How to protect plants from frost starts with timing, insulation, and smart plant choices, all tailored to your local climate and landscape. With a few strategic steps before the first cold snap, you can dramatically cut winter losses and keep your beds, borders, and containers ready to bounce back in spring.​

Know Your Frost Risk

To understand how to protect plants from frost, start by learning your USDA hardiness zone and your area’s average first and last frost dates; these benchmarks help you decide when to plant, when to cover, and when to stop fertilizing tender growth. The USDA map was recently updated for the first time in over a decade, reflecting a general warming trend but also more volatile swings, which means late cold snaps can still surprise unprotected landscapes.​

Most gardeners should begin active protection when forecasts dip to around 32°F, since many plants suffer visible damage once temperatures fall to about 30°F or lower, especially if cold lasts several hours. Research on frost injury in fruits and ornamentals shows that critical damage thresholds can be just a few degrees below freezing, depending on growth stage, so a “light frost” that seems minor can still kill buds and new shoots.​

How to Protect Plants from Frost

1. Insulate Roots with Mulch

One of the most reliable ways to protect plants from frost is to insulate the root zone with mulch before repeated freeze–thaw cycles begin. A 2–4 inch layer of organic mulch such as shredded bark, leaves, pine straw, or hay helps stabilize soil temperatures, guards against heaving, and reduces erosion over winter.​

Moist, mulched soil can hold more heat than dry, bare ground, which gives roots a small but meaningful temperature buffer on the coldest nights. For container plants, topping the pot with mulch and clustering containers together, then wrapping or boxing them, can protect vulnerable roots that would otherwise be exposed to lethal cold penetrating the upper inches of soil.​

2. Protect Plants from Frost Using Covers

When planning how to protect plants from frost on short notice, covers are your first line of defense for shrubs, perennials, and annuals that cannot be moved. Lightweight materials such as frost cloth, bed sheets, blankets, burlap, or row-cover fabric trap radiant heat from the soil, creating a pocket of slightly warmer air around the foliage.​

Always drape covers so they reach the ground and are anchored at the edges; an open bottom lets cold air flow in and warm air escape. Avoid resting plastic directly on leaves, since contact points can still freeze and burn; instead, use stakes, hoops, or patio furniture to hold the cover above the plant canopy and remove it the next day once temperatures rise above freezing.​ Here is a blog detailing proper use of covers.

3. Water Wisely Before a Freeze

It feels counterintuitive, but watering ahead of a hard frost is a proven tactic in how to protect plants from frost and freeze damage. Moist soil absorbs and slowly releases more heat than dry soil, so a deep watering 1–3 days before a predicted freeze can raise overnight soil temperatures around the root zone.​

Focus on trees, shrubs, and new plantings, and water early enough in the day that foliage can dry before temperatures drop, which reduces the risk of ice forming directly on leaves. Skip this step if the ground is already frozen or waterlogged, since oversaturation in winter can stress roots and negate the benefits of added warmth.​

Prioritize Placement and Plant Selection

Over the long term, smart design decisions do as much to protect plants from frost as any emergency cover or heat source. Placing tender plants near south-facing walls, stone patios, or other heat-retaining hardscape elements can raise local nighttime temperatures slightly and reduce the odds of freeze damage.​

Choosing more cold-hardy shrubs, evergreens, and perennials for exposed areas is another powerful strategy; for example, many evergreen species maintain structure and color through winter while tolerating temperatures that would injure more tender ornamentals. In fact, guidance for new plantings often emphasizes matching varieties to zone limits, because a mismatch can turn a single freak cold night into a season’s worth of losses.​

Know When Conditions are too Extreme

Even with the best techniques for how to protect plants from frost, there are limits to what covers and mulch can handle. Many resources note that simple coverings lose effectiveness once air temperatures drop below about 28°F, especially if readings stay subfreezing for more than five hours.​

Studies of frost damage indices suggest that visible injury becomes almost certain once tissue experiences temperatures several degrees below typical thresholds, and severe cold can penetrate the top inch or two of soil and kill sensitive plant parts outright. During those rare extreme events, the highest-value or most tender plants are safer indoors in a garage, shed, or basement until the worst cold passes.

How Can We Help Protect Your Plants from Frost

We, at Walnut Ridge, are here to help with any questions you may have, and are happy to help with winter plant selection and mulching, as well as reviving any part of your landscaping that needs it come spring! Our seasonal landscape maintenance services are here to ensure your landscape stays healthy through every season of the year.