A Coreopsis revolution

[TheOnionMan]

In mid September (2010) I had the distinct privilege of visiting Darrell Probst's hybrid fields, but I'm not talking about Epimedium here, this time around it was to walk a field of 5000 hybrid Coreopsis seedlings.  The seedling field represents 10 years of hybridization efforts in hardy Coreopsis.  The key phrase here is hardy Coreopsis, as many of the recent hybrids that have flooded the market, such as 'Sweet Dreams', 'Limerock Ruby', are crosses made with annual C. tinctoria, resulting in plants that are just not reliably hardy in USDA Zone 5.  The lack of hardiness and performance on a number of Coreopsis hybrids has left many gardeners jaded (myself included), and wary of trying more because of their unreliability.

In contrast, Darrell searched out and found many hardy Coreopsis species that were not in cultivation, to add to his hybridization efforts. And of course, he also utilizing the familiar Coreopsis rosea (native to Massachusetts), which has been used in Coreopsis breeding before, but remains an exceedingly difficult species with which to make successful interspecific crosses.

Driving to Darrell's field located in western Massachusetts, I tried to imagine what the hybrids would look like, but I was totally unprepared for the astonishing range of hybrids he managed to come up with. Walking the long rows upon rows of amazing hybrids was like being in a living science laboratory, with all of the lessons of botany, genetics, and hybridization just sitting there within the plants looking up at me, it has been a long time since I've been so inspired. Visiting the field was educational in so many ways, here are a few observations:

1.  It takes vision, great tenacity, and years of determination to get worthwhile results.

2.  It requires gathering and exploring as wide a gene pool as possible, to truly explore the possibilities.

3.  It requires LOTS & LOTS of space and thousands of seedlings yearly, to achieve sufficient diversity (and nuances within that diversity), to be able to pick out the best of the best.

4.  Incredible effort and expense goes into such seemingly simple endeavors.

Let me take you through a small photographic journey of Darrell's Hardy Coreopsis trials.  Some of his best groups of hybrids, such as the thread-leaf ones (verticillata group), I'm not at liberty to show (I can assure you they're amazing), but there's lots here to illustrate the process and achievements.

[TheOnionMan]

Darrell Probst uses hired resources to grow on his seedlings and create plugs ready for planting, then uses the farm (owner of the fields) to quasi-mechanically plant out his plugs in long rows 3 plants wide, inserted into holes in plastic weed barrier.  All the flowering plants shown here, in full flower in September, represent the first year of growth, Coreopsis are quick growers!  All plants grown are reviewed by Darrell of course, but other invited parties as well, and flagged (literally) to indicate selected plants. Anything that gets selected is then propagated by cuttings and trial-grown, all seedling plants get plowed under to start the hybrid process afresh next
spring.

1.   view of the fields near the end (these are L-O-N-G rows).
2.   view of red-centered types.  There are already some of these on the market, but in the
      next series of photos, you'll see there is still lots of diversity.
3.   A selected plant, with very rotate flowers, strong red eye zone, floriferous, good habit
4.   two variants of a theme, red centers to yellow flowers, but very different
5.   really nice compact yellow and red-eye type, with the pronounced 8-petal effect, with 4 lobes to each petal, I really like these types.  Passed up by those who reviewed the plants.
6.   fantastic to see plants side by side, in the center is a really terrific dwarf type compared to taller siblings around. The one behind it is even smaller.
7.   same view as #6 above, but in the background we see a lovely dwarf cream hybrid.
8-9  side by side, two similar colored seedlings, but the one on the left is really dwarf!
10   oooh, some red ones!

