Weed management should be completed before seeding the lawn with a non-selective herbicide seven to 14 days before you till the soil. A second application of the herbicide may be required to kill any weeds you missed during the first treatment. Wait another seven days until tilling the soil if a second application is used.
A general rule of thumb is to wait at least until you have mowed the new grass four times before using any standard postemergent broadleaf herbicide. A standard pre-emergent herbicide should not be applied until at least three to four months after seeding the area.
Some pre-emergent herbicides can safely be used during seeding and usually come mixed with a seed starter. These products have the active ingredient Siduron – also known as Tupersan – that works by suppressing weed seeds while improving root development of the new grass. The fertilizer and pre-emergent herbicide mix is applied with a drop or rotary spreader using a rate of 2 1/2 pounds per 1,000 square feet. The spreader setting and actual application depends on the brand of starter fertilizer plus weed control you use, and you should always follow the instructions found on the label.
Weed Control after Seeding
Before you plant grass seed, you should always prepare the area by removing any weeds that may be growing in the location. Even with careful preparation of the planting site, weeds can still develop among the newly planted grass seed. Weed killers, however, can harm grass seeds and seedlings if applied too early or improperly.
Remember that all herbicides are different and the exact time you must wait to apply weed killers to newly planted grass will vary from one product to another. Also, some herbicides cannot be applied to certain species of turfgrass. For best results, always refer to the herbicide bottle’s label.
You can control weeds in newly planted grass seed and seedlings without the use of herbicides. Manually pulling the weeds by hand when they first appear keeps them from producing seeds and prevents the problematic plants from spreading, according to the University of California Statewide Integrated Pest Management Program website. They suggest keeping the newly planted grass weed free with proper mowing, irrigation and fertilization. Since newly planted turfgrass has short roots, keep the root zone moist by watering the soil lightly. However, avoid over saturating the soil. After the turfgrass has become established, promote deep and healthy root growth by watering infrequently but deeply.
Marylee Gowans has written about gardening for both online and print publications. She attended the University of Akron, graduating with a Master of Fine Arts in creative writing. In 2009, she received master gardener certification from the Master Gardeners of Summit County, Ohio.
If you have a very small lawn, an alternative to the granular Scotts weed and feed products is the Scotts Liquid Turf Builder with Plus 2 Weed Control. This liquid fertilizer provides a quick boost of nitrogen as well as killing clover, dandelions and other weeds. Simply attach the garden hose and spray the lawn when the weeds are actively growing.
Wait for a calm day when temperatures are not expected to rise above 90 degrees Fahrenheit and no rainfall is expected for at least 24 hours. Water the lawn first to moisten the grass, or start the application when the grass is moist from dew. The product should be applied while weeds are actively growing in the lawn. A second application may be made, but wait at least 30 days — and do not use the product more than twice each year.
This turf builder weed and feed should be applied with a mechanical spreader for even distribution. When using a spreader, Scotts Turf Builder Plus 2 spreader settings vary depending on the device. Set broadcast and rotary spreaders at 3.5, hand-held spreaders on 3 and drop spreaders on 5. Even if you’ve used the turf builder products for years, always check the package directions to ensure that the instructions haven’t changed.
Scotts Turf Builder Plus 2 Liquid
A well-kept, healthy lawn should be plush, free of weeds and diseases, and as green as the neighbors’ envious hearts. Weed and feed products are designed to provide needed nutrients to the grass while poisoning weeds that want to steal the lawn’s food. Scotts Super Turf Builder with Plus 2 Weed Control works on several species of lawn grasses. While the company’s website recommends waiting four weeks to put down grass seed after applying the weed and feed, seeding first means waiting a different length of time before you use the product.
Before applying any fertilizer or herbicide product, put on a mask, safety goggles, gloves, long sleeves, long pants and closed toe shoes. After applying the weed and feed and cleaning the spreader, wash your clothing in hot water and detergent to remove any dust or residue.
If you are unable to find Super Turf Builder Weed and Feed, Scotts Turf Builder Triple Action provides similar results. It kills weeds, prevents the new weeds from sprouting and feeds the grass.
The Scotts website question-and-answer section states that grass seeds should be allowed to germinate and grow tall and strong enough to be mowed four times before you apply weed and feed. No entirely specific time period is provided, because different grass species grow at different rates, and growth is affected by many variables, including soil quality, temperature and rainfall or manual irrigation.
In general, grass species are divided into two categories: warm season and cool season. The seasons do not refer to the time of year, but the climate and average soil temperature range.
Maintaining a healthy lawn includes mowing, weeding, watering, and fertilizing. However, fertilizing isn’t always necessary. Over-fertilizing your lawn will make the grass grow more vigorously, causing you to have to mow more frequently or lead to run-off which ends up in your local watershed.
Cool-season turfgrasses grow best with average soil temperatures between 60 and 75 Fahrenheit. Cool-season grasses thrive in the cooler climates of the Midwest and Northern regions of the United States. Some cool-season grasses are Kentucky bluegrass, perennial ryegrass, and tall and hard fescue.
What to Consider When Choosing the Best Weed and Feed
To grow a lush lawn, your soil needs to have essential nutrients. Fertilizers temporarily add nutrients to the soil. Fertilizers denote their nutrient ratios as NPK. This denotation represents the percentage of nitrogen (N), phosphorus (P), and potassium (K) in the product. This is how the nutrients help grass:
There are at least 11 states that ban phosphorus fertilizer use or sale. Luckily, many lawn weed and feed products available have adapted to this and have removed phosphorus from the product. Don’t worry—the weed and feed will still green up and thicken the grass without the additional phosphorus.
Some weed-and-feed options out there feature slow-release formulas so you don’t have to fertilize as often. However, to achieve good results plan on treating your lawn at least once every 8 weeks from the start of spring.
Weed-and-feed products come in two forms: liquid and granular. Although the liquid forms are easier to apply and provide faster results, it’s more economical to use the granular form. Spray or liquid weed and feed are designed for small yards.