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.