By ground temperature – Once you have determined when to apply pre-emergents, you must also consider the ground temperature. For instance: To prevent summer weeds, apply a pre-emergence herbicide 48 hours after the soil temperature reaches 55 degrees Fahrenheit.
When is the optimal timing to apply pre-emergence herbicide?
Which Month Should Pre-Emergent Weed Killer Be Applied? – The optimal time to apply pre-emergent herbicide varies by area. In northern regions of the United States and much of Canada, spring pre-emergent application may not be possible until as late as May.
How long does pre-emergent pesticide kill weeds?
When to Apply Pre-Emergent Herbicide – For best pre-emergent herbicide efficacy, apply spring pre-emergents after soil temperatures have held at 55 degrees Fahrenheit (12 degrees Celsius) for two to three days. Apply autumn pre-emergents when soil temperatures have been below 70 degrees Fahrenheit (21 degrees Celsius) for two to three days.
Application of Pre-Emergent Weed Control – Early spring and late autumn are the most effective periods to apply pre-emergent herbicides to the ground. The bulk of weeds germinate at this time. However, you may employ pre-emergence weed management throughout the year to combat re-emerging weed species.