Depending on your location and Plant Board specification on fertilization use.
Spring time is a great way to introduce spring green up. But, the limitation are as Indylawn suggested on slow release nitro effect, is non exsistant. Its effect will give quick responses to turf green up. Special curcumstants can warrent the use of Liquid fertilizer where granular fertilization requirement are very low Example would be 1 to 2 apps. per year of fertilization to fescue. We will use Iron treatment in subsitution of niro ferts during the heat of summer. But, use urea in the spring. Just watch out for white surfaces like concrete walks, driveways and picket fences when using iron treatments.
Although not visible at the time of application, The iron will oxidize and turn a rust color and stain anything white or light colored. Then you will spend some time trying to remove it. It can be done though with the product called: C L R.
