Many beautiful wildflowers can be added to your flowerbeds or as a natural border to your property. Many flowers were considered weeds at one time but are now prized for their blue colour and their ability to attract pollinators and butterflies to a garden. A few blue-flowering weeds should be removed or destroyed with a weed killer to stop their spread.
Corn speedwell or Veronica arvensis is a lush broadleaved annual weed that produces small blue flowers. Flowerbeds that have not been heavily mulched or areas of poor soil where there is little competition may invite the spread of this weed.
Wild violets are a perennial weed with a strong root system that is difficult to remove. This common blue-blooming weed grows well in shady areas where grass may have more difficulty becoming established. They are also found in purple, grey and white.
Blueweed or Echium vulgare L. is a common plant found in pastures and natural habitats. The pyrrolizidine alkaloid found in this plant can be toxic to horses and cattle, according to Montana State University.
Blue vervain, also known as wild hyssop or ironweed, is more common east of the Mississippi. According to Ohio State Extension, blue vervain was used to dress the wounds of Jesus Christ.