Only use a weed and feed if the weed infestation is completely uniform over the entire lawn and all species of weeds targeted will be affected by the herbicide in the weed and feed. This scenario doesn’t occur often, so it is more likely the use of an herbicide and a fertilizer separately will be needed. If the weeds are uniformly spread over the area to be treated, match the appropriate weed and feed product to your grass, the seed you have recently applied or want to apply, and the time of year.
It’s important to know a little about herbicides so you can make the best choice for when to apply seed in an area that has been treated for weeds. The most common types of herbicide in weed and feed products are selective and systemic. Selective herbicides target a species of plant to kill while systemic herbicides work by being absorbed though the roots and then transported throughout the plant, killing it from within. Read the bag label to see what kind of herbicide is used in the weed and feed you are considering using or have used. The bag label will tell you how many days you must wait before applying seed to a lawn that has been treated with that product.
Herbicides can target weeds before they germinate from seed – pre-emergent – or as developed plants – post-emergent. Before you seed, you can use a non-selective, post-emergent herbicide to control any weeds in the area to be seeded. Most of these can be applied up to two weeks before seeding to control any existing weeds. Herbicides should not be used after seeding until the new seedlings are established. Mowing and spot treatments can be used to control weeds until the seeded area is actively growing and requires only maintenance watering. Establishment times vary depending on the type of seed you use and your weather conditions.
Using Weed and Feed
It is important to know what kind of grass you have growing or want to have growing. Certain chemicals act differently on different species of grass and weeds. For example, the common herbicide 2,4-D is toxic to some cultivars of St. Augustine grass (Stenotaphrum secundatum), which grows in the area roughly covered by U.S. Department of Agriculture plant hardiness zones 8 through 10. Another common herbicide, atrazine, is potentially lethal to grass when applied in temperatures above 85 degrees Fahrenheit. Use the instructions on the bag of each weed and feed product to determine how it will affect seeding.
Weed and feed fertilizers are often used in combination with seeding. Weed and feed formulations consist of two components: a herbicide to kill weeds and a fertilizer to strengthen the turf. The herbicide will weaken the grass as well as the weeds and the fertilizer will strengthen the weeds as well as the grass. When applying seed over a weed and feed application, remember that some weed and feeds can prevent grass seeds from growing.
Sara DeBerry is a graduate of the University of Florida holding a masters degree in environmental horticulture and a minor in entomology and nematology. DeBerry has been writing for government agencies since 2004 and has published peer reviewed scientific articles during her studies at UF.
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.
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.
Timing Is Everything
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.
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 Super Turf Builder with Plus 2 Weed Control, now called simply Super Turf Builder with Weed and Feed, contains more nitrogen and phosphorus than plain Turf Builder Weed and Feed, to provide faster green-up. Super Turf Builder contains 29 percent nitrogen, 2 percent phosphorus and 3 percent potassium, while plain Turf Builder contains 28 percent nitrogen, no phosphorus and 3 percent potassium. The active weed-killing ingredients are 2,4-D and mecoprop. Environmental health agencies in some areas list 2,4-D as a chemical known to cause cancer or birth defects, so use with caution.
Subsequently, one may also ask, how long do you have to wait to seed after applying crabgrass preventer?
Sta-Green Crab Grass Preventer specifies that the product can be effective up to 4 months, and recommends that you wait at least 12 weeks after application before reseeding.
Similarly, can you use Scotts Turf Builder on new grass seed? Answer: Scotts Turf Builder Lawn Food would be best applied to an already established lawn versus new seeding.
When to Sow Seed If you must sow grass seed after applying weed and feed, wait at least four to six weeks before doing so to ensure the herbicide won’t prevent the seeds from sprouting.
When can I seed after using Scotts triple action?