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On Gardening: Cobalt verbena super from north to south

Norman Winter, Tribune News Service on

Published in Gardening News

It’s planting season for many and verbenas are high on the list. We had just fallen in love with Superbena Imperial Blue verbena and piled on a bunch of awards then, stop the presses! It has a new name, which is now Superbena Cobalt. Not sure if this would be similar to Shakespeare’s "what’s in a name" scenario, but one thing is for certain: It is even better than The Garden Guy thought.

This year a cold spell of a few nights had The Garden Guy moving containers to the garage. It was about five nights straight. Several of these containers had Superbena Cobalt verbena. There were three other containers of verbenas on the hillside that I did not move. All of them are now in a stage of riotous bloom.

Superbena Cobalt is a crazy blue or violet blue. It is this color that has always driven photographers crazy. Sometimes it looks like its name suggests, the old-fashioned cobalt blue. Then there are times it looks more purple. Even the Proven Winners website has trouble nailing the color. There, it looks purple. But I can’t fault that, because as I write this looking out my sunroom’s windows, I see blooms of cobalt blue and purple and all on the same plant. One of my Facebook followers said it even seems to glow!

This verbena, winner of Top Performer at University of Georgia and University of Florida, had a Perfect Score Award at Michigan State University. In other words, from north to south. And rest assured, at your home too, you will have an award-winning blooming performance bringing in butterflies and hummingbirds.

The vigor will surprise you too! Proven Winners describes it as 6 to 12 inches tall with a spread up to 30 inches. As they mound together in a mixed container, don’t be surprised to see blooms 2 feet high, maybe even taller and some falling 2 feet over the rim.

Superbena Cobalt verbena will need a lot of sun. The soil need not be luxurious but as I always say, fertile and well-drained will be perfect. Tight compacted clay that takes a pickax is hardly suitable. On the other hand, a large mixed container with a good lightweight potting soil will give you the green thumb.

I’ve been trialing verbenas for a long time, including old heirloom varieties, so know this: The handheld pruning shear is the friend of both you and the verbena. Cutting back to remove stressed woody shoots will stimulate new growth and more blooms and add years to your planting if you are in the right zones.


I largely grow mine in mixed containers. This year the Superbena Cobalt blue blooms have coincided with an uncountable number of yellow flowers from Lemon Coral sedum. I’ve got partnerships with both Superbells Pomegranate Punch and Tangerine Punch calibrachoas, as well as Supertunia Mini Vista Scarlet petunia.

Since I am growing them in mixed containers that get watered most every day, I feed every 2 to 3 weeks with a water-soluble mix. Those in the ground can be fed with controlled release granules at planting with additional side dress applications about every 6 to 8 weeks. They are perennial in zones 8 and warmer but considered outstanding value if grown as an annual. Look for the award-winning Superbena Cobalt as you shop during planting season.


(Norman Winter, horticulturist, garden speaker and author of “Tough-as-Nails Flowers for the South” and “Captivating Combinations: Color and Style in the Garden.” Follow him on Facebook @NormanWinterTheGardenGuy.)

(NOTE TO EDITORS: Norman Winter receives complimentary plants to review from the companies he covers.)

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