Delosperma update: The field narrows

Back in May, I posted about my experiments with trying to kill delospermas. I planted out entire collection out during the summer of 2012, in our native sandy soil, but no special conditions like raised beds or anything else. My goal was to see what THRIVES here in Michigan with no extra effort, so I just plopped two plant of each variety in the ground and waited to see what happened.

In May, I reported that 11 species had come through the winter just fine -- over half of what I had planted out to begin with. Which was more than I expected. I was surprised to find that over the summer many more bit the dust. We're now down to just 5. We had a summer that was slightly on the rainy and cool side, but nothing extreme. I never would have guessed it would kill so many delospermas. But it has, leaving me with a narrowing field of the very best delospermas for the Michigan garden. Here are the survivors, with pictures of what they look like today, with my comments:

Delosperma 'Firespinner'

This CLEARLY wins the vigor contest. This was a little, MAYBE 2 inch across plant just one year ago, and now the patch has spread to nearly two feet across. Way to large and aggressive for a rock garden or other small garden, but if you want a vigorous tough ground covering delosperma, this is the one I'd recommend. The flowers are stunning red-orange bicolor. (Sorry, we don't have this listed in the catalog yet, but should have some ready for sale by spring. If not, you shouldn't have trouble finding it for sale... everyone is growing this beauty.)

Delosperma ecklonis v. latifolia

Coming in a close second on the vigor department, this one has gone from two inches to a foot and half in just one year. Typical bright magenta flowers, heavy blooming in the early summer, with quite decent rebloom. As you can see, it hasn't quite given up flowering now, in NOVEMBER, despite quite a dose of freezing weather.

Delosperma deleeuwiae (possibly actually D. neill)

Delosperma 'Broncoensis'

Delosperma 'Lesotho Pink'

Not much practical difference between these three... all spread from their original ~2 inches to 6 or 8 inches, intense magenta flowers. Most of the plants in the garden suffered some die back in the centers of the clump, which gives them a bit of a patchy look. 'Broncoensis' is probably the best looking plant of the bunch (Note: we don't have this in the catalog at the moment. Stand by, we should have some ready to list soon.) and better for a small space than 'Firespinner' or D. ecklonis.

Delosperma nubigenum (this name may be incorrect...)

This is one of my favorites. The plant stayed quite small and tight, barely getting to 4 inches from the original 2 inch plant, which means this would be terrific in a rock garden or container garden. Yellow flowers, which is always a nice change from the typical delosperma magenta, and the foliage is taking on this lovely red flush as we're getting into fall. Apparently turning red in the fall is normal for most delospermas in sunnier climes like Denver, but here, where fall is cloudy and rainy, it is the only one really worth looking at.

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.