I have just treated my lawn with feed,weed, and moss killer ?

Question

in some areas the grass looks to be dying when can i treat affected area

Answer 1

A powerful combination if you've used all 3 together! The weed killer will often turn the grass yellow (looks like hay). The moss killer will turn the moss black. You need to use a rake or similar to pull out the dead moss (it can take upto 6 weeks to completely die). Best thing to do, is to wait till the weed/moss dies, remove the dead material. This whole process usually takes about 6-8 weeks. Then you will be left with lots of bare patches in the lawn - you can then start planting new grass seeds in these areas to build up the grass. I would use the lawn feed once the new grass starts going - if there's weed and moss, there's no point in using lawn feed in these areas as there's probably not much actual lawn left until you remove the moss/weed.  

Answer 2

Remember that there is a reason why the moss is growing and not the grass. This is often because the soil is not well drained. I would "scarify" the lawn using a lawn rake or a mechanical scarifier to open up the soil structure before doing anything else.

The weed and feed should mean that there is sufficient food for the grass to grow. I am not sure why the grass itself is dying, as the weedkiller is selective for broadleaf weeds and should not affect the grass. Has it been dry? Have you watered the lawn recently? The treatment may have put the lawn under stress and it is normally recommended to do this type of work in spring, not mid-summer, but hey! Needs must sometimes.

For such a small area, I would think about using turf not grass seed, as the results are much more reliable for the amateur.