Leave a bouquet on a Minnesota porch on a January night and by morning it shatters like glass. That is the whole idea behind “Frozen Flowers”, part 16 of the Minnesota Cold video series, filmed in Minneapolis and published on 17 January 2016.
The flowers were donated by Chicago-Lake Floral, a florist in Minneapolis. After a night outdoors, petals and leaves that bent easily the day before crack and crumble in the presenter’s hands. Watch it below, then read why it happens.
The Minnesota Cold video series
Minnesota Cold is a YouTube series of short cold-weather experiments filmed outdoors in Minnesota. Each episode takes something ordinary, such as soap bubbles, boiling water or, here, a bunch of flowers, and shows what extreme cold does to it. The frozen-flower episode is one of the simplest: it needs nothing more than a bouquet and a cold night.
Why frozen flowers shatter
Flowers are mostly water. Petals, leaves and stems are built from cells full of watery sap, kept firm by internal pressure. That is what makes a fresh flower soft and springy.
When the temperature drops far enough, that water turns to ice. According to South Dakota State University Extension, water inside plant cells can solidify, expand and rupture the cells. Frozen solid, the tissue loses all its flexibility. Bend it and it has nowhere to go, so it snaps, just as an ice cube would.
Thin, water-rich parts freeze first and break most dramatically, which is why petals crumble while thicker stems may only crack. Once thawed, the ruptured cells cannot recover, and the flowers turn limp and dark.
Frost, freeze and hard freeze: the numbers
Gardeners use a few simple thresholds, as set out by SDSU Extension:
- Frost: forms when air is near freezing (roughly 33 to 36°F) and plant or ground surfaces reach 32°F (0°C) or lower, so moisture turns to ice crystals.
- Freeze: air temperature drops to 32°F or below.
- Hard or “killing” freeze: 28°F (−2°C) or lower, cold enough to kill most plants that are not dormant.
Duration matters as much as the reading on the thermometer. A few minutes of frost may do little harm, while several hours can cause serious injury. A cut bouquet left out all night in a Minnesota winter is far past every one of these limits.
Winter-hardy perennials and dormant shrubs survive the same nights because they prepare in autumn, shedding water and adapting their cells to the cold. A greenhouse-grown cut flower has no such protection.
How cold Minnesota gets in winter
Minnesota winters are among the harshest in the lower 48 states. In Minneapolis–Saint Paul, the January average high is 23.6°F (−4.7°C) and the average low 8.8°F (−12.9°C), with a record low of −41°F. Temperatures as low as −60°F (−51°C) have been recorded in the state. International Falls, near the Canadian border, has the coldest average annual temperature of any first-order National Weather Service station in the contiguous United States, at 37.4°F (3°C), which earned it the nickname “Icebox of the Nation”.
To try it yourself, pick a still night well below 0°F, set the flowers on a tray outdoors and handle them with gloves in the morning.
For another delicate cold-weather experiment, watch ZALUSKArt’s frozen soap bubbles, or read the explanation of boiling water and a visible winter plume.
Related reading
- ZALUSKArt’s Warsaw Bubble Photographs: The Stages Before the Surface Freezes
- Coloured Ice Orbs: A Winter Craft with Water and Balloons
- Frozen Bubbles at Mount Washington Observatory
- Soap Bubbles in a Thompson, Manitoba Winter
- Hot Water in Extreme Cold: What the Pale Cloud Shows
- Chris Ratzlaff’s Frozen Soap Bubbles in Calgary
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