Not so hardy Agave

[Keith H]

I am amazed by how many plants some of our experienced growers have lost this winter, I know we all expect the odd loss but did we all become complacent after a run of mild ish winters?
I am not that far from Mike is SE London and know we have had both colder nights and more snow in previous years but I can not remember such long periods of below freezing nights with daytime temperatures staying below or just above freezing.
I try to keep my greenhouse at or around 5 deg. C and I am trying not to think about the amount of electricity I will have used this year but so far I think I had more losses last year when the air in the greenhouse was damper.
Here's hoping for a mild spring and another hot summer, fingers crossed.

[Paul in Essex]

I believe it is all down to the peculiar timing of events this year. This year's long hot summer made a lot of stuff go dormant. Then came a really long, mild and exceptionally wet autumn and an awful lot of the garden succulents thought it was spring again! They were actively growing when, bam, -6C and a week long freeze. It was particularly bad for those more temperate species. I think the more xeric, heat loving plants had already started to go dormant by the time the cold came but plants like Agave montana, which I would have previously bet the house on, were still growing and this got hammered. Disappointing but that's how we learn.

[el48tel]

I believe it is all down to the peculiar timing of events this year. This year's long hot summer made a lot of stuff go dormant. Then came a really long, mild and exceptionally wet autumn and an awful lot of the garden succulents thought it was spring again! They were actively growing when, bam, -6C and a week long freeze. It was particularly bad for those more temperate species. I think the more xeric, heat loving plants had already started to go dormant by the time the cold came but plants like Agave montana, which I would have previously bet the house on, were still growing and this got hammered. Disappointing but that's how we learn.

I don't think you could sum it up more succinctly.

[MikeT]

I believe it is all down to the peculiar timing of events this year. This year's long hot summer made a lot of stuff go dormant. Then came a really long, mild and exceptionally wet autumn and an awful lot of the garden succulents thought it was spring again! They were actively growing when, bam, -6C and a week long freeze. It was particularly bad for those more temperate species. I think the more xeric, heat loving plants had already started to go dormant by the time the cold came but plants like Agave montana, which I would have previously bet the house on, were still growing and this got hammered. Disappointing but that's how we learn.

That would fit well with losing lots of Aeoniums which had survived similar temperatures easily in previous winters.

[NorfolkExotics]

I was surprised to find that the main species showing damage for me is A. americana, which is theoretically hardy to -9 depending on the clone. Species that should less cold tolerant like titanota, oteroi, potatorum and somehow even isthmensis are fine so far. The lowest it got in my garden was -4 and everything in my greenhouse was fleeced. The idea that the timing of the cold caused the damage seems logical to me also. I assume the americana were still active when the weather from hell arrived while the oteroi, potatorum etc. had already shut down owing to them coming from a more xeric habitat. Here's hoping it doesn't get that cold again for the rest of the winter...

[edds]

I believe it is all down to the peculiar timing of events this year. This year's long hot summer made a lot of stuff go dormant. Then came a really long, mild and exceptionally wet autumn and an awful lot of the garden succulents thought it was spring again! They were actively growing when, bam, -6C and a week long freeze. It was particularly bad for those more temperate species. I think the more xeric, heat loving plants had already started to go dormant by the time the cold came but plants like Agave montana, which I would have previously bet the house on, were still growing and this got hammered. Disappointing but that's how we learn.

Totally agree.

I have two trays of three year old Agave plants in my cold greenhouse. One is full of montana and the other parryi. The montana are all dead, the parryi are all fine, even ones that were looking a bit dodgy before the cold spell! I think the montana were growing away happily when the freeze happened whereas the parryi had stopped. The greenhouse only went down to -4C.

I don't think this run of cold weather was particularly harsh or long for the North and Midlands - we have a similar spell most winters i can remember. Last year was exceptionally mild however.

[Mike P]

Last time we had the same December freeze was 2008/9 when I lost a number of plants outdoors including several of the more tender Americana variegates. I also lost a lot of slightly tender Tree ferns and Mediterranean types plants which the run of hot summers / mild winters in the early 00’s encouraged us all to grow…I blamed Alan Tichmarsh. A few losses every 12-13 years seems a risk worth taking to me. I can live with growing a nice new blue macroacantha as long as I can track one down.

[SimonT]

I have a small unheated cold frame that I use for isolating plants or treating sick ones.
After the mild winter last year I decided to keep the sick plants with a few spare seedlings in the frame to see how they did over winter. As it turned out the cold frame has been down to -7oC (so far) and was frosted for a long spell and during this time the lid was open a few cm as well. Not quite what I was hoping for over the winter. I did use a fleece for a while but then took it out because I was worried about condensation.

The frost did turn a few of the plants to mush- I lost a M. guelzowiana that I was treating as well as a small R. muscula. But I have multiple R. pumila, R. flavistyla and Rebutia heliosa v teresae two year old plants that look OK, as well as some other Rebutia plants. Maybe some will mark or die later on when I start watering, but they are not discoloured or mush so far. I know that R. pumila and R.flavistyla are both pretty tough- the plants I obtained my seed from survived 40+ years in an unheated conservatory. I dried off all these plants before winter but some could have got wet after this I suppose.

I noticed that R. pumila, R. flavistyla and R. heliosa were on the list of dead plants- it is interesting that we have had different experiences with these?

[Keith H]

Last time we had the same December freeze was 2008/9 when I lost a number of plants outdoors including several of the more tender Americana variegates. I also lost a lot of slightly tender Tree ferns and Mediterranean types plants which the run of hot summers / mild winters in the early 00’s encouraged us all to grow…I blamed Alan Tichmarsh. A few losses every 12-13 years seems a risk worth taking to me. I can live with growing a nice new blue macroacantha as long as I can track one down.

Thank you Mike, we were trying to remember when the last really cold winter was, most of my plants were still with my Father in Yorkshire but I did have a few on the window sills and in the front porch. The Americana that used to come into the porch every winter had grown too large and for several years stayed outside and was doing rather well until that winter. I have not been up to the Horniman to see how their dry garden has coped but remember they lost the Agaves planted on the gate posts at the Horniman drive entrance that last really cold year.

[Mike P]

On a positive note I’m hoping the repeated freezing and relatively bright weather might prompt the Mamm senilis to produce more flowers this year.