October 22, 2026

How cold can strawberry plants tolerate in bloom

Open strawberry blossoms take damage at about the freezing point of water. Tight buds still tucked into the crown survive a few degrees colder, and a dormant crown in midwinter survives far colder than either. In spring the open flower sets your limit, so treat any night forecast near freezing as a threat once the first white petals show.

How cold each stage tolerates

Cold tolerance in a strawberry tracks how exposed the tissue is and how much water it holds. We do not cite kill temperatures by the degree, because the published numbers shift with variety and with how fast the night cools.

• Open blossoms. These are the most tender stage. Ice forms in the yellow center near freezing and ruptures the cells that would become the berry.
• Unopened buds. Closed petals and the surrounding leaves shield the center, so a bud survives a few degrees colder than an open flower. A bud that has swelled and shows white loses most of that margin.
• Leaves. Mature leaves handle a light frost. A burned leaf costs the plant some growth, and the plant replaces it.
• Dormant crowns. Fall cooling makes the crown store sugars and shed water, which lowers the temperature at which its cells freeze. That hardiness fades as growth starts in spring, and our guide to strawberry winter survival covers that season.

Why blossoms freeze first

On a clear, still night the ground and everything on it radiate heat to the sky. A strawberry flower has almost no mass to hold heat, so it cools faster than the air around it. The chilled layer near the soil weighs more than the warmer air above, so it sinks into the bottom few inches and slides toward the lowest ground. Strawberries grow inside that bottom layer.

A forecast low describes air well above the ground across a wide area. Your blossoms sit below that air, shaped by your own slope and walls. Frost can coat the petals on a night the forecast held above freezing. Our guide to frost temperature for plants walks through that gap.

How cold your bed gets

In our own garden the station runs 7°F colder than the forecast low. The published last frost date for our zone 7a garden is April 28. Our last recorded spring frost came on April 30, and our learned offset moves the effective last frost date to May 20. We transplanted strawberry seedlings into raised bed 4 on May 10, ten days inside our own risk window. No frost came after April 30, and we got away with it.

Suppose your forecast reads 36°F on a night when your plants are in full bloom. A yard that runs as cold as ours would see 29°F, and the open flowers would freeze on a night the forecast called safe.

For every garden, Siltwell compares your threshold with the adjusted low for each of the coming two days. When either low reaches it, a frost alert goes out. The check runs at 5 p.m. local time, which leaves daylight to cover the bed. The default threshold is 0 °C, which is 32°F. The garden owner can set it anywhere from −20 to 20 °C, so during bloom you can raise it a few degrees and hear about a marginal night sooner.

The offset decides how far the forecast gets adjusted. Without a connected station you enter it yourself under Settings, Garden, Edit garden, Microclimate offset. With a connected station, Siltwell learns it from your station’s outdoor air temperature after about 14 days of overlapping station and forecast readings. The microclimate checker compares nearby home stations with the forecast. It gives an area reading, which can miss a cold pocket in your own yard.

What to do on a frost night

Cover the bed before sunset once the alert or forecast puts the low near your threshold. Frost cloth, an old sheet, or a row cover all work. Let the cover reach the ground on every side, because the heat it holds rises from the soil. Water a dry bed earlier in the day, since moist soil stores more heat and releases it through the night. Our guide on what to cover plants with for frost compares materials.

A threshold and a forecast can’t tell you how cold a single flower got. A blossom radiating to a clear sky can sit below an air reading taken a few feet away. We do not know how far below the air your blossoms run on a given night, since wind, cloud and mulch all move it.

The morning after, pull the cover once the air is above freezing so bees can reach the flowers, because a covered blossom goes unpollinated. Then cut a few open blossoms across the middle. A black center means that flower froze and will make no berry, and a yellow center means it came through. The plant keeps flowering, so later blossoms can still give you a crop.