Re: [IGSROBIN] Tuberous Rooted Geraniums
Re: Michael's remarks on the tuberous geraniums: one of the most
interesting side effects of growing hardy geraniums, particularly in my
mild climate (USDA Zone 9b), but selling them in a wide range of
climates, is that I have to make assumptions on cold and heat
hardiness. My customers advise me with letters and suggestions, and I
tend naturally to be conservative, so with much help, we try to get the
right plant in the right place. But hardy geraniums are amazing plants.
Very often there is no indication from their native habitat how they
will do somewhere else. The best example is Geranium sanguineum, which
will tolerate humidity in Florida and Hawaii, grows superbly in the dry
high heat (several months with 90-100+ F days) of the Central Valley of
California, or in the cool moist summers of the Pacific Northwest.
The tuberous rooted geraniums, G. tuberosum, G. malviflorum, G.
macrostylum, G. libani, and others, have not been grown in a wide
enough variety of locales for us to say definitely what they will
tolerate. They do not seem to need winter cold. They will tolerate
summer dormancy, but you can also leave them in the ground and give them
some summer water. In my climate I do not see them reseeding, but we
propagate them from tubers anyway (it is so easy, that there is no need
to bother with seed). Common sense says they will not be hardy where the
ground freezes, but is that actually true? I have no idea. We
recommend them for USDA Zones 7 and above, but that is only because we
haven't heard from anyone growing them outside, in the ground, in colder
Perhaps someone can give us more information.