Although chemical control is a very important part a good weed control and fertilization program, cultural controls are just as important. Proper mowing and irrigation will ensure that the chemical controls and fertilizers applied are best able to achieve their desired result.
Whether you mow yourself or use a contractor to maintain your lawn, frequency, height, and sharpness of blades are all very important. If you mow less frequently, which we will say is less than every two weeks, you allow seed heads to develop on many grassy weeds like crabgrass, bahia, and nutsedge. Although preemergent herbicides prevent many seeds from developing in to plants, after several months the preemergent becomes less effective and later in the season seeds can begin to germinate and create new plants. Maintaining your lawn at the proper frequency will reduce the number of seeds, and their potential to germinate in to your lawn.
Watering is another very important aspect of a proper lawn management program. Proper irrigation ensures your lawn is able to utilize the fertilization properly, helps it grow to outcompete unwanted weeds for space, and makes your lawn inhospitable to certain weeds like nutsedge by reducing the amount of water that sits on your lawn over extended periods. We recommend deep watering, roughly 30-40 minutes per zone two times per week for established lawns. This will have to be altered for newly sodded or seeded lawns but once established this watering schedule helps the development of deep root growth, prevents desirable conditions for weeds like nutsedge, reduces the chance of fungal disease in your lawn, and helps your lawn outcompete weeds for space.
Finally, using dull blades on your lawn mower rips the blades versus cutting them increasing the chance of disease and makes the plant utilize energy in recovering instead of outcompeting weeds for space. We recommend you sharpen your blades at least once per season depending on the frequency at which you cut your lawn. Sharpening blades is fairly simple so sharpening them at the beginning of the season and mid-season will ensure even those that mow weekly will always be using appropriately sharpened blades on their lawn.
Without the inclusion of these practices, achieving the desired results may be possible, but it is much less likely, and will take a much longer period of time.