Question
I'm trying to get a large area of perriwinkle to fill in but I keep getting dandelions coming through. Can I use a weed and feed as though it were grass? Do you recommend a brand? Mike

Answer
Weed-and-feed products contain a herbicide called 2,4-D which is known to be able to control periwinkle, too. Therefore, if you apply weed-and-feed you risk killing the ground cover, also.

For people who wants to eradicate the ground cover, it is normally recommended to mow the product back to the ground and spray new growth with glypsophate because 2,4-D does not give consistent result. This does indicate that you could give 2,4-D (broadleaf weed control products) a try. You will have a greater chance of eradicating the dandelions than the ground cover. This is because growth which is more than one season old tends to develop glossy leaves through which the herbicides do not easily penetrate.

However, there is a risk if you use weed-and-feed. If you use it, use it in fall when new growth has hardened off and when control of dandelions are more effective anyway.

I would probably continue to hand weed dandelions for best control. If you do this both in spring and fall, you should get very good control.