Both G. macrorrhizum and it's off-spring, G. Ã cantabrigiense are great plants for what I call "dry shade".

As for 'Rozanne', up here, it's a perfect plant in a dry, full sun area. I describe our summers as "hot and humid" although I understand that's relative. In any case, I am certain it will do well where you describe.

Regarding sources that quantify the amount of water given to be called "drought tolerant", I've never seen any, and I've been working in the industry for over 12 years. I think most descriptions are simply based on relative experience and/or observations. For a good general source on perennials, consider Armitage's book (third edition just released).

What might be drought tolerant in zone 4,5, or 6 with rain, may not be drought tolerant in a very hot, dry climate.

I have grown the ivy geraniums for many years and I can tell you that, like most geraniums it does like to dry between waterings, but no more than a zonal geranium. I don't think it would do well in a true xeriscape garden. If however you do plan to give it a bit of shade in the heat of the day and water occasionally it might be ok

If you look at where a great many geranium species grow natively - in areas surrounding the Mediterranean, in open meadows, rocky outcroppings or stony screes - it should be apparent that these are quite likely to be rather drought tolerant, subsisting on only natural rainfall in what tends to be dry, often arid areas. There are some exceptions of course but on the whole, most hardy geraniums are rather drought tolerant once established. They often don't mind supplemental irrigation but most do not require much of it.

The Gardeners Guide to Growing Hardy Geraniums is an excellent monograph on this genus that discusses cultural needs in some detail. A few the authors note as being particularly well-adapted to hot, dry sunny locations are G. endressii, x riversleaianum, maderense, cinerium, sanguineum and tuberosum. And quite a few more species and hybrids will tolerate quite dry conditions if provided at least partial shade. These include macrorrhizum, nodosom, x oxonianum and x catabrigiense.

Ivy leaf geraniums are pelargoniums and do require a bit different growing conditions. And as most in commerce are very highly hybridized, specific qualities like drought tolerance are a bit of a toss up. For best performance on these, I'd recommend routine irrigation.

For long bloom and drought tolerance, I would recommend one of the sanguineum hybrids or selections. Nodosum is equally drought tolerant, but the bloom is rather "spotty". Also, Nodosum tends to self-seed a lot, giving a cotttage garden or informal look. I find that cantabrigiense and macrorrhizum are definitely ground cover types, with a limited bloom period. They are very drought tolerant and require minimal care, but can get a little boring.

Hi Luxrosa, I know you from the Antique Rose Forum. I have 3 Roxanne geraniums in my Livermore garden in part sun. They get sun until about 2-3pm. I have them on the drip system so they get watered every 3rd day when the roses do, but they hold up and do bloom from summer to first real freeze (early Dec for me). It's a wonderful plant. I'm using some this year to plant near my yellow Austin's where the roses will shade them later in the day.

As you know, I get well over 100% some summer days and are consistently over 80 from July through early Sept. If I remember right, you're in Emeryville. I think they would love it there. They are sensitive to drainage in our clay soil so amend well for that.

They're just wonderful. Such a pretty color and the delicate looking leaves are pretty too. The plant sprawls later in the year covering about 2+ feet total, so it will cover some ground.

Debbie

hello Lux, why not try some of the Canary Island geraniums - palmatum and maderense. Also sanguineums, endressii, psilostemon (Sp? fabulous colour) and, imo, renardii - the most gorgeous foliage. some of the rather lovely alpine hybrids such as ballerina, Laurence Flatman and the veined versicolour might be good for you. Peter Yeo from Cambridge Botanic Gardens wrote an extremely good monograph on hardy geraniums - worth looking out for.

I have loads of G. machrorhizom (big root geranium) in Iowa -- I've never watered them (but then we've been in the flood zone the past three years) I gave some plants to my son in Denver three years ago & they're still alive -- so that means they pass the test for draught and absolute neglect. In Iowa they are so vigorous and spreading. In Denver, very contained.

I have loads of geraniums, but I have never had Rozanne overwinter (nor has my daughter), so I'm rather skeptical of that plant & they cost too much for annuals.
Good luck
Susan