Hoar Frost - You Ask We Answer

Crystallised Eryngium - 7th December 2008, in my garden

In my Comments on Monday Gail asked:

Is this the famous English hoarfrost we have all read about! PS Our high school song spoke of the hoary walls and we all laughed in teenage ignorance!

I was just going to give a quick answer in my comments, but what better topic is there for You Ask We Answer than the great British weather? So the YAWA staff here sprang into action immediately to find out.

The word hoar comes from the Middle English hor, which in turn comes from the Old English har. It's related to Old High German, which makes me wonder if there's a connection to the German word haar (hair), which we're singing about in Silent Night at choir at the moment. Hoar itself has two meanings: the first is ancient, such as a hoary beard, which means one whitened with age, just like NAH's! The second is white, thus giving us the descriptive white frost, sometimes used instead of hoar.

The BBC Weather Pages says hoar frost forms when the air cools so that water condenses out of the air onto garden surfaces such as grass, plants, or as my photos showed on Monday, sheds and fences. This is quite different to frozen dew which looks like frozen water droplets, whereas hoar frost has a delicate, ice crystal structure. According to WeatherOnline, the objects the water condenses onto must also be below freezing and the resultant hoar frost looks like needles, feathers and spines. It also suggests that the air must be supersaturated with water i.e. above 100% humidity for this effect to take place. Hoar frost shouldn't be confused with rime, which forms from freezing fog, or glaze which forms as a continuous sheet of ice. Unlike hoar frost, both aren't formed from individual frozen droplets.

The BBC website gives two further definitions: Air frost is when the air temperature reaches zero degrees centigrade (32 degrees Fahrenheit), though the ground can sometimes stay above freezing. This often happens in early autumn, as the soil still retains some of its summer heat. Ground frost is when the ground's surface temperature reaches zero. This can happen even though the air temperature may remain above, at say 3 or 4 degrees centigrade.

On very special days hoar frost gives us that 'winter wonderland' effect, which when combined with sunshine can be magical - as shown in this magnificent photograph. There's also an apple called Hoary Morning, originating from Somerset in 1819. Its skin has a deep bloom like hoar frost, hence the name.

So Gail, I suppose the short answer to your question is yes, my photos did show hoar frost, but I hope you've enjoyed my longer explanation and a further picture from Sunday. Now, how did your hoary high school song go? ;)


  1. Hello VP and thank you for today's YAWA lesson! You are a good tutor no no wrong you are an excellent tutor...:-)

    LOL Tyra

    New Post from Tyra - Leufstabruk

  2. We have had several hoar frosts already this year in Dorset. We have been having some mild winters with hardly any frost at all but last year we had a few frosts and this year is looking very cold. It was -5C this morning and out of the sun is still below freezing here.

    Lets hope it will kill a lot of the newer bugs we have been getting - now if it killed the lily beetle I would be very happy, worth getting cold for!

    Best wishes Sylvia

  3. I like the textures in this photo very much. Yesterday's photo was pretty neat too. I'm glad you posted about being undecided. As a new writer myself, it was very informative reading everyones responses. Good luck with your decision.

  4. do we have to pay $49.99 to read this informative post?

  5. Ahhh thank you! I love etymology! Here so far we've only had ground frost so my tall, dark burgundy chrysanthemums are still blooming!!! LAst year they lasted till a few days before Xmas! They're not really an outside flower, bought in a pot for display indoors only. This means they are partial to bad rusts. Every year I spray them but every year I end up taking off lots of affected leaves, leaving just a few good ones. It is tiresome. But this time of year I see them, the only flowers around abouts, and it is so worth the effort!!!

  6. VP,

    Thank you for the answer to my question! Hoar frost is beautiful and I don't believe we have it very often here...or I am not quick enough to notice it. Now I shall be on the lookout! More reasons to have that new camera!

    To answer your question...only one line comes to mind and a search of my yearbooks (yes I still have them!) reveals nothing! I will continue to search for it! But it is something like 'The hoary walls of Normandy...' We had many old brick buildings!

    The love link is much appreciated!


  7. I'll never get to see hoar frost here on my corner of Katy so I'm very much enjoying your pictures, and the explanation of this meteorological phenomenon. Thanks, VP!

  8. That was very interesting - next time it's frosty I'm going to pop outside and see if it's hoar frost or frozen dew. A more intellectual reason than usual for getting the camera out (lol)

  9. Very informative! We have hoar frosts here occasionally (http://nancybond.wordpress.com/2008/01/31/frosty-mist/) and they're so beautiful, especially with the sun on them. Thanks for the info!

  10. Very cool...I had never hear of hoar frost before. Always come away from here just little smarter!!!

  11. I enjoyed it very much! That tree in the photograph is magnificent. It looks like snow.

  12. What a great post! We woke to a hoary winter wonderland this morning :) I threw on some pants, a hat, and a jacket over my pajama top and got some pictures while the light was good. I wonder what the neighbors think sometimes...


  13. I just loved learning more about this!
    I will look for this in the High Sierras.
    I enjoyed the word origins you provided, too.
    Best regards,

  14. Thanks for the info! At least it explains the "hoar" part of my favorite common plant name, Hoary Puccoon. Now if I can just find out what a "puccon" is...

  15. Hi everyone - glad you enjoyed the explanation, especially Gail who asked the question in the first place. I've several of these in mind under the You Ask We Answer umbrella ;)

    Like Sylvia I'm hoping our hard frost will kill off all the bugs, particularly the Horse chestnut leaf miner I wrote about earlier in the year.

    Emma - what do you think? Did you pay to read it? Did Tyra, Inadvertant Farmer or anyone else for that matter? ;)

    Lily Hydrangea - welcome! Thnaks for stopping by :)

    Cindy - I think you don't get them because the States winter air is drier than ours? I've added a little note about it ready for GBBD on Monday.

    Helena, Philip and MMD - I love word origins too. It was good to go and do a little research and I've been waiting for an excuse to write about the Hoary Morning apple as it's one of my favourite names.

    Nancy - your frosty mist was lovely :)

    EG and Blossom - it's always great to have an excuse to go out with the camera and who cares what the neighbours think? :)

  16. Cindy - ah silly me, you're probably too warm a climate down your way to get them aren't you? I've cancelled my little bit for tomorrow's GBBD.

    Good to see you here :)

  17. Thanks for the info on hoar frost. Aren't Eryngium grand? Some snow-capped ones in November at my friend's house are here.
    ~ Monica

  18. Garden Faerie - Bananas! they're fantastic!


Post a Comment

I love hearing from you and welcome thoughtful conversations :)

Comments aiming to link back and give credence to commercial websites will be composted!

Your essential reads

Garden Bloggers' Blooms Day: 'Just Add Cream'

Wildflower Wednesday: Alpengarten

Salad Days: Mastering Lettuce

Dessert Apple Jelly: Seasonal Recipe

Garden Bloggers' Muse Day: The Best of Summer

Jack Go To Bed At Noon

Weekend Wandering: To the Sunflowers!

June Drop

Wildflower Wednesday: A New Year Plant Hunt

Weekend Wandering: A new sculpture trail