Report from the trial beds: Delosperma overwintering

Last summer, I took an unused section of the nursery and turned it into what we're calling the trial beds. The idea is to set out big sections of our collection side-by-side so visitors to the nursery can easily see what they look like in the ground, compare different species and cultivars, and get an instant education on groups of cool plants they might not have ever heard of.

Here is what they looked like just getting started last summer. The first bed has our entire collections of dracocephalum, scutellaria, teucrium (about a dozen species of each), along with some dwarf gypsophila and onosmas. The second bed is our entire collection of Penstemon (clocking in at no fewer than 45 different species and varieties... Yeah. That is a lot.) and the third, not finished in this photo, has asperula, erodiums, and delospermas. Three more beds will hopefully get planted up this summer. (Got a genus or group of plants you'd be curious to see grown out this way? Let me know in the comments and I might be persuaded to put them in for you.)

If you are local, I hope you'll come by and check them out over the course of the summer -- I think they're going to be pretty darn cool. But, since most of you AREN'T local, I'm going to try and give regular reports on what I'm seeing in the trial beds here on the blog.
First up, Delosperma overwintering. Most of the varieties of delosperma we grow are supposed to be hardy. And most of them ARE, provided they are kept nice and dry. Cold doesn't usually kill them, but winter wet certainly does. So I was interested to see what could actually make it through our wet Michigan winter. We do have very sandy soil at Arrowhead, which helps enormously (don't expect this sort of overwintering success if you have heavy clay) but as you can see, these aren't raised beds or rock gardens to give extra good drainage.

So, here are the survivors:

Delosperma eckolonis v. latifolia
D. cooperi 'Dwarf' (Note that the normal D. cooperi did NOT survive)
D. 'Firespinner' (so excited about this one... gorgeous in flower. I'll share later once they start blooming)
D. sphalmanthoides
D. basuticum
D. aff. nubigeanum (If you are unfamiliar with "aff." if basically means that is the name the plant came with, but we're not sure that is really what it is. Honestly we could probably put that on almost ALL the delospermas... Notoriously mixed up in the trade, and hard to figure out if you are not an expert in the genus. Which I'm not.)
D. aff. congestum
D. 'Broncoensis'
D. congestum 'Gold Nugget'
D. deleeuwiae
D. 'Lesoto Pink'

This is, honestly, a much longer list than I was expecting, over half of the plants I put in the ground! It is only data from one winter, of course, but it was a fairly cold winter. Temperatures dropped to -10 F and STAYED there for a few days, with almost no snow cover, in the process killing more than a few plants that had been hardy in the garden for years. Arrowhead sits just on the edge of zone 5 and zone 6 on the new USDA hardiness map, which means that around -10F has been our average winter low for the past 30 years, so this was a fairly representative winter, though of course we can get much colder... there was the year of -26 F, but hopefully we won't see that again for a long time.

I took pictures of all the surviving plants, but honestly they all pretty much look like this one of 'Gold Nugget'

Not much to see at the moment. But I'll follow up with pictures of each of the survivors once they start flowering, and hopefully keep tabs on them on and off through the summer so you can see how they spread, and which ones rebloom.