Although it is generally preferable to fertilize home lawns in the fall, a late May fertilizer application can help the turf retain its color and vigor during the summer. If conservative nitrogen rates are used, fertilizer can be applied in late spring without dramatically increasing vertical growth. To aid the turf in keeping its color longer, select fertilizers that contain slow-release nitrogen sources. These will be listed on the fertilizer bag as sulfur- or polymer-coated urea, urea formaldehyde, methylenediurea, dimethylenetriurea or natural organic/biosolids. Apply 0.75 to 1.0 lbs. N/1000 sq. ft. with a product that contains 50% or more slow release fertilizer. If possible, try to schedule a fertilizer application prior to a soaking rain. If not, irrigate after application to wash fertilizer off the leaf blades and into the soil so the nutrients are absorbed by the roots. A properly fertilized turf has fewer weeds, is more resistant to insects and disease, and decreases water runoff compared to malnourished turf.