Most shrub roses are, at least initially, the product of various crosses between Species Roses and modern Bush Roses , breeded during the 20th century. The result is a wide mixture of shrubs of varying sizes and colours although they are usually quite large, reaching 5 or 6 ft in height.
Most shrub roses are tough and reliable. Many of them can be relied upon to repeating flowering, given good conditions, bringing colour when most other shrubs have ceased to flower. Their growth is generally graceful and shrub-like. The flowers often have no very definite form, gaining much of their beauty from their massed effect.