Hardy pygmies

[manders]

Hi, does anybody know of a list of frost hardy pygmies?

[diva]

i dont have a list but scopiodes and pulchella thrive in my greenhouses (at one point they were like capensis weeds!) which is unheated.

[Sean Spence]

I'm not sure how severe the frosts are that you receive, but I had grown a large range of pygmy Drosera species outdoors (with no shelter at all) over a period of years and temps here often get down to 0 C at night (sometimes down to -2 C). We get quite a few frosts per year and none of my plants ever showed any ill effects.

[manders]

Thanks Diva and Sean,

Maybe they can all stand some frost then? Sean, around here we get a few days per year around -2 and the occasional drop to -7 but that's fairly rare. They'll be in an unheated greenhouse. I grew lake badgerup outside for a few years and that was fine, wasn't sure about any others though.

[Dieter]

In my experience adult plants easily survive frosts down to -5°C in pots frozen solid for days. Youngsters (from sprouting gemmae) and free gemmae (those no longer attached to the parent plant) are not that hardy and will die much more easily.

Best regards

Dieter

[manders]

Update after the frosts...

We got to -8C outside and at least -5C inside the greenhouse. Most of the pygmies seem fine, the only exceptions are some pulchellas and ericksoonia*pulchella which are badly frosted, probably dead. Strangely some pots of pulchella seem ok and other pots are wasted. In the 'wasted pots' the gemmae that were on the now dead plants look green and viable. A winter adaptation for species survival maybe?

[will9]

Update after the frosts...

We got to -8C outside and at least -5C inside the greenhouse. Most of the pygmies seem fine, the only exceptions are some pulchellas and ericksoonia*pulchella which are badly frosted, probably dead. Strangely some pots of pulchella seem ok and other pots are wasted. In the 'wasted pots' the gemmae that were on the now dead plants look green and viable. A winter adaptation for species survival maybe?

I think you must wait till plants came again in grow for seeing wat is still alive ,frozen plants looks very well so long she are frozen and not in grow but can died very fast after the cold periode and after winter when she came back alive,i hope she are still alive after winter.Please let us know then,i am really intresting in how the plants react on this,

cheers Will

[jimscott]

I have had my whole pygmy collection receive light frosts. The hardiest were the pyulchella x omissa, carburups and badgerups. It does seem to correlate that the crosses do the best.

[manders]

We eventually got around -7 or maybe lower in the greenhouse, practically non of the pygmies survived. Oddly enough out of a pot of a 100 or so callistos, just one or two are showing signs of growth, the rest are dead.

[Dieter]

Outsch!

So a few degrees of frost are tolerated but there seems to be a limit around the -5°C.

Best regards

Dieter

[Rob-Rah]

Plants in a greenhouse usually don't receive "frost" as such. Frosts happen when water vapour in the air freezes on the leaves of plants. This in turn provides nucleii for ice to form on and in the plant's tissues, and which makes them freeze as well. When the plant tissues freeze, the water in the cells expands and the cells burst due to the increased pressure and ice crystals puncturing them. Then the plant is dead.

In a greenhouse, even when the temperature gets below freezing, you tend not to have the nucleating vapour. The lack of nucleii for ice to form around means that plant tissues may go to below freezing but no ice forms in the tissues, so the cells do not burst, and the plant stays alive. You have supercooled water in the plant tissues instead.

At a certain temperature below freezing this effect will stop and the tissues will freeze anyway. Normally somewhere between -4C and -12C.

However, temperatures themselves don't tell you a complete story about what plants will tolerate! The effect of physical frost, and the effect of relative humidity is highly relevant.

Interestingly, certain bacteria can precopitate the nucleation of ice crystals in plant tissues at higher temperatures, and hence make the plants less able to tolerate cold temperatures: http://www.ncbi.nlm.nih.gov/pmc/articles/P...30/?tool=pubmed

Cheers.

Rob.