[header] How to apply weed and feed [title] Plan to apply it in the spring and fall. [step] Weed and feed works best when applied when weeds are actively growing and the daytime temperatures are between 60 ° and 90 ° f (15. 5 ° and 32.2 ° c). In most areas, this means applying once during the spring, and once during the fall. 
[title] Mow your lawn 2-4 days before you apply. [step] If you can, mow your lawn to a medium height 2-4 days before you plan to apply weed and feed.