Can you fertilize or spray for weeds more than once?

Absolutely can re spray for weeds if needed, usually after 2 weeks or a month. In fact, that is the norm. Kick it while it’s down. Often it will tell you this on the herbicide label. Particularly older, more mature weeds may need more than a single application, They are not as sensitive to herbicides as young weeds. But when temps hit the 90s, many, but not all, herbicides can damage your lawn grass. Always thoroughly read the label on the chemical you are using.

I used a weed and feed in the front and then in the back sprayed for weeds only (would have to go in the garage and look) and then did a fertilizer 10 days later. Was doing a test to see what worked best in my yard.

Grass type? Fert numbers n-p-k? What herbicide?

Yes

I don’t doubt big companies push their products. But is 32% N wrong for centipede? I think not if used in the right amount.

University based recommendation for centipede lawns in Southern states is 0.5 lbs N/1000 sq ft per application not to exceed 1 lb of N/1000 sq ft per year, and a single 0.5 lbs N application1000 sq ft is often enough.

If the lawn fertilizer was 32% N one would apply 1.56 lbs/1000 sq ft of lawn (50 divided 32 = 1.56).to achieve 0.5 lb N/1000 sq ft

I use 24-2-11 on my centipede lawn, thus to apply the recommended 0.5 lb N/1000 sq ft I apply 2.08 lbs of 24% N /1000 sq ft (50 divided by 24 = 2.08), and yes I round the amount down to 2 lbs.

Another common centipede lawn fertilizer was/is Fertilome 15-0-15 for centipede. With 15% N, one would apply 3.33 lbs of 15% N per 1000 sq ft to the lawn (50 divided by 15 = 3.33 lbs).to achieve the recommended 0.5 lb/1000 sq ft.

So 3 different lawn fertilizers with varying amounts of N, all applied in different amounts, but with each providing the recommended 0.5 lbs of N/1000 sq ft for a centipede lawn.

It is recommended that a centipede lawn fertilizer have a low or 0 amount of P, which virtually all lawn ferllizers do b/c the P easily chemically binds with iron (Fe) making iron less available to the centipede, and iron is an important micronutrient for centipede. Iron, when not bound with P also oxidizes forming acidic condition that centipede favors.

Lastly, the form of nitrogen in a centipede fertilizer should be dominated by ammonical-nitrogen and urea, with little to no nitrate nitrogen.. Ammonical nitrogen is a quick release, acid forming source of N, and urea, usually coated with sulfur is a slow release acid forming source of N. Centipede grows best in acidic soils and acidic forms of N help with this as does the elemental sulfur (also an acidic forming chemical). All this information is on the fertilizer label on the bag.

The label on the bag of fertilizer should reflect proper application rates for centipede in southern lawns and if they don’t then you are correct, they are not providing the consumer the information they need to properly fertilize centipede.

This is important b/c recommended application rates for St Aug or Bermuda are double (1 lb N/1000 sq ft) that of centipede, and a consumer should not be using fertilization rates recommended for St Aug or Bermuda on Centipede.

I never suggest respraying for weeds without knowing much about the issue. To say that you can absolutely respray for weeds if needed would not be my suggestion. He might not be spraying the right chemical for the weed type. If the weed is mature then mowing it will increase the effectiveness of the herbicide. Over spraying a weed, especially a salt based herbicide, we kill the top faster than the weed can transport the herbicide to the roots. The top will die, the roots will still be alive and put up new growth. Over application of a herbicide can be detrimental to the centipede.

32% nitrogen can very easily be over applied. It doesn't leave a whole lot of room for error. The 24-2-11 and 15-0-15 you mentioned would be a lot better. I use 16-0-8 on centipede.

OK Ronk, I agree with your comments here. I was proviided a generalized answer to a general question in which the OP didn’t provide much in the way in details. He since has. And of course the weeds should ID’d, what and how much he used prior to considering a second application of herbicide must be considered, etc.

I agree with your comments on the 32% N - the higher the %N the lower amount of fertilizer will be applied to achieve the 0.5 bs N/1000 sq ft for centipede and for the inexperienced I can see where they might tend to over apply. Less chance of overapplying when using a lower N fertilizer for Centipede.

I happen to be at my fathers house out of town I just noticed a bag of Scott’s weed and feed. I read the label and you are right - they recommend the same rate of application for centipede as St Aug, (1 lb N/1000 sq ft) and this is wrong. If my father used this on centipede (he has St Aug) the rate would be double the 0.5 lb N/1000 sq ft that is recommended by turf and lawn extension specialist through the South.

Anyway I hope we’re good, and I apologize if I was a little harsh in response to your initial comment.