Monday, January 26, 2015

Blogging before the Blizzard--Testing South African Plants for Cold Hardiness

Oxalis melanosticta w/ O. pocockiae nearby

Oxalis stenorrhynca

Brunsvigia radulosa

Asparagus sp from Plant Delights

Sparaxis elegans

Diospyros lyciodes
These photos were taken earlier in late December when we already had had some quite cold nights and some snowfall.  All of the species depicted are in protected spots near the southeast facing wall of the house, and the Oxalis spp have been there since before last winter.  The O. melanosticta bloomed earlier this fall, as did the stenorrhynca, although the stenorrhynca foliage is more sensitive to very low temperatures than melansticta, it does come up earlier, in August so it can get a lot of growing out of the way before its frosted back.  By the way, I often see O. melanosticta misidentified as a yellow form of O purpurea under the name Ken Aslet, but it is most definitely not O purpurea.  The latter itself is a very variable species but does not resemble O. melanosticta in the least.  Nearby a species of Asparagus from Plant Delights nursery has kept its foliage through several frosts but before we got down to single digits it was covered with dry grass/straw along with most of the others, and when I peaked during a milder spell it seems to have lost most of its foliage except near the base.  I don't expect the top to make it through winter but hope it will resprout when warmer weather comes in spring.  On the other side of the stairs by the front door I set up a small mostly South African garden, there small seedlings of Diospyros lyciodes are planted, it should make it through as a dieback shrub based on past experience with this species.  I have numerous seedlings of Brugmansia radula so I am testing a handful outside, although it comes from summer growing areas it tends to leaf out for winter.  It comes from some pretty high altitudes and the leaves appeared fine when I last checked them, though I do worry as it has a shallow rooted bulb so it will have to stand prolonged freezing before it can be judged how much cold it can take.  Sparaxis elegans is from the Niewoudtville area and would be expected to tolerate some frost, but probably does not experience as much as it will get here.  As some compensation it is placed right by the wall of the house where it doesn't freeze so deeply. 
We will experience some harsh cold next week, but before it arrives we expect a "historic" blizzard commencing tonight.  School is already closed and some light snowfall is occurring right now well before the big event.  Leaves and straw cover many of the zone pushing plants along the sunny front walls of the house from before the last dip to low single digits F, so with the added snow insulation that we have largely lacked till recently I expect many species will come through.  Among other zone testing plants out in the gardens this winter is one big Erythrina zeyheri, Erythrina x bidwellii, another SA Asparagus spp, two of the so called Drakensberg gerbera hybrids, Tulbagia violacea, 2 different Hedychium spp and the hybrid that made it through last winter, Acanthus sennii, Amorphophallus sp (probably konjac), and no doubt some others that are escaping my mind at the moment.  In one of the back gardens Euryops evansii is taking a bit of a beating, it is alive but I hope it regenerates well in spring, it is not protected as it does grow at very high elevations in the Drakensberg.  Most evergreen kniphofias look good as we go into the blizzard with minimal if any dieback, the snow should prevent further dieback since by the time it melts it will probably be mid February at least and we should be past the single digit night lows.   Or at least I hope so.

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