Flowering period is from June to September.
Russian knapweed is a woody perennial that can form dense colonies.
The entire plant is more or less white woolly when young. It infests alfalfa and grain fields, irrigation ditches and waste areas. It spreads by seed and rootstock and can produce up to 27 rootshoots a year. It emits a substance that inhibits the growth of other plants around it. The leaves are bitter and unpalatable to livestock.