Micro-season: “The Frost Stops the Rice Grows”

We have entered the micro-season of “The Frost Stops the Rice Grows”, which is the second micro-season of the mini-season of Grain Rain. 

Each mini-season contains three micro-seasons. The micro-seasons contained within Grain Rain are:

These seasons were established in 1685 by Japanese astronomer Shibuka Shunkai and are specific to Japan. However, just because the calendar focuses on Japan doesn’t mean it isn’t applicable to others.  No matter where you live you can use these seasons as a starting point for your personal exploration of the world around you. 

This micro-season tells us that it is time to turn our attention to the gardens. It is the time when the farmers begin to move the little seedlings from the greenhouse out into the fresh air. But as this micro-season indicates, we should be wary of winter’s last gasp.

If we bring our plants out too soon, that last frost might ruin our dreams of a bountiful harvest. 

What is Frost?

Frost occurs in two stages.  First, the temperatures on outside surfaces must drop below the dew point.  This allows water vapor to turn into liquid.  Then, as the temperature continues to drop, the water will freeze into ice crystals, These ice crystals are what we call frost.(1) 

Frost is then separated into four categories:

  • Radiation frost: Radiation frost forms on the ground and or outside objects.  This type of frost looks like small ice crystals 
  • Advection frost: This frost forms on branches and poles and looks like very small ice spikes. This type of frost is created as the cold air blows over these surfaces. 
  • Window frost: This type of frost forms on windows. Window frost is a result of the colder outside air meeting the warmer, moister, air inside a house.  
  • Rime frost: Rime frost forms in wet and windy climates.  This type of frost often looks like solid ice.  If you have ever seen pictures of the ships traveling through the arctic covered in ice, this is an example of rime frost.(1)

Frost’s Impact on Plants

Planting any delicate crops prior to the last spring frost could result in the potential loss of the crop. When the temperature drops enough to create frost it has the potential to freeze the water that is found within the plant tissue.  This freezing will cause significant damage to the plant, and it may even kill the plant

Because of the potential damage that frost can cause to plants, farmers have established systems to identify the last frost dates for their region.  These “last frost dates” are calculated by looking at historical weather data in order to help predict future weather patterns.  It should be remembered that predictions can only provide estimates and should not be taken as definite dates.  In fact, The Farmers’ Almanac estimates that there is a 30% chance that the freeze dates will fall outside the predicted dates.   

The Last Spring Frost in Japan

In Japan, 85% of the farms produce rice crops.(3) So knowing when that last frost might come is important.  However, because of the range of climate found in Japan, the last frost can vary from March 10 in the southern city of Kagoshima, to April 21 in the northern city of Sapporo.(4)

When taking this into account we can see that this current micro-season seems to be more aligned with the northern regions of Japan than the southern.  This makes sense because the Tohoku region is the largest producer of rice in Japan.(5) Tohoku is the northern section of the main island and includes Aomori (Average last spring freeze – April 20) and Fukushima (Average last spring freeze-April 13)

Prefectures Of Japan: Photo Credit – WorldAtlas.com

If you are interested in finding the final spring frost dates of other global locations you can use the Global-Freeze Database created by Utah Climate Center at Utah State University.  This database has first and frost data for over 20,000 locations worldwide, plus 300 locations in Utah. 

The Last Spring Frost in Vermont

Vermont is a relatively small state in the northeastern United States. It is part of the New England region and borders Massachusetts on the south, New Hampshire on the east, Lake Champlain and New York on the west, and Canada on the north.  Vermont is also known as the Green Mountain State because the Green Mountains run from north to south in the western part of the state.  

Since I live in Vermont, I am very aware of the difference in weather from the northern border to the southern border.  This made me wonder what is the difference in the last spring frost across the state. I am especially curious about the difference between the southern towns and those on the northern border. To explore this idea further, I picked three towns to investigate using the Global-Freeze Database.

Brattleboro is a town located in the southern part of the state.  This town is located at an elevation of 633’ above sea level and the Connecticut River forms its eastern border.  

  • The average date of its last spring frost in Brattleboro is May 17.

Waitsfield is a town located in central Vermont.  It is located at an elevation of 800’ above sea level and in the Mad River Valley between the Green Mountain Range and the Northfield Mountains.

  • The average date of the last frost in Waitsfield is May 09.

