My once weed free lawn now has weeds. How do I get rid of them?

Question

I used Scott's Weed & Feed about 3 weeks ago but the weeds are still thriving. Can I use it again without damaging the grass which is St. Augustine?

Answer 1

St Augustine grass is different. The Weed & Feed available in most of the US is not for St Augustine! St Augustine does not take well to 2,4-D, which is a major ingredient in Weed & Feed. If your bag allows your product for St Aug, then it is a locally available formulation for St Aug and you are safe. Be sure to read the bag!
I reckon you are probably lucky the temperatures were too low for the Weed & Feed to work, because if it had, your good turf might have been damaged/killed as well.
St Aug needs a weed control call Atrazine. It has both pre-emergent qualities (i.e. kills weeds as they germinate, like weed-abortion) and post-emergent qualities (kills existing weeds.) It will work in the milder temps of Nov-Mar and is in fact illegal when the temps rise above about 85 degrees. That is the weed killer you need to apply. Now.
A couple of other helpful hints:
The better the turf is fertilized, the better it beats out the weeds.
Overwatered St Augustine is always weedy. Cut back on watering. An hour (rotary heads or sprinklers) or 10 minutes (non-moving heads or sprinklers) 2x, and definitely no more than 3x a week, is plenty.
Check for little grey insects running around in the grass when you pull the blades back like you were searching a scalp for lice. You may have chinch bugs killing the St Augustine and leaving welcoming dirt for weed seeds to grow in. If you have some, treat with a granular insecticide.

Answer 2

They do keep coming back no matter what you use, especially if you have neighbors who don't cut their grass - please see my story!
Personally I am a chemical-free type, and it means my lawn isn't perfect any longer, although it once was... I have a neighbor who has stopped cutting her grass except for once at the end of summer and it has completely infested my once perfect lawn with her weed seeds... my lawn is full of them. I now take a different approach - the weeds are green, like the grass, they aren't prickly or poisonous, so I have given up the fight and stopped worrying about it. Where I can't have them (like in the sidewalk cracks) I spray them with straight vinegar and they are dead in 2 days. If you don't care so much about using chemicals (which kills good bugs like ladybugs which keep your flowers from being eaten alive, for example), try a lawn service coming to spray for a few months until it's under control, then apply the Scotts to maintain it.

Answer 3

weeds usually are an indicator of something wrong with the quality of your soil. different weeds indicate different things. Like dandelions mean a lack of calcium. First find out what type of weeds you have and then correct the problem organically. I suggest getting an organic weed encyclopedia. Usually the solutions are listed also.

Answer 4

Identify the weed then find that weed specific herbicide and spray the yard. In the fall core aereate the yard and seed the yard heavily with seed which will grow and help to smother out the weeds.