[TheOnionMan]

11-12 Two reds side by side, they could hardly be more different, a tall one, and the dwarf one has some flashes of yellow.
13      A promising seedling where the red central zone has become a red flower with yellow tips.
14      Seedling with rose-red center and white tips, good dissected foliage.
15      a block of compact rock-garden sized seedlings.
16      a dwarf one with a different look, truncate maroon red coloring to the eye zone, different.
17      numerous light yellow and white flowered seedlings.
18-19  a couple different white selections
20      looking at these photos, just look at the neighbors... the foliage types, from simple undivided, to sparsely lobed, to deeply lobed, all the way to highly dissected all sit side by side.  What you're not seeing in my photos, is the full breadth of diversity.
One interesting group are the ones with quilled blooms (tubular petals) already represented by the hybrid named 'Jethro Tull'.  Darrell has many such hybrids that are great improvements on the theme.  Shown is a compact quill-flowered type.

[TheOnionMan]

21-22  Photos showing plant size, leaf, and flower diversity, almost any combination is possible.
23-24  Some hybrids do a pretty good imitation of other genera, these look like Marigolds to me
25       variability!  Red, yellow, white, dwarf white with red center lines.
26       variability!  Extra long yellow petals, diffuse red ring.  Tight rotund flower behind it.
27       Enormous golden flowers on a compact plant.
28-30  Darrell is also hybridizing some annual types for possible annual seed clones. There were  some real stunners in here, but I include just a few pics.

Even with 30 photos posted, I don't feel that I've done justice to the wealth of genetic diversity in evidence during my visit to this remarkable field. I hope that in a few years, some of the really diminutive types become selected and named for the rock gardening world, even if they're not of interest to the "perennials industry" wanting more substantially sized plants (Darrell assured me he has flagged some of the "little guys" for his fellow rock gardening friends).

Long live Tickseeds!

[Carlo]

Fabulous stuff Mark. Thanks for bringing Darrell's work to everyone's attention. Let's hope we all get to see some of these for the garden soon!

[Maggi Young]

Very interesting to see this project of Darrell's, McMark.  Cheery flowers, are they not?

[cohan]

interesting view of the project, nice to get the whole routine from start to finish...

[Armin]

Mark,
interesting hybrids. Some of the perennials show gray leaves.
Are those fine hairs or mildew infections?

[mark smyth]

I just love Coreopsis but went off them with current trend of fine foliage and non hardy "hardy" plants. No close ups?

[TheOnionMan]

Armin, there are indeed some hirsute ones, most are glabrous, some have gray foliage but mostly they're green.  Yes, there is mildew on some plants.  The fields on this farm are used for growing annual cut flowers; the rows adjacent to the Coreopsis trials are Zinnia, the Zinnias and many other annuals showing lots of mildew, particularly this year with our record-breaking stretch of heat.  Whether some Coreopsis are showing mildew from that adjacency, I don't know.  One could select for mildew resistance because some plants showed no mildew problems while others showed lots of mildew.  My understanding is all selected Coreopsis are to be trialed in various US States and in EU nations, so I suspect if mildew showed itself a consistent problem with any selections, they will not pass trials.

Mark, there are still nurseries and web sites that claim Zone 4 for cultivars like 'Sweet Dreams', very misleading, others claim Zone 6, and still others claim Zone 8   As mentioned, the problem is that breeders have used an annual species in their breeding program, resulting in plants that are not reliably perennial.  Possibly the plants were not sufficiently trialed, because the majority of feedback I've seen on USA sites show that on some of the newer cultivars, they are of weak constitution and die out.  My own experience growing several newer cultivars several times is, they are not hardy here in Zone 5.

Mark, some closeup for you. A bright yellow one with small red markings (I like this type), an odd open-quilled tube type with the inside red and outside yellow (not my cup of tea, and Lesley... , but these types and many variations open up whole new lines), and the last showing two pale yellow types, one with those "color shifting" flowers that turn reddish in cool weather (again, not my cup of tea as I like solid stable colors, but apparently there is interest in these types).

[Armin]

McMark,
thanks for the detailed reply. I got recently mildew infections on my aster amellus and aquilegia sp..,too. Wet, cold nights and warmer day temperatures seem to support the infestation. I sprayed a rape oil solution - it helps successful when sprayed at the beginning of the infestation.