Newport is a town located in northern Vermont. It is located at an elevation of 682’ above sea level.  It sits on the southern shore of Lake Memphremagog is about 7 miles to the Canadian border.  Newport is also about 170 miles from Brattleboro.

  • The average date of the last frost in Newport is May 17.

Looking at the data, it seems like the last frost date is pretty close between the northern parts and southern parts of Vermont.  I found this surprising. This also makes me wonder about the impact of altitude, waterways, and mountains on frost dates.

It should also be noted that all these last frost dates are not until early or mid-May. This means we have a couple weeks’ difference between the weather patterns in Vermont and those in Japan.

I guess it isn’t time to plant anything yet!

Haiku About This Season

The haiku to honor this micro-season comes from Kobayashi Issa, Matsuo Basho, and Yosa Buson.

Issa will start us off with a few haiku about spring frost. 

morning frost melts
in the floodtide...
Shinto shrine
down to two leaves
the lonely morning-glory...
spring frost

Next, we have a haiku from Basho about planting rice.

The first poetic venture 
I came across- 
The rice-planting songs 
Of the far north. 

I have seen several variations of this haiku by Basho.  This version comes from his journal, “The Narrow Road to the Deep North” translated by Nobuyuki Yuasa. 

Yosa Buson then gives us another snapshot of rice planting.

having caught a catfish
he goes back to rice planting
what a man

And for the final haiku, we return to Issa.

after seeing rice planting
in remote provinces...
the geese depart

I really like this haiku by Issa because it blends the seasonal activity of rice planting with the migration of geese. I think this is a great way to show the connection between human activities and the patterns of the natural world.


  1. “Frost”: National Geographic’s Resource Library
  2. “Frost Dates”: The Almanac
  3. Rice production in Japan”: Wikipedia
  4. “Rice Cropping?: Kid’s Web Japan/Explore Japan/History
  5. “Japan Freeze Dates”: Utah Climate Center
  6. “Vermont Freeze Dates”; Utah Climate Center
  7. Town Climate Data: BestPlaces.net

Issa’s haiku were retrieved from  David G. Lanoue’s site, Haiku of Kobayashi Issa, and World Kigo Database.  

Want to support our work? Visit the Naturalist Weekly bookstore and browse our curated lists of books of poetry and haiku. Or pick up a gift card that can be used throughout the store.   

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17 thoughts on “Micro-season: “The Frost Stops the Rice Grows”

Add yours

    1. Hi Tracy, it definitely feels like that sometimes. Especially when I wake up in the morning and it has snowed again! Winter is hanging on this year.

      1. It’s the opposite here, although we did get a bit of snow on Sunday night. Started out as rain and then became flakes. Our dry, thirsty soil welcomed it. Send any surplus snow from VT to CO! 🙂

  1. I grew up in Northfield, MA, just south of Brattleboro, and on the Connecticut River. My dad never planted until Memorial Day, as frost was frequent in early May. A well know Central Mass master gardener always advises, “The safest day to plant in Massachusetts in May 32.” 😉

  2. I agree. The last haiku form Issa is my favorite too. I stayed at a friend’s house in Japan that was surrounded like an island in a sea of rice fields. It was surprisingly warm and humid for May and the bullfrogs were so loud I thought I would never be able to fall asleep. It was such a great experience though! There is no greater honor than being allowed to stay at someone’s family home in Japan. I would choose to be treated like a family member a hundred times over than stay in a 5-star hotel as an outsider.

    1. Hi Melanie, That sounds like an amazing experience! I agree that it is so much better to be able to stay with locals when you travel anywhere, especially when you go out of the country. Our spring peepers just started singing. Nothing like a bullfrog, but a sign of spring.

  3. I’ve leaned much from this article. I especially enjoyed the information on the varieties of frost and I do in final frost dates. Thank you for the parting haiku, as well. Here’s to the end of freezing and the beginning of a fruitful season.

    1. Thank you for your comment and I am very glad that you found this useful!
      That last haiku by Issa is pretty awesome. I really enjoy Issa approach to observing the natural world. As for spring, I think we are almost there! Thanks again!

      1. You’re very welcome. Cheers to spring! We already have a processional of blooms here in VA. The pops of color keep on coming, though. I do so love spring’s surprises.

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