When fall frosts hit your garden, it’s only natural to worry about how best to protect your vulnerable plants. Many homeowners assume that keeping soil dry during cold snaps is safer, but professional landscapers point out that a counterintuitive approach can actually help protect tender perennials from frost damage.

Here’s why watering deeply before a freeze can help your garden stay healthy in cold temperatures.

Why Keeping Garden Soil Moist Can Improve Heat Retention

Understanding how soil interacts with temperature is key to shielding your yard from frost damage. Outdoor and landscape designer Chris Turner, who owns Elevate by Design, points out a valuable technique for weathering sudden cold snaps.

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“This is a lesser-known tip, but moist soil actually holds heat better than dry soil does,” Turner says. “So if you can water the perennials heavily the day before frost comes, it keeps the temperature more stable overnight when the frost arrives.”

Moist soil acts as a natural thermal insulating layer, absorbing solar heat throughout the day and radiating that warmth back up into the air around your plants during freezing night hours. This simple practice stabilizes overnight temperatures right at the root zone where tender perennials need it most.

How to Time Your Pre-Freeze Watering

To make the most of this protective strategy, timing is essential. Turner advises scheduling your heavy watering session during the daytime hours before the frost arrives, ensuring the ground absorbs the moisture fully before temperatures plummet.

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Avoid combining this method with the use of plastic sheeting, which can damage tender plants if it comes in contact with the foliage.

Prepping the earth ahead of time gives your delicate perennials a reliable buffer against harsh overnight temperature swings.

Sources:

• Chris Turner, Outdoor and landscape designer, owner of Elevate by Design

This article has been adapted from 6 Proven Ways to Protect Tender Perennials From Frost by Ashley Zlatopolsky

Related: Professional Gardeners Explain How to Start a Compost Pile in Autumn: 6 Steps to Composting Success