How long after spraying weed killer can kids play on the lawn?

The short answer

Until the spray has dried. That is the line on every liquid weed killer label read for this page. A glyphosate spray sold for home use says to "keep people and pets out of treated areas until spray has dried"². A 2,4-D lawn weed killer says the same: "Do not allow people or pets to enter the treated area until sprays have dried"³. Neither one gives a number of hours.

Granules are the exception. A weed and feed bag is a dry product, so it cannot "dry". Its label says people and pets may go back "until dusts have settled"⁵. The National Pesticide Information Center (NPIC) sets a stricter line for children: keep them off "as long as granules are still visible"¹.

Three answers circulate online: 4 to 6 hours, 24 hours and three days. None of them is a reentry time on the labels read here. A 3 day figure does appear on the glyphosate label, but it is about grass seed: lawn grasses "may be planted 3 days after application"². A 24 hour figure appears too. It is how long the weed and feed label says to wait before you water or mow⁵. Neither is the time a child has to stay off.

Schools and day cares can be different. In New York and Connecticut, the question mostly does not arise. Both states ban most lawn pesticides on school and day care grounds⁶⁷⁸.

What "weed killer" and "the label" mean here

A weed killer is a herbicide: a product made to kill plants. In law it is a pesticide, the same family as bug sprays and rodent baits. New York's school guidance lists herbicides among the pesticides it covers⁶. Connecticut's child care law defines a pesticide to include "a herbicide"⁸.

The label is the printed directions on the bottle or bag. The US Environmental Protection Agency (EPA) approves the wording when it registers the product. Each product gets an EPA registration number, printed as "EPA Reg. No.". Every label read here also says it is "a violation of Federal law to use this product in a manner inconsistent with its labeling"²³⁵.

The line that answers this page's question is the reentry statement. It says when people and pets may go back onto the treated area. On the glyphosate label it sits next to a "Re-entry icon"². "Dried" is not defined on any label read here. In practice it means the grass is no longer wet with the product.

What four labels say

Here are the reentry lines from four EPA-stamped labels. Three are sprays. One is a weed and feed: a lawn fertilizer with weed killer mixed in, spread as granules.

Three of the four products contain 2,4-D, a common lawn weed killer. When the EPA reviewed 2,4-D, it sent amendment letters to the makers. The 2008 letter for one ready-spray product told the maker to add this line to its directions: "Keep people and pets out of the area until sprays have dried"⁴. Nearly the same sentence is on the 2,4-D concentrate³. So "until dried" is not only one maker's choice of words. The EPA itself required it on at least one product.

Every spray label also says to keep people and pets out during the application. The concentrate adds that the product must not touch any person or pet, "either directly or through drift"³. Drift is spray carried by the wind onto places it was not aimed at.

Granules: the one case where "dry" is not the test

Granules raise a different question, because nothing is wet. The weed and feed label says people and pets may go back once the dust has settled⁵.

The same label explains why that is not the end of it. It says to spread on grass "wet with dew or thoroughly-watered" so particles stick to the weed leaves. Then "Do not water or mow lawn for at least 24 hours after application," because "Granules must remain on weed leaves for 24 hours to be effective"⁵. For a day, the granules are meant to sit on the lawn.

NPIC gives two rules for granules¹:

• If they stay on top, keep children and pets off "as long as granules are still visible".
• If the label says to water them in, keep off "until the granules are completely watered in and the lawn has dried".

A weed and feed of this kind is the first case. Put the label and NPIC together, and the lawn should stay clear for at least the first 24 hours, while the label wants the granules sitting on the weeds. That is a reading of the two sources side by side. Neither one states it as a single rule.

One backyard and one day care yard, walked through

Take a backyard swing set with dandelions in the grass under it. Suppose a parent plans to spot spray them with a 2,4-D ready-spray on a calm Saturday morning.

1. Before spraying. NPIC says to move toys and outdoor furniture so they do not get sprayed, and to cover the sandbox¹. The sandbox lid does that job.
2. While spraying. Children stay inside, "especially downwind from the site"¹. The label says nobody but the person spraying belongs on the area³.
3. After spraying. The children go back out once the treated grass is dry. The label gives no hours, so the test is the grass itself³⁴.

Now suppose the same parent uses weed and feed granules on the whole lawn instead. The label says dew-wet grass helps the particles stick, and it rules out watering or mowing for 24 hours⁵. By NPIC's rule, the granules are still on the lawn for that day, so the children play somewhere else¹. Spread on a Saturday morning, that means Sunday morning at the earliest, and later if granules can still be seen.

