Light is required for seed germination. Seed can survive for up to 10 years in the field, depending on environmental conditions, but it appears that few seeds survive beyond 2-3 years in the Central Valley. Shaded conditions reduce flower production and root growth. In some areas, flowering plants may be found year-round in areas not exposed to severe frost. Yellow starthistle litter appears to inhibit germination of its seeds, probably by blocking light penetration.
Young seedlings are especially resistant to the effects of fall drought.
Where species occur together, seedlings and rosettes of Sicilian starthistle often out-compete those of yellow starthistle . Monitoring and spot eradication of plants when they are discovered can prevent the spread of starthistles. Management techniques, such as grazing, mowing, burning, and cultivation, can prevent seed production and control infestations when employed over a period of 2-3 years or more, depending on the degree of infestation and other factors. These methods must be properly timed to be effective. Mowing too early can result in high seed production.