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Days Until First Frost

Last Frost Date for the North Shore

by Elizabeth Spence

WHEN IS THE LAST FROST DATE ON THE NORTH SHORE?

The only answer to this question is: it depends.

We need to know the last frost date so that we can sow seeds and transplant into the garden what we have started inside, knowing that they will not be killed by the frost.

Frost dates are never cast in stone because there are so many variables.

The first important variable is the zone we are in. We are generally in zone 5 here on the North Shore.

The second variable concerns the microclimates in your area. What this means is that the frost dates in your own garden, let alone two or three miles away on the North Shore or even down the road can be different. (See our article on Zoning).

The traditional wisdom in this area is that you should wait until the first full moon in June before planting out.  That’s June 21st this year (2024).  Sometimes you hear that you can plant at the full moon after June 10th.  

June’s full moon is called the strawberry moon, since it was a sign to North-Eastern native Americans to harvest ripening strawberries. 

The Strawberry Moon in June

We are given information on frost dates from all kinds of official and semi-official sources.

The Farmer’s Almanac 

The Almanac is a wonderful resource for all sorts of gardening information. 

However, they are the first to admit that identifying the last frost date for planting outside is not an exact science. They say that they are giving the average of the light freeze days, and the frost dates are a 33% probability.

Furthermore, their information is calculated based on data from NOAA National Centers for Environmental Information, which only goes up to 2021.

Enter “Tatamagouche” on the Almanac’s “Frost Date Page” and you get this:

Nearest Climate Station

Altitude

Last Spring Frost

First Fall Frost

Growing Season

MIDDLEBORO, NS

98′

Jun 8

Sep 26

109 days

Middleboro is about 20 miles away from Tatamagouche, it is inland, and has an elevation of 98′, where Tatamagouche is on the coast and has an elevation of between 0’ and 40’.  The last spring frost is given as June 8th.   Is this useful information for us?  It’s earlier than the received wisdom of June 21st.

If we enter “Pugwash” we get

Nearest Climate Station

Altitude

Last Spring Frost

First Fall Frost

Growing Season

PUGWASH, NS

13′

May 17

Oct 10

145 days

Does anyone in or near Pugwash plant out as early as May 17? Let us know!

Plantmaps.com gives us this map. 

This is absolutely useless because the zoning is completely wrong. Nova Scotia is zone 5 or 6 depending where you are, not zones 7-12!  It shows you have to look very carefully at these sorts of maps to make sure that even the basic information is correct. 

Even their Plant Hardiness Zone map shows us as zone 6a which doesn’t agree with the Government of Canada map which shows us as Zone 5a.

This isn’t worth much either, because here, the last frost date in Nova Scotia is given as “before April 29th”!!  We all know that can’t be right, for gardeners anyway.

Then we have Vesey’s garden mail order house providing us with last frost data: 

This is taken directly from government sources, and doesn’t apply to us at all. None of these places is anywhere near us.

So what do you do?

The simplest thing is to accept that the full moon on June 21st is the key date and wait until then.

Or – you can gather information from other sources.

Test Your Soil Temperature

There are minimum soil temperatures essential for seed to germinate and for transplants to thrive. It varies according to what you are growing.

Soil thermometers are readily available – or you could use the method given below in “Folk Wisdom.”

It’s the seeds and the plants themselves that determine the temperature they need, and they know best. Here’s a soil temperature planting chart from the Farmers’ Almanac:

Ask Your Neighbours

When do they sow seed or plant out?  What strategies do they use to protect their babies from the frost?

Jennifer is the expert here.  She has kept a diary of the last frost days in Tatamagouche for four years.  They are:

2020: June 14th;   2021: June 13th2022: frosty June 8th, 2023: hard frost May 23rd.

  • She advises watching the weather news for frost advisories and warnings and then she takes note if they are correct. There are “light frosts” and “killing frosts.”
  • Then she checks for any frost damage to her plants.
  • Whether there is or not often depends on the various microclimates in her garden which she has come to recognize over the years.  Her overall microclimate is a forest glade.
  • It also depends on what the plants are. She is very careful about this. Some plants are extremely tender – basil, asparagus and cucumbers for instance will probably wilt if you even mention the word “frost,” while snapdragons, onions and cabbages are a bit more tolerant.  
  • The advice here is: know your plant!  How hardy is it?
Asparagus
Cucumber
Cabbage
Snapdragons
  • It also depends on where you are sowing or planting. Jennifer uses raised beds in which the soil temperature is naturally higher than the native soil
  • She also consistently uses row cover as extra protection. (See our article on Row Covers.)
  • This is being written on May 11th, and Jennifer is already confidently sowing her carrot seeds. She will have an early crop.
A Raised Bed
Floating Row Cover Over Raised Bed

Sue Danko, a former market gardener, has this to say about transplanting:

“My personal frost-free date is the third week of June, because I have experienced a severe frost (-5) on June 23 right here in Tatamagouche/Balfron.

