The first step to having a healthy and attractive lawn and controlling weeds is choosing a grass variety best adapted to your lifestyle and available resources. Factors to consider would be high traffic, shaded and sunny areas, type of soil, available water and amount of time available to care for the lawn.
Irrigate properly to help reduce annual weed infestation. Light frequent irrigation encourages weed seed germination, even if a pre-emergence herbicide has been applied. Water 1- 1.5 inches per watering. Do not water again until you see signs of wilt. Turf will also turn a shade of blue green when it is water stressed. The best time to irrigate your lawn is between 10p.m and 6a.m.
Mowing The preferred mowing height for all species of grass is 2 ½ - 3 inches. The minimum height that any lawn should be mowed is 2 inches. Mowing to heights less than 2 inches results in decreased drought and heat tolerance plus higher incidences of insect, disease, and weed problems. The seeds of some weeds require high light intensity to germinate. The shaded environment near the soil surface in a high mown lawn helps deter weed germination. Mowing frequently enough that no more than one third of the grass height is removed at any single mowing. If the mowing height is two inches the grass should be mowed when it is 3 inches tall. If the mowing height is 3 inches, it should be mowed when it's about 4 inches. Keep your mower blade sharp to avoid shredding and fraying leaf blades. Grass clippings should be allowed to fall back into the yard to provide natural nitrogen in the soil.
Pre-emergence herbicides A Pre-emergent is activated in the top layer of soil where the weed seeds sprout, and by design it stops the plant from growing. A pre-emergent is NOT effective once the weeds are showing. Spreading out the herbicide so that it is evenly distributed is critical. It must also be watered into the soil within the appointed time period. The soil must remain undisturbed in order to maintain the barrier. A pre-emergent has to be replaced, or replenished. Pre-emergence should be applied two to four weeks before the seeds start to germinate in mid March to early April depending on weather. Warm moist springs cause earlier germination. The temperature of the soil ( 55-60 degrees) as it starts to warm up in the spring is going to be the primary indicator of the pending arrival of various weed species. With normal weather patterns pre-emergence herbicides give good to excellent control of crabgrass, foxtail, and barnyard grass. Do not over seed into areas that have recently been treated with pre- emergence.
Post- emergence herbicides Perennial broadleaf weeds can be controlled by post emergent herbicides. It is important to properly identify the weed before choosing an herbicide. Some common perennial broadleaf weeds in lawns are dandelion, field bindweed ( morning glory), White clover, curly dock, ground ivy, Canada thistle, broad leaf plantain, buckhorn plantain and yarrow. The best time to control perennial weeds is in late summer or early fall when weeds are preparing for winter.
Core cultivate ( aerate) the lawn at least once a year to reduce compaction and to control thatch.
Fertilization Fertilizer may be needed if the lawn has poor color and vigor, doesn’t recover from traffic or more weeds are present. Nitrogen is the most important nutrient for lawns. Do not use Phosphorus or Potassium unless soil test indicates it is needed. Cool season grasses should be fertilized in fall, late spring and little in the summer. Warm season grasses should be fertilized late May, June, avoid fertilizing in late summer and fall.