Texas weather, freeze susceptibility, sand plunge
Monica Swartz (Sun, 26 Jan 2014 21:28:13 PST)
Cynthia asked about how winter-growing bulbs respond to the
temperature turmoil in Texas. I live in Austin (zone 8b) though the
microclimate at my house on the edge of the escarpment is
significantly more extreme than in the city. I grow hundreds of
winter-growing species from S. Africa, California, and the
Mediterranean, most with little to no weather protection and I've
been planting loads of winter-growing bulbs into the ground to see
what works.
This winter has provided several events with 80 degree F temperature
swings in 24-48 hours and one rainfall event of over 15 inches in a
few hours. The plants grow when the weather is good, and pause when
it is not. The wild swings in temperature make no difference in when
they flower or go dormant. In my experience, most winter-growers are
far more freeze-hardy than you might expect.
The real killer this year was the first freeze in mid November. I
lost several species and had lots of damage even though it was barely
below freezing. It simply hadn't been cold up to that day and I
believe that the plants need the trigger of some cool nights to make
the heat-shock proteins that protect them. A mild freeze out of the
blue was far more deadly than the recent 15 degree ice storm.
I have only been growing in Texas for a few years and I still have a
lot to learn. This November's lesson was a hard one. On a brighter
note, I've also learned how fantastic a sand plunge is!!! I built a
small plunge in full sun for winter-growing Brunsvigia, Haemanthus,
Boophane, and Gethyllis and all are growing and flowering happily
without the freeze damage shown by the same species on shelves just a
foot away. I think they could go below 10 degrees F before the first
leaf burn on the edges. Even more surprising is that I left the pots
in the plunge all year and let them get summer rain without cover.
They loved it, lots of flowers (the Brunsvigia seed I sent to the BX
came from this plunge) and one Gethyllis split into three. Our rain
is infrequent but heavy (35 inches a year on average). Those of you
in drier climates should have little to fear. I have read about sand
plunges on this forum for years and now I'm more than convinced, I've
started building my second one.
monica expecting more snow tomorrow after 75 F today