What is the Best Time to Spray Weed Killer?

If you're struggling with weeds in your garden, you might wonder when to spray the weed killer. Manual labor, such as tilling and fertilizing, can help control weeds. But for some gardeners, spraying weed killer is the more efficient way to eliminate weeds.

When it comes to weeds, timing is everything. So if you're spraying your garden with herbicide, give the weeds a fighting chance by spraying them when they're young and vulnerable. Plan ahead by purchasing the right kind of herbicide and following the manufacturer's instructions.

Herbicides can kill pesky weeds. Spraying them at the right time maximizes their effectiveness, but it depends on the herbicide you are using. Much of this depends on whether or not you attend the lectures at your local community college extension office.

Before You Spray

We might not want to know how weed killers work, but we should. Spraying chemicals on weeds is like spraying a tanning lotion on one’s face. Herbicides affect protein production and root formation by blocking the growth of weeds. We must take care when we spray weed killer, though; herbicides are less toxic than pesticides.

Pre Emergent Herbicide

Lawn lovers can employ the power of pre-emergence herbicides in their arsenal, arming themselves against annual weed problems like crabgrass. An all-natural weapon, this herbicide goes after seeds, not roots, and is effective in keeping crabgrass from germinating weed seeds each spring.

Early spring is the best time for weed killing because no one wants to have crabgrass in their lawn. Hence, don't be a "weed" at home when trying to get rid of weeds.

Apply weed killers in the early spring, and then again around eight weeks after the first application. This is especially helpful if your yard is covered with crabgrass.

Post Emergent Herbicide

For best results when using post-emergence herbicides such as glyphosate chemicals, spray weeds before they get too old.

One way to win the war on woody shrubs is to chop down the offending plants and wait for the battleground to get a new crop of greenery.

Or else, a gardener’s best weapons against established woody shrub weeds are heavy boots, a good machete, and patience.

Weather Timing

The optimal time to use most weed killers is when there have been several days of dry weather. Otherwise, rain can wash away herbicides and dilute them, rendering them useless.

Another timing-related factor is wind. If you’re applying a broad-spectrum herbicide such as glyphosate herbicide, for example, winds that are too strong can blow the herbicide in your neighbor’s direction.

Therefore, watch out for wind when spraying with glyphosate herbicide or any other nonselective herbicide that kills all plants, including your vegetables and flowering plants.

What is the Best Time of Year to Use a Weed Killer?

It is best to kill weeds in Spring, then again in Fall. Springtime is ideal because, with Winter looming, this is when the weeds are most vulnerable. Fall is a great season too, since the weeds will not get any bigger. Summer is also great, but do not use weed killers in the Winter because it can cause damage to already established plants.

Why does the time of year affect weed killers?

The best time to apply weed killer is in the spring. Because it is both warm and wet in the spring, weeds are more visible, making them an easier target for your spray can.

The big rains of spring bring out the little weed killer in herbicides, which require absorption by the soil to activate. The wet spring weather makes herbicide absorption the most effective time of year.

Without rain, the herbicide solution is like water on the sidewalk--it can’t run off to kill weeds.

Fall or October is the second-best month for weed killers because the weather is a sudden change and weeds can’t adapt. Hence, weed killers thrive in October.

To be clear, not all weed killers are herbicides, such as Foamstream. This herbicide-free weed killer is usable at any time of year, regardless of soil moisture level.

Can I Spray Weeds When it’s Hot and Dry?

Gardeners are divided over when to spray stressed weeds: After an application of water or in dry conditions. Plants--even weeds--have a way of growing in spite of most efforts to stop them. One of the ways they do this is by making their leaves tougher, or getting them thicker; this keeps moisture inside during hot dry conditions.

When plants are under stress, their cuticles thicken to protect their leaves. Ninety-eight percent of weed species respond the same way but the timing and frequency of watering must be taken into account.

Water-stressed weeds have a disheartening way of making a last stand after being sprayed. They send up new, fresh leaves within hours of being hit by the sprayer. And then it’s as if they never had enough water at all.

Gardeners should not expect rainfall to be weed control. The solution is to wait for new leaves to sprout after the rain.

Conclusion

Spray the weed killer when the weather is mild, not extreme. Spring or fall are best because they're seasons in which temperatures aren’t either freezing or so hot that the weed killer will evaporate before it has time to do its job. Don't be greedy; wait eight weeks between sprays -- one in early spring and one in late summer.

In fall, October is the best month to weed because weeds don’t survive winter in the Northwest. Treating your lawn twice a week for two weeks in October will create a lush, weed-free lawn.