Monday, October 19, 2015

Cultivars vs. Straight Species -- Viburnum Dentatum / Arrowwood Viburnum

So where do you stand on the whole cultivar vs. species issue?

Here at Garden of Aaron, I grow three types of Viburnum dentatum (arrowwood viburnum), which is native throughout much of the Southeast, Midwest and Mid-Atlantic and up into New England.

Here is how the straight species looked in early October:

Here is the form of a Viburnum dentatum (straight species), growing in full sun and awful solid clay 'soil' (1st year in the garden)

Here's a close-up of the foliage, which I'd say still looks pretty darn fresh for early October!

Here is how the 'Pearl Bleu' cultivar looked at the same time:

Here's V. dentatum 'Pearl Bleu' -  as you can see, much of the foliage has folded in half and quite a few leaves have burnt edges.

And here is the 'Chicago Lustre®' cultivar, also on the same day:

By contrast, the foliage on the 'Chicago Lustre' cultivar of V. dentatum looks fresh, lush, healthy and deep green. 

Remember, these are all the same species - just different cultivars - growing in very similar conditions.

In fact, here's a side-by-side shot to show you that 'Pearl Bleu' and 'Chicago Lustre' are growing literally side-by-side. They're both on the northwest side of the house, which gets mostly shade all morning, but bakes in a surprising amount of sun on summer afternoons. In fact, I'd say 'Chicago Lustre' may actually get more of the afternoon sun and perhaps provides a bit of shade to its 'Pearl Bleu' companion.

'Pearl Bleu' on the left, 'Chicago Lustre' on the right. Both shrubs were planted at the same time. Both actually died back to the roots (after I stored them in the garage over the winter and shamefully neglected them), but 'Chicago Lustre' has clearly roared back more vigorously than 'Pearl Bleu'...

Interestngly, the straight species produced more fruit this year than either of the cultivars (although the berries on Chicago Lustre appeared to be larger and more plump than those on the species). All the Viburnum dentatum berries on the species plant and 'Chicago Lustre' have already been devoured by the birds. (I suspect that a mockingbird and a blue jay divided the ones on the species plant.)

I'm planning to add a few more V. dentatum cultivars to the garden this autumn (from Classic Viburnums nursery, which has an amazing selection of the genus), so perhaps I can report back in a year to give a comprehensive overview of the relative strengths of the different cultivars vs. the species.

Oh and then there's this little seedling that popped up on the corner of the house right near where 'Chicago Lustre' and 'Pearl Bleu' could have canoodled. I've transplanted it to someplace where it will have a bit more room to spread its wings...

I'm fairly sure that this is a Viburnum dentatum seedling. It seems to have taken the transplantation well. You'll notice that the foliage is lighter-green and has more of a matte finish, but otherwise seems just as clean and healthy as the 'Chicago Lustre' foliage. 

How about in your garden?

Do you like growing straight wild species plants or do you seek out cultivars?

Personally, in some cases I favor the straight species and in other cases I see the merits of cultivars.

For instance, I chose to grow the 'Miss Huff' cultivar of Lantana camara because it is supposed to have better cold hardiness than the species and I was worried that the straight species would not survive here in Tennessee. (Actually, I'm not sure one can even find a straight species Lantana camara at nurseries. The only ones I've seen for sale are different cultivars.)

With Viburnum dentatum, the jury is still out for me. I'd say that the species has done much better so far than 'Pearl Bleu', but I quite like the 'Chicago Lustre' cultivar.

In other cases - for instance with Echinacea purpurea (purple coneflower) - I only grow the straight species. For one thing, I've read that the species is tougher and has greater longevity than the cultivars.

The cultivars of many flowering plants are bred to have bigger, fancier, 'double' flowers. But if you garden to help the bees and other pollinators like I do, you're probably better off choosing a plant with simpler, single flowers. As says: "Most double flowers are of little use [to bees], as they're too elaborate. Some are bred without male and female parts, while others have so many petals that bees can't get to the nectar and pollen. So single dahlias are popular with many bees, while doubles are usually ignored."

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