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Why does fleece keep plants warm, when plants do not give out Body heat in the first place?

ObsessedPlantswomanObsessedPlantswoman Posts: 69
in Problem solving
That’s it really. Have never understood wrapping up plants as if they are people. We wear clothes because they stop our body heat from leaving, but plants don’t have any heat generation, so how can covering them up keep them warm? Where does the ‘warm’ come from on a winters day.

Eg if it’s 5 degrees one day, and you touch a fleeced plant, that plant does not feel hotter than 5 degrees!! Can anyone explain?


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  • Pete.8Pete.8 Posts: 11,340
    The warmth is in the soil and the fleece holds that warmth around the plant.
    It also buffers icy winds to prevent freezing - up to a point

    Billericay - Essex

    Knowledge is knowing that a tomato is a fruit.
    Wisdom is not putting it in a fruit salad.
  • Allotment BoyAllotment Boy Posts: 6,774
    Exactly as @Pete.8 says. Dark surfaces absorb heat during the day, and radiate it back at night, even in winter.  It may only make 1 or 2 degrees difference but it can be enough. 
    AB Still learning

  • ObsessedPlantswomanObsessedPlantswoman Posts: 69
    Sounds like the fleece should be black then, to absorb and radiate the heat into the plant..but fleece is usually white.
  • DovefromaboveDovefromabove Posts: 88,147
    edited June 2022
    As well as the explanations given above, it also forms a barrier and disrupts the flow of cold air running down a slope which is particularly useful in areas which form a 'frost pocket'.  Every little helps  ;)

    Gardening in Central Norfolk on improved gritty moraine over chalk ... free-draining.





  • AnniDAnniD Posts: 12,585
    An old thread with some possible answers. 
    https://forum.gardenersworld.com/discussion/1008648/is-there-any-good-reason-why-garden-fleece-is-white
  • LynLyn Posts: 23,190
    Those jackets they sell come in dark green. 
    Gardening on the wild, windy west side of Dartmoor. 

  • KT53KT53 Posts: 9,016
    Loft insulation, or any other form of insulation, doesn't give out heat either. The idea is to reduce heat loss in the air around the plant, and reduce the amount of cold air which gets in.
  • ShepherdsBarnShepherdsBarn Posts: 401
    And 'real' fleece (i.e. sheep fleece) also holds water, so helps to keep the moisture in the ground. I always line trenches and pots etc with fleece ... it's natural and supports sheep farmers. 🙂
  • ObsessedPlantswomanObsessedPlantswoman Posts: 69
    Cold air doesn’t go in, it’s the heat that’s moved away! Loft insulation stops heat from moving from below the loft to above into the loft. For fleece to work the same way, there has to be a heat source. If it is the ground, it wouldn’t take long for the ground to Eventually lose All its heat so the ground and the plant and the outside are all at thermal equilibrium...cold! 

    The benefit of fleece Must be minimal..will have a google for research!
  • SkandiSkandi Posts: 1,723
    happy_18mDZwQC2R said:
     If it is the ground, it wouldn’t take long for the ground to Eventually lose All its heat so the ground and the plant and the outside are all at thermal equilibrium...cold! 

    The ground will loose all heat when the radioactivity in the earth stops, the sun stops shining and the moon leaves orbit. But by then it will have gotten very hot on earth indeed.
    It takes the soil several months to warm up and several months to cool down again, soil is rarely as cold as the air even in mid winter. The only exception would be after a long cold spell when the ground is frozen solid and the air has started to heat.

    Maybe the biggest benefit of fleece is breaking the wind, it's not cold per say that does the damage to many plants but the drying effect of the wind on frozen tissue.
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