The vast majority of cacti (including most of the cold hardy genera) are germinated routinely and easily at average room or under lights temperatures. There don't seem to be many exceptions, but Pediocactus is definitely one of them, Sclerocactus and Toumeya are grouped with it by Mesa Gardens among others... Some Opuntias are reputed to have seed age/delayed germination issues (I've hear of seed coming up 9 years later, but have no personal experience to back it up).. An easy family overall, but with a few difficult children! Cohan
On Fri, Feb 4, 2011 at 12:36 PM, Pacific Rim <[email protected]> wrote: > I stumbled on this paper on cactus germination and propagation > http://opuntiads.com/zpdf/cactus-review.pdf while looking for N American > Clematis seeds for a Japanese correspondent. > > It reinforces some statements made recently on this list and undermines > others. But it was published way back in 2000. Perhaps every fact in it has > been overthrown since then. Cacti are outside my expertise (as is > everything > else, come to think of it). > > An extract: > ============== > ... some observations can be made of the temperature effect on cacti seed > germination: > > (1) Temperature extremes do not favour germination, that is, below 123C and > above283C. A temperature of 20$23C gives a good germination rate in a wide > range > of genera. > > (2) Different species have different responses to temperature. > > (3) Time to complete germination decreases as temperature increases (i.e. > Astrophytum myriostigma and Gymnocalycium mihanovichii). > > (4) Response to temperature depends on seed age (i.e. the optimum > temperature for 1 year old seeds is lower than for the 7 year old seeds of > Parodia > chrysacanthion). > > (5) Aged seeds take longer to germinate than young ones (e.g. Maihuenia > poeppigii). > > (6) Alternating temperatures give better germination results than constant > temperatures. > > Despite this last statement, alternating temperature effects on cactus seed > germination are not very clear ... > ===================== > Gibberellic acid is mentioned, too, but I won't go there now. > > Growers of Trillium learn "myrmecochory" early: it means seed distribution > by ants. This paper reminds us that myrmecochory is a mere sub-subcategory > of zoochory -- seed distribution by animals. If your dog carries a burr, > that is epizoochory. If seeds are carried off by a flash flood, that is > hydrochory. My new favorite is anemochory -- distribution of seeds by wind. > As in anemone, the windflower, yes. > > Paige > > West Central Alberta, Canada, Zone 2-3 record temps from 10-20 miles away: min -45C/-49F;max 34C/93F http://picasaweb.google.com/cactuscactus
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