When Do You Weed or Seed in Florida?

Striking Them Down First

• Many annual weeds use the warming spring and summer to germinate and reproduce in your turfgrass, especially stressed locations. Poor turf maintenance and heavy shade contribute to thinning grass where weeds grow quickly and spread profusely. To control spring weeds before they emerge, apply a preemergent herbicide. This chemical prevents weed seed germination and eventual establishment. In general, according to the University of Florida, South Florida lawns needs a preemergent by February 1 and in Central Florida by February 15, while North Florida can wait until March 1. Florida is also prone to winter annual weeds. To control them, the University of Florida advises applying preemergent herbicides when nighttime temperatures have dropped to 55 to 60 degrees Fahrenheit over a number of days, usually in early October in the northern portion of the state and late October to early November for central and southern parts of the state.

Controlling Those Surprise Weeds

• Apply post-emergent herbicides by May for most Florida's regions to remove broadleaf weeds. These herbicides target weeds specifically and do not harm the surrounding grass. To avoid damaging nearby plants, however, select a calm, windless day with mild temperatures between 60 and 85 degrees F for application. Your herbicide quickly permeates the targeted weeds without overspray onto desired plants. If you have true grass weeds within your turf, carefully pull them out. Applying a grass-specific post-emergent herbicide to these weeds damages nearby turf.

Seeding for Green Perfection

• Outside of South Florida, where lawns usually don't go dormant, warm-season grasses enter dormancy in the fall and winter, creating a stark brown appearance in your yard. Each year, overseed with a cool-season species -- the University of Florida recommends ryegrass -- because their active growing period stretches between fall and spring. In general, overseed your Florida lawn between November 15 and December 15. Cool-season grasses germinate rapidly when air temperatures are lower than 75 degrees F. If you overseed in the early fall, however, cool-season species do not respond to the warm soil and remain dormant until cooler weather sets in.

Scheduling Weed and Seed Successfully

• Do not apply herbicides within two to four months of seeding your turf. Both preemergent and post-emergent chemicals affect your germination success, causing widespread failure. For example, overseed normally in fall, but do not apply any winter herbicides. Simply wait until February or March to apply spring preemergent herbicides. Your newly seeded grass should be a minimum of 2 inches tall before any herbicide application. Tall grass indicates healthy establishment, allowing the turf to withstand herbicide chemicals without damage.