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First Frost Flowers of the Winter

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We got our first frost flowers of the year Thursday, 12/5.

A stick growing frost that looks like short pure-white hair. On a bed of brown leaves.
Stick 1 has an elegant swirl frost off the end

Please note that the general frost flower commentary below is taken from this post from a couple years ago. All the photos are new.

Frost flowers (hair ice) form when there are sodden sticks that dip below freezing overnight. Around here, the sweet spot is ~28-31 F. It needs to be cold enough to produce frost, but not so cold as to freeze the stick solid.

A stick growing frost that looks like short pure-white hair. On a bed of moss and leaves.

The ice forms on the surface of the stick, and is extruded as it freezes to form “hair” which can take beautiful forms that look like silvery locks or silvery flowers.

Close-up of frost. You can see each strand.
Closeup of stick 2

There is a fungal association with Exidiopsis effusa. Around here, there is also a clear preference for alder twigs and branches. I’m not sure whether that’s what the fungus prefers, or whether the wood somehow favors frost flower formation.

Closeup of small twig that has a burst of frost growing like a flower out the end
Tiny burst frost “flower” growing out the end of a small stick. It is uncommon for such small sticks to have such a nice formation; it is likely because the bark prevented any from extruding out the sides.

Frost flower and hair ice are two terms used semi-interchangeably. As far as I can tell, the distinction is mostly based on the type of formation. If it’s a burst formation (e.g. from the end of a stick), it’s a frost flower. If it looks like hair growing out of the middle of a stick, it’s hair ice. Even though most of what we get is probably more hair ice than frost flowers, I like the latter term better 🙂

Frost growing out the end of the first stick. Some of it has curled into a graceful wave formation, clearly visible against brown leaves
Stick 1 closeup of “wave” growing from the broken end of the stick.

Frost flowers and hair ice are relatively rare worldwide. They require specific conditions to “grow”. In climates with cold winters, you might be lucky enough to see a few in the autumns. 

Extreme closeup of wave formation formed of strands of frost.
Stick 1 extreme closeup

Here in the Puget Sound area, the winters are mild and tend to only dip below freezing occasionally. We also have an abundance of alders. That gives us the ideal conditions for hair ice and frost flowers.

A mossy stick with fine hair-like strands of frost bursting out through splits in the bark.
The moss is growing on the bark of this stick. The hair ice can only grow out where the bark is split.

To see them, go out on a cold morning and check any local alder groves. They tend to be more common at the edges of alder groves, where the sticks are a bit more exposed… but that depends on the temperature range. On a very cold morning (25-28F) there may be such formations deeper in the woods.

A stick growing luxuriant curls of hair ice out one side. They look like pure-white locks of hair.

They are most common on mid-sized twigs and branches (~1/2-2″ diameter), but occasionally they grow on larger or smaller branches.