Thus, no pollination is necessary and all seeds produced are genetically identical to the parent plant. The development of seed occurs before flowering. The apomictic nature of jubatagrass is probably the most important characteristic responsible for its weediness as well as its limited range. An individual inflorescence or plume can produce 100,000 seeds and large clumps can make a million or more seeds. Flowering generally occurs from late July to September, often in the first year of growth.
Some plants can flower twice during the same season.
The tiny seeds are spread up to 20 miles from the mother plant by wind. Seedlings usually become established in spring and require sandy soils, ample moisture and light. Like jubatagrass, seedling survival is low in shaded areas or in competition with grasses or sedges. Unlike jubatagrass, pampasgrass can tolerate winter frost, warmer summer temperatures, more intense sunlight, and moderate drought. This accounts for its success as an ornamental in the hotter and drier inland areas of California.