SV: hardiness

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As I actually grow relatively few species, my experience is limited for the Cologne area.  We are typically a Zone 8, but the last two winters have been severe with temps dipping down to -15°C for a week at a time with little snow cover.  Enough to test the hardiness of some plants.

I found that Louisiana species cannot take this in the ground, but have no problem in water.  I. fulva dies at -8°C in the ground, as do most hybrids.  The soil is sandy clay and stays quite wet during the freeze-thaw cycles.

I. confusa and I. japonica do not survive any of my winters.  The wet freeze-thaw does them in, I think.

Pacific Coast species, such as I. douglasiana and I. tenax have not trouble.  I have a few more seedlings currently frozen in ice that look fine during the brief thaws.

I have yet to loose any aril species, despite the wet winters, but I only have I. sari, I. elegantissima, I. acutiloba, I. stolonifera, I. hoogiana, I. korolkowii, I. lineata and I. meda at the moment. These plants are in pots on a protected, south facing balcony.

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Jamie V.

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Köln (Cologne)

Germany

Zone 8