flowers of ice

An early iris from my garden

One of my favorite things to do is putter in my garden. By this time of year, I really miss working outside. Plenty of kale, collards, broccoli and mustard greens are all that remain from last year's plantings. A few green chives are poking out of the ground along with the first of my bulbs. Mostly, the garden sits dormant until light levels and temperatures increase.

I've gone through the thought exercise of planning my summer garden, including making sketches of where everything will go. Seeds are ordered. In a few weeks I'll start some seeds in the house. Normally winters where I live are mild, so in theory I could be doing some digging, but below freezing temperatures and frost has kept me indoors.

In my recent reading I stumbled across 'frost flowers' – blooms for this time of year. They appear almost magical and present some real dangers. Three different, but similar phenomena are often labeled 'frost flowers.'

Frost flowers on glass

This is the only type of frost flower I've ever seen. Years ago, I lived in northern Alberta where winters were solidly cold. Going anywhere in winter took preparation including scraping frost from the windshield and warming the car. Once I was out on the road, frost would 'grow' up the inside of my windshield in fern-like formations. I'd often have to scrape it away just to see the road in front of me.

These two-dimensional growing crystals of ice can form on glass, or any non-insulated surface, where the outside is much colder than the inside. As heat is lost from the inside surface, the moist inside air freezes against the glass. The resulting shapes are determined by imperfections on the glass such as scratches or dust, making each one unique. These blooms always look more like ferns than flowers to me.

Frost flower growing from plant stems

These flowers form like ribbons (also called ice ribbons) from plant stems when the air temperature is below freezing but water in the soil has not yet frozen. Sap in the plant freezes, and since water (a major component of sap) expands when it freezes the plant's stem splits to make enough room. Water from the soil is drawn up into the stem where it also freezes, pushing a ribbon of ice out of the plant. As the ice is forced through the split stem, it undulates and curls into a shape reminiscent of a flower. These delicate flowers are fugitive, as soon as sunlight hits them they sublimate away.

Sea-ice frost flowers

In polar regions fields of frost flowers bloom when conditions are right. These flowers may form on a calm, cold night over newly formed ice (nilas). The air needs to be much colder than the water below as this temperature difference is key to ice flowers growth. Like the frost flowers formed on plants, when sunlight hits their petals, the water quickly sublimates and the flower vanish.

If you are ever trekking across sea-ice and see a field of frost flowers, find a way around. According to On Sea Ice by W.F. Weeks, the flowers hide the dark colour of the thin ice beneath – ice too thin to support a person's weight.