Which phlox is best for you?

Hello Everyone,

Last summer I did the wrong thing. I bought a plant on impulse, in spite of what I knew would happen. But there they were, in spectacular bloom at the nursery, just LOADED with swallowtail butterflies!

I was, after all, shopping for plants for a butterfly mini-meadow. What stronger sales pitch could there be? I stood still for a moment and asked myself to imagine these beautiful plants the way I knew they would look, if not by the end of this season, perhaps early the next…leaves sagging under a heavy coating of white powdery mildew.

But even that didn’t work…the butterflies won. I ended up finding room on my crowded cart for five more plants--some of the most beautiful phlox paniculata I’d ever seen.

I planted the mini-meadow within a few days, and the phlox did not disappoint. For the next several weeks they continued to look amazing, and I saw an impressive number of butterflies on those phlox. And, surprisingly… no mildew! (Not yet, but probably next year, I thought).

Well, it turns out they may not have been as big a mistake as I thought at the time. Because the Mt Cuba Phlox Trial Results have just come out, and that particular variety of phlox—‘Jeana’—actually did quite well.

Phlox paniculata ‘Jeana’ not only managed to remain completely disease free in trial gardens that were chock full of powdery mildew by the end of three years of phlox trials (talk about a tough test!), but also attracted many more butterflies with her abundant, delicate, rosy-pink blooms. ‘Jeana’ brought in an average of 539 butterfly visits per plant, while her nearest competitor, ‘Lavelle’ had only 117 visits per plant. (Data was collected over two years' time).

The results of the butterfly count were enough to attract the attention of University of Delaware grad student, Keith Nevison, who measured the quantity of nectar and concentration of sugar in the nectar of ‘Jeana’ and other phlox, attempting to find out what the butterflies were so excited about. But he found that ‘Jeana’ is not making more or better nectar. It had to be something else. 

Nevison’s current theory—yet to be proven—is that the smaller flower size of ‘Jeana’ and particularly the narrower and shallower flower tubes, make for a preferable nectar harvest environment—allowing the butterfly to quickly slurp more nectar without moving as frequently. Fascinating, isn't it?

The phlox varieties were evaluated based on mildew resistance, length and quality of bloom, visitor ratings, neatness of foliage, and popularity with pollinators.

You might want to read the report, there’s a lot of great stuff in there. But if you want just a little more, here are some takeaway points:

  (Table here--see subscriber version, for some reason it didn't come through for the archives!)

Looking ahead to this fall: Adkins Arboretum is talking to Co-design Graduates about gardens to put on the Native Garden Tour for early October. If your garden is chosen, you can order all your native plants from the Arboretum at a generous 35% off. So this is a GREAT way to finally finish installing your garden! (If you are interested or even just curious about the details, please send me an email!)

Chris Pax

Christina Pax