With the changing of the seasons, however, comes the age-old game of chicken that gardeners play with the weather — determining the best time to plant our tender annuals. A daring tomato planter may throw caution to the wind and set out starts early, only to have an unexpected frost wipe them out.
A cautious planter will be sure to get those sensitive sprouts out well after the threat of a freeze, but they will have to watch their neighbor pick ripe, red tomatoes while their own plants have only begun to push out buds. And, as summer gives way to fall, the harvesting season for those hard-won fruits is hampered by the return of the cold.
But we are not powerless. Gardeners have invented a wide range of options over the centuries (and learned how to protect plants), from simple leaf shelters to ice-defying cold frames. To help you get started on what could be your best gardening season yet, here’s a handy list of tips on how to protect plants from frost and keep your garden growing for as long as possible.
How to Protect Plants From Frost
So, what can you do to protect your frost-sensitive plants? During the colder hours of the night, wrap them in a blanket. The soil absorbs heat from the sun during the day. Covering plants in the evening captures the heat that the soil re-radiates into the night.
It is worthwhile to expend the effort required to protect plants from a late spring freeze and an early fall frost. After all of your hard work of sowing seed, raising young seedlings, and preparing your garden, it’s easy to lose tender plants on cold nights and miss out on the harvest.
There are several methods for protecting plants from frost. Using a combination of techniques is the best approach and will provide the most comprehensive protection for frost-sensitive plants.
- Covers: Covering plants is the most common and effective method of frost protection. Bedsheets, blankets, drop cloths, or burlap sacks should be used as covers, and they should be staked or weighted to the ground to prevent gaps. The heat from the ground will be trapped under the cover, keeping the plant warmer and reducing frost damage, but stakes or spacers should be used to ensure the cover does not crush the plant’s foliage. You can use your Metal garages or Carports to protect your plants. As the temperature rises in the morning, remove the covers to allow the plants to breathe and recover.
- Mulch: A thick layer of dark-colored mulch can help retain soil warmth, and the dark color improves the mulch’s ability to absorb solar radiation, which it will then release back around the plant as the temperature drops at night. To help reduce frost damage, wood chips, bark, straw, pine needles, and fallen leaves can be used as winter mulch. Mulch layers should be at least 2-3 inches thick for maximum effectiveness. Mulch can be applied over the entire plant of low, mounding plants that go dormant in winter, but it should be removed before spring growth begins.
- Clustering: Container plants should be clustered together to help them survive a cold spell and to reduce the risk of frost damage. The humidity released by the leaves of plants will help keep them frost-free, and the more plants that are clustered together, the better their chances of survival. If a hard frost is a forecast, move container plants to a sheltered area, such as inside a garage or shed, and wrap a blanket around the pots or cover the entire group of plants for extra protection.
- Watering: Damp soil retains heat better, and plants that are well-watered are more resistant to cold damage. Begin gentle watering 2-3 days before the frost is predicted to help plants absorb as much water as possible, but do not water them if a complete freeze is predicted because wet soil is more likely to heave during a freeze, causing root damage. Succulents should also not be watered before a frost or freeze because they naturally hold a lot more water.
- Heat Lamps: Heat lamps can help protect plants from frost in extreme cases. A 100-watt bulb can be used to keep plants warm, particularly if it is placed under a cover to protect a plant cluster or larger plants like saplings. However, make sure the lamp does not come into contact with the plants, or it may cause burns. Non-LED light strings can also be used to raise the ambient temperature around a plant and protect it from frost if a single bulb is not available.
What Causes Frost?
To protect your gardens from the ravages of frost, it’s a good idea to understand what frost is and what conditions can cause it. Frost occurs when water vapour in the air condenses to form dew, which is then cooled to the freezing point — usually at night — while you’re daydreaming about those bumper tomato harvests. Gardeners are plagued by these specific conditions in the early spring and late fall.
However, this is not a town-wide event. Frost can fall in patches across the landscape, covering one garden while barely touching the garden next door. The shape of the land is one of the factors that contribute to this. Because cold air weighs more than warm air, any depression or low-lying area in the ground can allow the chill to pool and collect like an invisible puddle.
On cold nights, these areas can easily become “frost pockets.” Furthermore, areas that slope north or have something blocking the morning light are the last to feel the sun’s warm touch every day. On ideal mornings, they are more likely to be glistening with frost. To protect frost-sensitive garden plants, create a barrier between their living surface and the dew that wants to settle on them.
What Materials Should You Use for Plant Frost Protection?
Plastic can be used to protect plants from frost, but it is not the most effective or efficient material. In fact, the horticultural experts at Green Impressions advise against it. Plastics, such as vinyl and traditional camping tarps, are not breathable, allowing moisture to accumulate inside.
The plastic can actually stick to the leaves depending on its thickness, and when the material is removed in the morning, the beautiful plants you expect to see will be stuck to the plastic sheeting. And, if the temperature drops sufficiently, the increased moisture trapped beneath the non-breathing plastic will pose a greater threat to the health of your plants and increase the likelihood of premature death.
Green Impressions recommends natural fabrics for frost protection instead of plastic, such as a cotton or linen towel or blanket, an open burlap bag, or even newspaper. This is especially true for clients who live along the Northeast Ohio lakeshore in Avon, Avon Lake, Lorain, Bay Village, Lakewood, and Sheffield, where the lake’s humidity is higher.
Use of fabrics to protect plants.
These natural fabrics allow moisture to escape while still protecting your potted plants and landscaping flowers from harsh weather by preventing freezing air from coming into direct contact with the moisture under the fabric and on the plants themselves. Meanwhile, bed sheets are effective for covering large plants and shrubs, as well as young sprouts, and newspaper can be used on low-growing foliage but will not stay on top of large plants as well.
There are coverings available for purchase that are specifically designed to protect your plants from frost and freezing weather conditions. While these pre-designed coverings may be more visually appealing than the impromptu methods mentioned above, all of these options are effective at protecting your trees, plants, and landscaping flowers from frost.