A Rare Treasure in Nature: Discover Frost Flowers

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As the days grow cooler, one of my favorite activities on early morning walks in the late fall is to search for frost flowers. My first discovery of frost flowers was on one of my earliest trips to Kowalski Mountain when Philip and I were preparing for archery season. At first glance, frost flowers might look like a piece of plastic on the ground. They might also be confused by fluffy seed pods from flowering plants. However, this fascinating phenomenon is not actually real flowers at all, but beautiful ribbons of ice crystals. These tips can help you discover frost flowers if you are lucky enough to explore where they bloom.

What are Frost Flowers?

Frost flowers are also known as ice flowers, ice filaments, ice ribbons, ice fringes, or rabbit ice. These delicate structures of ice are only “blooming” during specific weather conditions. Frost flowers form after the air temperatures drop below freezing but the ground temperature remains warmer. The best time to start looking is after the first hard freeze of the season when the colder temperatures have not yet cooled the ground. In most places, these conditions are likely common in the late autumn and early winter. However frost flowers have been found in the spring, when these conditions are present.

Frost flowers form along the plant stems of certain native plants. While the plants appear to be dead, the root system of the plant remains active. When the ground is still warm, plant sap travels up the stems of certain herbaceous plants. After a hard freeze, the traveling plant sap creates small slits in the lower stems. Then the plant sap is forced through these fissures it begins to create ice formations. Each frost flower is uniquely formed based on the slit of the plant’s stem and through ice segregation which continues to freeze the ribbons of sap into a unique layer of ice. Frost flowers can look like cotton candy or spun glass.

What Plant Species Grow Frost Flowers?

According to James Richard Carter who published a very comprehensive article on frost flowers in American Scientist, not all plants produce frost flowers. He has verified more than 40 species of plants that form frost flowers in the right conditions. He actually studied frost flowers by “growing” them at home. By planting a garden of the specific plant species he discovered the delicate frost flowers “growing” and he was able to study their formation process.

In the state of Kentucky, frost flowers can be found on three native plants. The two most common are white crownbeard, also known by its common names as frostweed or Indian tobacco (Verbesina virginica), and common dittany (Cunila origanoides). Additionally, marsh fleabane (Pluchea camphorata) can produce frost flowers in wet areas.

In other states yellow ironweed (Verbesina alternifolia) and longbranch frostweed (Helianthemum canadense),  as well as stinkweed (Pluchea camphorata). Frost flowers have even been observed in states as far south as Florida! Tropical sage (Salvia coccinea), Wingstem (Verbesina alternifolia), camphorweeds (Pluchea camphorata), yellow crownbeard (Verbesina helianthoides) and ironweed (Vernonia novaboracensis) are all plants known to “grow” frost flowers.

Where to Find?

Frost flowers can only be spotted when conditions are optimal. The air temperature needs to be below freezing, while the ground temperature is still warm enough for any moisture to remain liquid. On a frosty morning take a walk in the woods where the ground is still moist. The best place to look is in shaded areas that are not mowed, or not mowed frequently. Frost flowers are often found along the stems of the tall weeds that they bloom on. The “flower petals” will look like puffs of cotton candy around the stems. It’s best to look early in the day or in areas that don’t get much sunlight. As soon as the sun rises and the rays of sunlight fall on the frost flowers they melt and are gone! 

Frost flowers are interesting to touch. You will be surprised that they are not as delicate to touch as you might think. If hiking with young nature explorers, allow children to touch frost flowers limitedly. While I encourage allowing them to explore and feel this incredible phenomenon, limit the number of frost flowers that they “pick” to allow other nature explorers the privilege of discovering them as well. 

When’s the Best Time to Discover Frost Flowers? 

The best time of year to look for frost flowers is when temperatures drop below freezing, but the ground is not yet frozen. Not all plants produce frost flowers at the same time. The sap is drawn up the stem of the plants by the capillary action that draws moisture from the root systems into the stems of the plants. As long as sap continues to flow, air temperatures are below freezing, and the plants are shaded from the sun, frost flowers will continue to bloom. We have found frost flowers from November into January. The best time to go on a hike is a cold morning before the sun rises high enough to melt the frost flowers. Observe the plants’ stems looking for the fluffy-looking flowers of ice.