抄録
In the investigation of the principal Pelargonium producing lands of the world it was found that the characteristics of such lands were of yearly average atmospheric temperature ranging from 16 to 18 deg. C. with yearly average rainfall of approximately 1, 000 m.m. and no frost during winter. The Seto Inland Sea district of Japan which is the principal Pelargonium producing land fairly satisfies the conditions of yearly average atmospheric temperature as well as the amount of yearly rainfall, but its monthly average temperature goes down as low as 6 deg. C. with frequent frost during the coldest days of winter. Investigations were conducted on the topography and the wintering of the plant in a small island of the Seto Inland Sea and it was found that frost damages on the Pelargonium had been much influenced by cold air currents. Consequently it was discovered that prospective farms should be chosen so avoidable of cold air current passage as much as possible for the plant. The result of the investigation of the relation between the topography of the farm and the number of the plant withered by frost showed that for the successful wintering of the plant the frequency of frost should not exceed 16 to 20 during the winter season.
