Killing Weeds Before They Sprout
A task that most property owners spend a lot of time managing in the summer months of Colorado is weed patrol. Wouldn’t it be nice to preempt some of those pesky weeds before they ever have a chance to poke their heads out of the soil?
There is a way to slow them down by using pre-emergent herbicides. This method won’t kill established plants but will prevent weeds from growing successfully. This protective barrier only lasts for six to eight weeks, though, so timing is everything.
When to Apply Pre-Emergents
The best two seasons to apply is the spring and the fall, but the herbicide targets different weeds depending on the time of year. Here’s more on the springtime application:
Spring pre-emergent herbicide applications are used to prevent summer annual weeds. Summer annual weeds are both grassy and broadleaf types. For best results apply herbicides when the soil temperature is around 55 degrees or above for at least 36 to 72 hours (ideally this will be two weeks before seed germination). The majority of the USA experiences these soil temperatures from March to April. Consult your local county extension service to get up to date soil temperatures in your area.
Herbicides on Gravel vs Grass
You can freely apply pre-emergent to gravel or rock gardens, but you have to take some steps to protect plants you don’t want to damage. However, herbicide application with grass is a little different. Do not apply pre-emergent to newly seeded grass, as it may prevent it from growing as well.
For established grass, the biggest issue for most people is getting rid of crabgrass and other annoying and unattractive weeks that love your always-watered grass areas. It’s critical that you read the label of the product before putting it on to make sure the list of weeds that are susceptible include the ones you want to prevent.
This video offers some tips for what types of pre-emergents work the best and when to apply them:
As he mentioned in the video, the warmer states are the areas that have to worry about a fall pre-emergent. Again, the timing is key as it won’t do you any good to spread pre-emergent after the weeds are showing. Don’t forget to water in the herbicide within the selected time period or it won’t produce the chemical barrier needed to prevent weed growth.
Organic Pre-Emergent Herbicides
If you are more of an organic gardener and prefer to avoid the chemicals, there are options but they don’t tend to last as long and can be quite expensive. One such type is called Pre-Emerg (formerly called Preem) and the way it works is by burning the seed hairs that are found on many types of weed seeds but doesn’t harm the desired turf grasses.
Another organic pre-emergent is discussed in the next article from The Spruce:
How Does Corn Gluten Work?Corn gluten inhibits seeds from forming roots during germination. The application must be carefully timed before germination of crabgrass seeds, for instance. The seed will germinate and form a shoot, but not a root. Prior to germination, a short drying period is needed to kill the germinated, but rootless, plant. If conditions are too wet during germination, the plant will recover and form a root.
Corn gluten provides no post-emergent weed control. If seeds have already germinated, a late application of corn gluten will only serve as fertilizer for the weeds.Applications of corn gluten should be timed with rainfall. If it doesn’t rain within five days of application, it needs to be watered in with 1/4 inch of water. A dry period of a day or two must follow the watering in to prevent the seedling from growing another root.
Whether you love to work in your yard or prefer to have a Denver lawn care company do the work for you, staying on top of weed control is an ongoing battle for everyone. A little planning ahead can save a lot of headaches and extra work to keep your yard looking sharp.