Monday, September 23, 2013

Groundcover Review: Cranesbill Geraniums

Geranium Rozanne in early July

Cranesbill Geraniums


- Very floriferous. Lotsa flowers (even in partial shade) + Long bloom season = Quite an impression

- Beautiful foliage

- Does not seem to be bothered by any pests or diseases

- Don't recall seeing hardy geraniums on many lists of drought-tolerant or heat-tolerant plants, but Rozanne survived the brutal heat and drought of 2012 (with supplemental water in full sun) and I have to think they'll be fairly tolerant of both drought and heat in a spot with afternoon shade.


- Not a con necessarily, but just be aware that foliage may scorch in hot climates in full sun. At least that is what happened with Rozanne in 2011 and 2012. She's much happier now in partial shade as you can see from the blooms.

- Rozanne is herbaceous. That means the whole plant dies back in winter, which can leave quite a hole in the garden seeing as Rozanne is a sprawler. Not sure yet if my two other hardy geraniums - G. cantabrigiense 'Biokovo' and G. sanguineum 'New Hampshire' - will perform the same or if they'll be evergreen or semi-evergreen. I can say that so far both are much tighter in their growth habit.

- Can't see much in the way of pollinator action from bees, wasps or hoverflies. There are some little insects that buzz around the flowers, but they don't seem to land much. I think they may just be in the vicinity while visiting the Sweet Alyssum. Or maybe they visit at night when I'm not looking?

- Not native to the U.S.

Geranium sanguineum "New Hampshire" in early July


- Rozanne was my first hardy geranium love and probably still the one I like best. I'd like them all a lot better if the bees seemed more interested. The herbaceous nature of Rozanne is a real drag and can be a challenge in figuring out garden design. I'll have to reserve final judgment on cantabrigiense and sanguineum until seeing how they perform this winter. I think all of these make nice low-growing perennials, but I'm not sure they really qualify as groundcovers. (Although other varieties I don't have in my garden yet, such as G. macrorrhizum are actually supposed to have more of a groundcover habit.)

UPDATE 4/17 - 'Rozanne' ended up being a lovely, but somewhat short-lived plant in my garden. Geranium x cantabrigiense 'Biokovo' has turned out to be one of my favorite perennials. Sure, it might be a bit happier with some more shade (mine are mostly planted where they get full sun all morning and into early afternoon), but it hangs tough during the summer and makes an excellent, beautiful evergreen groundcover especially in spring, summer and autumn. Sometimes 'Biokovo' flowers even attract bumblebees! BUT...I do wish to retract my recommendation on G. sanguineum. This plant has turned into a bit of a nightmare. I thought it was spreading too aggressively and overwhelming other nearby plants, so I decided to rip it out. Ha. Geranium sanguineum - or bloody cranesbill - has deep, thick, red roots. They hang on touch and snap easily (at least in heavy clay soil). And the plant regrows from even small root fragments. The upshot - I've dug up certain areas oh, half-a-dozen times trying to get rid of G. sanguineum and probably will be digging all this year trying to eradicate the last remnants. Meanwhile, I've got quite a few holes and blank spaces in my garden where I can't plant anything lest I need to excavate again in a search for G. sanguineum root pieces. Ugh. Don't plant it. (Unless you're in its native range - Europe, far western parts of Asia. In that case, I guess you could plant it if you wanted a really tough, aggressive native romping through your garden.)