Now move the same dandelions to a licensed day care in New York. The spray is not allowed there at all. Most pesticides are prohibited on "school or day care playgrounds, turf, athletic, and playing fields (including the surrounding fence lines)"⁶. Dandelions are not an emergency. The state lists "aesthetic (non-emergency) reasons such as the presence or growth of any undesired species" as a reason that does not qualify⁶. The weeds get pulled or mowed.

In Connecticut, the same day care cannot apply a lawn care pesticide on its grounds either, outside an emergency⁸. If an emergency spray does happen, for ticks say, the law says no enrolled child may enter "until it is safe to do so according to the provisions on the pesticide label"⁸. So the label line comes back as the legal test.

Schools and day cares in New York and Connecticut

New York's rule is the Child Safe Playing Fields Act, Chapter 85⁶. It covers schools and day cares. A short list of products stays allowed:

• Antimicrobial products
• Aerosol sprays in cans of 18 ounces or less
• Non-volatile insect and rodent baits in tamper resistant containers
• Products with boric acid or disodium octaborate tetrahydrate
• Horticultural oils and soaps with no synthetic pesticides or synergists
• Products the EPA classes as exempt from registration

A one-time emergency spray needs a determination from an authorized body: a county or state health department, the state Department of Environmental Conservation (DEC), or a public school board for its own schools⁶. The state says "bare patches and ruts" on sports fields are not an emergency, "even for the students playing on them". An unusual tick infestation is the kind of case that may qualify. Any spraying at a New York school or day care must be done by a DEC-certified applicator⁶.

Notice rules sit on top. Before a non-exempt pesticide is used, schools must send written notice at least 48 hours ahead to everyone on the school's pesticide notification registry. At the start of each school year, schools tell parents and staff how to sign up for it. Day cares must post a notice 48 hours ahead where parents drop off and pick up. It names the product, its EPA registration number and two rain dates for outdoor work⁶.

Connecticut has two laws. For schools, no person may apply a lawn care pesticide "on the grounds of any public or private preschool or public or private school with students in grade eight or lower"⁷. A window that let schools treat playing fields and playgrounds under a pest plan closed on July 1, 2010. An emergency spray needs a ruling from the local health director, a state commissioner or, for a public school, the superintendent⁷.

For child care, the ban covers the grounds of every child care center, group child care home and family child care home⁸. A family child care home is exempt when the licensee does not own or control the grounds. Emergency sprays are allowed for threats such as "mosquitoes, ticks and stinging insects". Parents must get notice at least 24 hours before any application on the grounds. The notice names the active ingredient, the target pest, the place and the date. Records are kept for five years⁸.

What the answer does not cover

This page covers when children may go back onto treated grass. It does not judge how harmful any weed killer is. That is a question about each product, and NPIC asks callers for the EPA registration number or the active ingredients so it can answer for that product¹. Its phone line is on the page cited below.

The labels read here are four home lawn products. A product used by a lawn service may carry different wording, and some products are restricted to certified applicators. Read the label of the product actually used. If a service treats your lawn, ask for the product name and its EPA Reg. No. before the day, as NPIC suggests¹.

No label or source read here sets a longer wait for babies, toddlers or a child who puts grass in their mouth. None says how long "dried" takes on a damp or cool day. Use the dry grass test, not a clock.

The state rules cover New York and Connecticut only. Other states have their own laws, and those were not read for this page. For a school, park or day care in another state, ask the operator or the state pesticide agency. Connecticut's school ban stops at grade 8, so a high school campus is not covered by it⁷. Neither state's ban covers a city park playground that is not part of a school or day care.

What to do next

At home, the next decision is usually how to keep the weeds down without spraying near the play area at all. Planting and landscape around playgrounds covers what to plant beside play space and the weeding it takes. Pulling the weeds under a playset by hand can fit into the yearly look over the set in annual maintenance.

In an apartment complex or HOA, the owner usually hires the lawn service. NPIC's own example is a family who got a spraying notice from their landlord¹. HOA and apartment playgrounds covers who is responsible for those shared spaces.

For a day care, spraying belongs in the same plan as the rest of the yard. Childcare playgrounds covers what licensing expects outdoors, and records and documentation covers the five years of records Connecticut asks for. Disinfecting equipment is a different job. New York leaves antimicrobial products off its ban⁶, and cleaning and sanitizing covers which products suit which surfaces. For ticks, wasps and other pests that can justify an emergency treatment, see insects, animals and contamination.