Where winters are cooler, zonal geranium, Pelargonium X hortorum, performs as a warm season annual. It is perennial only with shelter from frost. Locally, traditional cultivars are so reliably perennial that they can get congested without thorough pruning and grooming after winter. Frost occasionally ruins outer growth, but rarely kills entire plants with roots.
Modern cultivars bloom more profusely and more colorfully than old cultivars, but are not quite as resilient. They are more likely to rot during the damp and cool weather of winter. They bloom exquisitely from spring through autumn though, with bright hues of red, pink, peach, salmon and white. They stay lower and more compact, so require less grooming.
The more popular modern zonal geraniums should not get much more than two feet high and wide. Their small flowers bloom on globular floral trusses that can get as wide as six inches. Traditional zonal geraniums get bigger, with smaller floral trusses. Nearly circular and aromatic leaves generally exhibit darker halos between lighter centers and margins.
Tony Tomeo 
I grow loads of these each summer and occasionally take cuttings for next year or keep the plants indoors over winter. 😃
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Yes, they are perennial in that manner. Ours live outside throughout the year, but should get cut back as they start to grow at the end of winter. Otherwise, they get shabby and overgrown. As they get old and decrepit, I plug new cuttings in with them to replace them as they rot out.
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Pelargoniums are grown outside here, and also as kitchen window plants. I almost always have one of the paler ones inside. They are amazingly resilient. If I am away for a long time, and they won’t be watered, I shake off the soil and hang them upside down in the shed. You can also just leave them in the pot, although they’ll drop all their leaves. They are easy to bring back to life, although it does sound like plant cruelty. Perhaps you could write a horridculture post about it, teaching me to do better!
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I doubt that there is better. Mine are brutalized even more. I cut them back at the end of every winter, and if I need more, I just plug bits of the old stems where I want new copies. I wrote about using them as a cover crop a while back.
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