Freeze and Thaw Cycles
Plants are not warm blooded and so the dangers from cold, freeze/ thaw cycles can have a devastating effect on their survival. Ice crystals pierce cell membranes with sometimes fatal consequences. A plants survival is dependent on its' ability to prevent ice formation in the roots and stems.
Winter hardy plants have an ability to produce minimally required amounts of anti-freeze within their tissues. As it freezes the plant begins to decrease its' water content and transform it into anti-freeze. It is still not clearly understood how it does this. Suffice to say that it requires a lot of energy from the plant to accomplish this.
Cold-hardiness is mostly genetically pre-determined. Over time and by saving seeds and adapting each generation to the local temperature fluctuations it is possible to have certain varieties become more tolerant to cold.
I have a bay laurel that should NOT have survived the cold of -17C a few years ago. I started it from a cutting many years ago and for the first 5 years or so of its' life here at Ironwood Farm I took extra care to wrap and cover it during the winter. It was only after 5 or so years that I risked leaving it to fend for itself. It survived even though it looked a mess. I had to severely prune out 3 feet of its' height and a lot of its' width. But wonder upon wonders there was new growth sprouting out from the bottom !!
Soils hold a tremendous amount of heat and so roots are less likely to suffer from freeze/ thaw cycles. This also makes the roots less cold hardy than the stems/ leaves. With their roots in the ground they are substantially better protected but not in pots. Protecting plants in pots is therefore essential to their survival. The less water there is in the soil the less likely the soil will freeze and kill the roots. Less water equals higher levels of manufactured anti-freeze in the plants.
Applying a layer of mulch around pots can be very beneficial. This will protect the soil surface and provide insulation for the roots. Snow will do this too but this is where we risk plant loss at our sea level, west coast climate. Snow can be here today, gone tomorrow.
The last few weeks have seen the temperatures fluctuate from highs of 15C to lows of -5C or worse. Its a lot for some plants to handle.
Just like us, too much stress is not a good thing.
I leave you with this quote from Goethe- " In observing Nature on a scale large or small, I have always asked: who speaks here, the object or you ?"
Winter hardy plants have an ability to produce minimally required amounts of anti-freeze within their tissues. As it freezes the plant begins to decrease its' water content and transform it into anti-freeze. It is still not clearly understood how it does this. Suffice to say that it requires a lot of energy from the plant to accomplish this.
Cold-hardiness is mostly genetically pre-determined. Over time and by saving seeds and adapting each generation to the local temperature fluctuations it is possible to have certain varieties become more tolerant to cold.
I have a bay laurel that should NOT have survived the cold of -17C a few years ago. I started it from a cutting many years ago and for the first 5 years or so of its' life here at Ironwood Farm I took extra care to wrap and cover it during the winter. It was only after 5 or so years that I risked leaving it to fend for itself. It survived even though it looked a mess. I had to severely prune out 3 feet of its' height and a lot of its' width. But wonder upon wonders there was new growth sprouting out from the bottom !!
Soils hold a tremendous amount of heat and so roots are less likely to suffer from freeze/ thaw cycles. This also makes the roots less cold hardy than the stems/ leaves. With their roots in the ground they are substantially better protected but not in pots. Protecting plants in pots is therefore essential to their survival. The less water there is in the soil the less likely the soil will freeze and kill the roots. Less water equals higher levels of manufactured anti-freeze in the plants.
Applying a layer of mulch around pots can be very beneficial. This will protect the soil surface and provide insulation for the roots. Snow will do this too but this is where we risk plant loss at our sea level, west coast climate. Snow can be here today, gone tomorrow.
The last few weeks have seen the temperatures fluctuate from highs of 15C to lows of -5C or worse. Its a lot for some plants to handle.
Just like us, too much stress is not a good thing.
I leave you with this quote from Goethe- " In observing Nature on a scale large or small, I have always asked: who speaks here, the object or you ?"