I usually transplant tomatoes, peppers and squash into the garden from mid-June through the end of June.  It never happens all at once.

Tomato Transplant
Pepper Transplants
Squash Transplant

People could consider June 8 as the date to start planning the transplanting, but they have to do some thinking and observation. . . .

My formula for predicting if there will be a frost is:

 6 pm. 10 degrees or lower.  Dead calm.

Clear sky with no forecast of clouding over.  

There will be a frost.  

Hold off planting or be prepared to cover your crops.  You have to think about frost right through until the end of June. “

Thanks Sue!

Folk Wisdom

There is a vast amount of folk wisdom about when to sow seed or transplant outside.  Not planting until the first full moon in June is one example.  But there are lots of others.

  • Plant carrots when the daffodils bloom
  • Plant beans when the apple trees are blooming
  • Plant the peas when the peepers peep
  • Plant squash when the lilacs are in full bloom
  • Plant cucumbers when the lilacs have faded
  • Transplant tomatoes when the lily of the valley is in full bloom
  • Test the temperature of the soil by sitting bare-bottom on it. (Or you could use a soil thermometer).

Reciting an old Scottish poem is supposed help as well!  Here’s the first verse:

The Consecration of the Seed (An Croisrigeadh Sioil)

I will go out to sow the seed,

In the name of Him who gave it growth;

I will place my front in the wind,

And throw a gracious handful on high;

Should a grain fall on a bare rock,

It shall have no soil in which to grow;

As much as falls unto the earth,

The dew will make it to be full. . . .

 

Most of this is based on watching what is going on around you; keeping an eye on what nature is doing.  That will be specific to your area, and fairly reliable on the whole.  There will always be a rogue frost, of course, but you prepare for that.

Observing nature to tell you what to do is all part of what today is called “phenology.”

Phenology

Robert Marsham (1708 – 1797) from Norfolk in England is considered to be the first scientific phenologist, although the term “phenology” wasn’t coined until the 1840s. 

The word derives from the Greek meaning “appearance” and “knowledge.”  That is to say, the knowledge you gather from observing the first appearances of natural events in spring.

For 62 years Marsham noted the natural events of plants and animals: when certain trees started forming buds, when certain plants were starting to appear or open out or go to seed, and so on.

He created a natural botanical calendar for his area by compiling records of his observations and called it Indications of Spring

In Canada, the PlantWatch site  is doing a similar thing.  

They are asking people all over the country to note when specific plants come into flower, etc. and report the information.  This is then used for identifying ecological and environmental changes in the country.

It would be very useful for determining planting times as well. And wouldn’t it be wonderful if schools were involved in this?

During Jennifer’s studies into phenology, she came to know of Greg Auton in Halifax.  He is intensively studying the dandelion and how it can be used as an indicator for sowing and planting.

Here is a chart he has made up which shows what to plant when according to the dandelion, although he cautions too that this can only be a general guide.  The green represents when the plant is leafing out, the yellow when it’s in flower, and the white when it has gone to seed

The nice thing about all this is that you are relying on nature around you and on your own two eyes.  Nature doesn’t listen to official statistics, so you’re not going to be led very far astray.  After all, people have been doing it for thousands of years.

Planting by the Moon

We know that the moon influences the tides on earth, but the question is: does it affect the movement of moisture in plants, for instance, and what effect would it have if it did? 

(As an aside, my mother was a midwife, and she knew she would be busy at the time of the full moon).

We have several extremely knowledgeable and experienced biodynamic gardeners in the area.  Biodynamic gardening is based on observing and working with the natural, astronomical and astrological rhythms of the world. 

Today it is primarily based on the work of Maria Thun called the Biodynamic Almanac. 

In this system, plants are divided into four groups: root, flower, fruit and leaf.  Here is a calendar from the 2022 calendar. 

I have done a brief survey of the scientific literature on the subject.  There doesn’t seem to be much, and the results appear contradictory.  If anyone knows of any good studies, please let us know.

If you wish to learn more about biodynamic gardening, contact us, and we will put you in touch with the experts.

Conclusions

Like almost every question to do with gardening, the one about the last frost date is a minefield.

The best we can do is

  • Know our zone – it’s zone 5 here on the North Shore
  • Get to know the microclimates in our yard, or create them
  • Ask all the gardeners you know what they do.
  • Check the soil temperature
  • Keep an eye on the weather forecasts
  • Have lots of row cover on hand
  • Observe what nature all around is telling us
  • Study the moon and the stars
  • Keep our fingers crossed and have a stiff drink!

Copyright © 2024 Elizabeth Spence.

4 Responses

    1. Hello Lynn,
      Thank you. We hope it will be useful for everyone.

  1. My neighbour (a farmer and fisherman) in Wallace always said that the temperature of the water in the bay was also a good indicator for predicting frost (in combination with the Full Moon).

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