Frost Hardiness

This isn’t a simple, it’s hardy down to -10°C therefore…

Eucalyptus Hardiness and Frost tolerance is influenced by other factors:

  • the health of the tree when planted
  • soil condition
  • site location, exposure, shading, distance from the coast for some varieties

Interestingly it’s not the cold that will cause injury to the tree, assuming it is frost tolerant. It will be the lack of hydration if the frost continues for a long period. You can’t drink ice 😏
Hydration is the important factor !

Actually planting your Eucalyptus, whether from a plug or a poly pot may be better than leaving it above ground in its container, how does this work The ground is an insulating layer. Every heard of ground source heat pumps, or geothermal heating ?
Ahh, again it’s not a straight forward answer. It depends on how deep the frost penetrates. A blanketing of snow will also be beneficial as it will add an insulating layer.

So now we are both confused 🤔
Research on the internet is even more confusing with conflicting arguments. Authoritive studies and papers don’t offer much help either with their differing opinions.

Whats the solution and my recommendation ?

I have now planted Eucalyptus throughout the year, and by far the main consideration is hydration, followed by exposure to cold winds. I’m not particularly concerned about frost when planting assuming that the frost is not prolonged or severe, i.e. doesn’t penetrate too deeply.

A strategy for most growers will be to stagger their planting, i.e. perhaps 25% of your mini forest in January, 25% in February etc. If you can ensure hydration then planting throughout the year is fine. If you are a small grower, then the above is perhaps the easiest solution.

In an unpredictable and changeable climatic world, this staggering of planting Eucalyptus trees would seem to me to be the best way of ensuring success with you mini forest.

I planted the plugs and poly pot trees on a day where the night before the temperature in the poly tunnels got down to 2°C Perhaps a degree or so colder outside. Though there was no frost on the ground first thing.

I’ll keep a diary of the poly tunnel temperatures during the next four or so weeks while I try to discern factually whether planting Eucalyptus during mild frost periods is acceptable practice.

NOTE the temperatures below are Poly Tunnel temperatures

DateTemperature (Day)Temperature (Night)Weather GenerallyOther Comments
29/01/1924.72Trees planted, bight sunny day with squally showers of hail
30/01/1923.40Calm with reasonable snow overnight and frost
31/01/1931.4-1.7Early frost, rain and moderate wind
01/02/1914.8-1.8Reasonable frost, though didn’t penetrate the ground. A calm, dry and bright day.A very dry frost, though there is plenty of moist hydration in the ground. This is the most important thing. Evergreen trees need to drink when they are planted.
02/02/1930.1-3.5More server frost, some ground penetration. Generaly a calm, dry and bright day, though a short shower of heavy sleet midday.A very dry frost, certainly less surface moisture.
03/02/1924.8-1.3No frost this morning. Overcast and calm.
04/02/1915.13.5Bright calm day all day.
05/02/1933.12.1Heavy rain most of the day, at times torrential.
06/02/1918.31.8A fair day, some showers of rain. Generally mild.
07/02/1933.82.5Definitely a colder feel to the day, despite the slightly higher poly tunnel minimum.
Temperature chart Poly Tunnel Feb 19

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