I have come upon these two weeds in my garden and am wondering if you could tell me what they are. I have attached the first plant’s photo in this message, and will attach the other in another email since the webpage only allows me to attach one photo per message. Hope to hear back from you.
Thank you for contacting Toronto Master Gardeners..
The weed in your picture is a rough cinquefoil or Potentilla norvegica L. It is a member of the rose family and is native to North America. It is prevalent in Ontario, mostly in open areas such as fields, pastures and road sides but will also show up in open, sandy, dry locations in a garden. Depending on its location, it will act like an annual and die in the fall or act as a tender perennial and return in the spring if it survives the winter.
This weed will have small, 5 petaled yellow flowers then go to seed in June and July. It reproduces by seed with each plant producing up to 13,000 seeds.
The best control method for this weed it to remove it before it goes to seed. Mowing can take a flowering top off but the plant will then grow back but be shorter and may cause spreading roots. Pulling out the whole plant before flowering or at least before seeds spread will result in less work in the future.
Here are two sites which have further information :