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Via An Iowa Garden)
Posted by admin to Uncategorized on 2008-01-03, 11:08:00
There are lots of ways to classify primroses; in my experience, they can all be grouped as follows: those which don't like our cold winters, those that don't like our hot summers, and the largest group... those that don't like either one. I must confess to being irked to no end by the fact that the Juneau chapter of the American Primrose Society, is one of the largest and most active, though admittedly we're talking south coastal Alaska here. Still, I tend to get very whiny when considering that gardeners in Alaska have to take a hoe to primroses the size of cabbages to keep them from taking over their gardens, while here in Iowa (the farm state), most primulas look like recent escapees from a herbicide test plot. Fairness is a scarce commodity in gardening.
Although there is over a foot of snow on the ground here currently, let us then consider one facet of primrose hardiness: which are the most heat-tolerant here?
Primula sieboldii might be the best, by virtue of the fact that it goes dormant in the heat of July, and stays there until the next spring... a wise plant, indeed. My second place finisher up until recently would have been Primula kisoana; a Japanese species built to take the heat, with thick, very hairy leaves and stems. However, the freakish late freeze last spring killed 90% of the kisoanas in the garden: turned them to mush. I had grown this species for ten years without losing a single plant prior to that, and it was spreading all around. Several friends to whom I had given offsets said they'd lost them altogether. Now I know we are supposed to be considering just heat tolerance, but the plant has to survive until summer to judge that. Another primrose to consider would be Primula veris, the cowslip of Great Britain. There are three common wild primroses of the fields and woods in Great Britain; P. veris (the Cowslip), P. elatior (the oxlip), and P. vulgaris (the common primrose). They also are endemic across temperate continental Europe, with veris extending into western Asia.
Veris is a primrose more of the open fields, with its native range extending down into southern Russia, so it is thought therefore to be fairly heat tolerant, being able to thrive down into the Carolinas here in our country, and so I am in the process of thinking more critically about its potential here in our Iowa garden. This process is complicated somewhat by the fact that veris, elatior, and vulgaris have all been extensively interbred in nurseries, and pure species, at least in this country, are probably not very often sold in mainstream commerce. Oftentimes, therefore, one sees them sold as Primula polyantha (mainly hybrids between veris and vulgaris), and Primula acaulis (which have a lot of vulgaris blood). Veris and elatior have their flowers arising in clusters (umbellate) from taller stems, so their hybrids with this flowering pattern are called polyanthas. Vulgaris has its flowers more or less singly on shorter, multiple stems (which is called 'acauloid'). All three of these species suffer a bit from in the wild basically occurring in... yellow, which for some reason is my least favorite primrose color. Elatior tend to be a creamier, lighter yellow, veris a brighter, deeper yellow, and vulgaris, I think, kind of runs the gamut. Fortunately veris does occasionally occur in red shades, so for example, you can buy P. veris Sunset Shades, a strain selected for its orange-red hues, shown in the top picture. I just obtained my first plant of this a couple of years ago, and haven't fully evaluated it yet for hardiness, but I sure like its looks, though I suspect it is a hybrid of veris and elatior. The second picture shows a primrose with flower color more typical of veris, but is probably also a hybrid, and it is in fact labelled Primula polyanthus. The bottom picture is also a hybrid ('Butterball'); while it is umbellate, it has shorter stems, and probably has vulgaris blood in it, while the pale, creamy yellow looks like elatior.
So, the primulas we buy at the nursery of these species are probably more of a spectrum of hybrids and species, but they are all nice, and I plan on growing and better evaluating more of them, especially the Sunset Shades.
