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 10 pm and 6 am.
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 high mown lawn helps deter weed germination. Mow frequent 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.
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 when seeds 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, will 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.
Fertilizer may be needed if lawn has poor color and vigor, doesn’t recover from traffic or has more weeds present. Nitrogen is the most important nutrient for lawns. Do not use Phosphorus or Potassium unless a 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 late summer and fall.
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