will fall and which gardens will be affected depend on local forecasts, terrain and microclimates. The advice does not promise that covers will prevent all damage, and the supplied source material does not detail the final two plant categories or all recommended protections for them.
Frost tolerance also varies by plant and growing conditions. The source distinguishes frost from chilling injury: basil and coleus may show cold-related damage before temperatures reach freezing. Gardeners should not treat a single temperature threshold as a guarantee that every plant is safe.
Check Forecasts Before Nightfall
Gardeners can check local overnight forecasts and inspect vulnerable plants, particularly those in low-lying areas and exposed beds. If frost is forecast, apply breathable covers before temperatures fall, secure them to the ground and use supports where fabric could crush flowers. Remove covers after temperatures rise above freezing so plants do not remain covered longer than needed or overheat in daylight.
For dry beds, Cervoni says watering earlier in the day before an expected frost may help because moderately moist soil retains heat better than very dry soil. The next practical signal is the local overnight forecast; the report gives no specific date or regional warning for an upcoming frost.
Key Questions
Which plants does the report identify as vulnerable to early frost?
Examples include coleus, impatiens, begonias, zinnias and basil, as well as dahlias and warm-season vegetables such as tomatoes, peppers, eggplants, cucumbers, squash and beans.
When should I cover plants?
The experts advise watching overnight forecasts as temperatures enter the mid-30s Fahrenheit and putting covers on before temperatures fall in the evening. The exact risk depends on the plant and local conditions.
What kind of cover can I use?
Lightweight frost cloth, horticultural fleece or a bedsheet can be used, with edges secured at ground level. Avoid placing plastic directly against leaves, and remove covers after temperatures rise above freezing.
Can one part of a garden be colder than another?
Yes. The report says cold air tends to settle in valleys and at the bottom of slopes, while areas near walls may stay warmer. These local differences are known as microclimates.
Source: homesandgardens.com
