The lowest temperatures are here and for the coming 4 days the forecast is to have as low as -23 °C at night. I worry about my North American burstgrowers and other frost hardy along with them. None of them has been exposed to anything lower than -15 °C (except Pediocactus knowltonii with a personal record of -18 °C). I am not eager to have them have new personal records, but I also don't know if just a few days with bitter cold night temperatures matter much for them (day temperatures are expected to be around -10 °C).
The plants have just a basic protection provided by a sheet of PE over. They are in pots, the soil is tinder dry since October last year. Could they take this cold or I should move them indoors for a few days?
Some of the plants have their first winter outside. Here is the list (* = first year exposed to frost/hardiness not tested):
Echinocereus fendleri SB51 Caballo Mountains, Sierra Co., NM, USA
*Echinocereus nicholii
*Echinocereus russanthus SB420 Brewster Co., TX, USA
*Echinocereus triglochidiatus SB104 Sandia Mountains, Bernalillo Co., NM, USA
*Echinocereus viridiflorus ssp. chloranthus
*Escobaria missouriensis ssp. missouriensis var. missouriensis
*Escobaria missouriensis ssp. missouriensis var. similis
*Escobaria sneedii ssp. sneedii var. leei SB397 Eddy Co., NM, USA
*Escobaria sneedii ssp. sneedii var. sneedii
*Escobaria vivipara var. neomexicana SB129 Manzano Mountains, Socorro Co., NM, USA
*Pediocactus bradyi ssp. winklerii RP102 Wayne County, UT, USA
Pediocactus knowltonii SB304 San Juan Co., NM, USA
Pediocactus nigrispinus HK1203 Kittitas Co., WA, USA
Pediocactus paradinei SB502 Coconino Co., AZ, USA
*Pediocactus peeblesianus ssp. peeblesianus var. peeblesianus SB571 Navajo Co., AZ, USA
*Pediocactus peeblesianus ssp. fickeiseniorum var. fickeiseniorum RP145 Wolf Hole, Mohave Co, AZ, USA
*Pediocactus sileri SB1872 Saint George, Washington Co., UT, USA
*Pediocactus simpsonii var. simpsonii RP110 Burntfork, Sweetwater Co., WY, USA
Pediocactus simpsonii var. minor
Sclerocactus mesae-verdae SB303 Shiprock, San Juan Co., NM, USA
(Edit: fix the topic subject after the forum version upgrade).
Can they take -23 °C at night for a few days?
Can they take -23 °C at night for a few days?
Last edited by exotica on Sat Feb 11, 2012 10:52 pm, edited 1 time in total.
Cheers, Andrey
Andrey, is PE polyethylene (polythene) sheet? My understanding is that stuff in contact with plants in cold weather can result in freeze burns. This is from the Texas A&M University agricultural extension service:
"Plastic sheeting or any material that radiates its heat out quickly will “burn” (actually freeze) plant tissues where it touches them. It also tends to not reflect the radiant heat back down as well. Plastic is good, however, in holding in the air on a windy night so if you cover the plastic with a blanket or sheet you can increase the amount of heat reflected back to the plant and soil."
Here's the link: http://aggie-horticulture.tamu.edu/trav ... reezes.pdf
"Plastic sheeting or any material that radiates its heat out quickly will “burn” (actually freeze) plant tissues where it touches them. It also tends to not reflect the radiant heat back down as well. Plastic is good, however, in holding in the air on a windy night so if you cover the plastic with a blanket or sheet you can increase the amount of heat reflected back to the plant and soil."
Here's the link: http://aggie-horticulture.tamu.edu/trav ... reezes.pdf
A new record low for the date (-22 °C) in Sofia.Strangely enough, one that I would worry about is P. peeblesianus. Most Pediocactus should be safe to -20C or better, but this is less hardy.
Some named E. vivipara varieties are not especially hardy. I thought var neomexicana was one but Mesa gives it an 18 code.
Then perhaps Escobaroa sneedii would be next on the list of things to protect.
I've lost a couple of the Echinocereus you mention at much warmer temperatures but they were wet. E. nicholii would be suspect.
Some named E. vivipara varieties are not especially hardy. I thought var neomexicana was one but Mesa gives it an 18 code.
Then perhaps Escobaroa sneedii would be next on the list of things to protect.
I've lost a couple of the Echinocereus you mention at much warmer temperatures but they were wet. E. nicholii would be suspect.
--ian
I'm sure that the way the plants are situated (and having a cover), the temperature is higher. I didn't have a min/max thermometer to put in the "micro environment", so I don't know what they've been exposed to, but I've just purchased one and tomorrow I'll have it (it is a mercury one, said to be made in Germany). In Thursday, peak low temperatures are expected, so I'll have some "true" temperature readings on record (right now I'm watching my outdoor thermometer, which is mounted 1.5 m above the plants).
My biggest concern are the 2 peeblesianus ssp's and mostly sileri, but I can get substitutes in case I lose them (so as for the other test plants). The simpsonii from WY will certainly pass the exam. From the other plants, I expect the triglochidiatus to pass it too. The rest - I'll know soon. And I'll share, of course.
A little OT is that I'm pushing to extremes 2 south Americans, which survived last year's -15 °C, but with frost damages - Tephrocactus articulatus var. inermis and var. papyracanthus. They didn't have any cover. They gave splendid new segments even from the worst frostbitten areas.
My biggest concern are the 2 peeblesianus ssp's and mostly sileri, but I can get substitutes in case I lose them (so as for the other test plants). The simpsonii from WY will certainly pass the exam. From the other plants, I expect the triglochidiatus to pass it too. The rest - I'll know soon. And I'll share, of course.
A little OT is that I'm pushing to extremes 2 south Americans, which survived last year's -15 °C, but with frost damages - Tephrocactus articulatus var. inermis and var. papyracanthus. They didn't have any cover. They gave splendid new segments even from the worst frostbitten areas.
Cheers, Andrey
I've just got the first few °C above 0 today. I've also got my min/max thermometer, but the coldest night was gone (31.01.2012). Anyway, we had record lows in 4 consecutive days.
Today I checked the condition of my test plants, but saw nothing wrong. Completely shrunken healthy bodies.
The 2 Tephro had some signs of frostbites, but most of the segments' epidermis looks fine. It will show later.
I'll be getting a camera in the coming few days, so I'll post some pictures.
Today I checked the condition of my test plants, but saw nothing wrong. Completely shrunken healthy bodies.
The 2 Tephro had some signs of frostbites, but most of the segments' epidermis looks fine. It will show later.
I'll be getting a camera in the coming few days, so I'll post some pictures.
Cheers, Andrey