Blueweed is a perennial flowering herb that grows and spreads via rhizome. It is naturalized in many parts of the country and can tolerate poor soils that are salty or alkaline and where other plants could not live. Blueweed blooms from June through November. It is not widely cultivated as an ornamental and is considered an invasive weed in many regions that can compete with and threaten cultivated crops.
Water your cultivated blueweed deeply in the fall to prepare both the soil and the plant roots for winter drought conditions. Step up watering in the fall before the first hard frost, and taper off irrigation after the first hard frost. Supplement rainfall by occasional irrigation if needed to keep the soil from completely drying out.
Protect your blueweed plants from winter frosts and cold drying winds by mulching around the base of the plant. Use several inches of organic mulch material, such as shredded bark or cocoa bean hulls to act as insulation.
Cut back and mulch over the crown of your blueweed plants in climates where the top foliage does not overwinter. Use clean sharp secateurs, and shear down to the crown of the plant. Lay the mulch over the crown in a blanket at least two inches thick.