Crabgrass preventer timing in Kentucky, Indiana, Maryland and New Jersey
Spring preemergent windows from Kentucky, Indiana, Maryland and New Jersey extension pages, set beside five other states, with each page's cautions.
By LawnYear editorial team · Published · Updated Windows are read from the extension publications listed under Sources; the dates are approximate.
Approximate dates for your state. Check with your local cooperative extension office before you act.
TL;DR: Kentucky and Indiana put the crabgrass preventer in April, Maryland in March to April, and New Jersey in April, with Rutgers tying the date to when forsythia blooms. The four pages also share cautions about seeding, weed-and-feed products and nitrogen.
What is a crabgrass preventer?
A crabgrass preventer is a preemergent herbicide, one applied before crabgrass germinates in spring. That is why the window matters: it has to open before germination, not after. This site gives no product advice, so read the label and ask your extension office.
The four states here were not covered in our earlier post on crabgrass preventer timing, which was written from Virginia, North Carolina, Georgia, Texas, Pennsylvania, Ohio and South Carolina pages. Missouri, Tennessee and Wisconsin are still missing, because the pages used for them do not give a preemergent window.
The four windows
Kentucky's AGR-212 says crabgrass and goosegrass are normally controlled with a preemergent herbicide applied in April. Purdue's Indiana calendar also says April, for high and medium maintenance lawns, if crabgrass has been a problem. Maryland's calendar says March to April for tall fescue and fine fescue, and adds that more than one application may be needed.
New Jersey is the only one of the four to say what sets the date. Rutgers says to apply before crabgrass germinates, which is mid to late April in central and northern New Jersey and early to mid April in the south, and as soon as forsythia is in full bloom. This site shows the whole of April, which is our reading. For areas with severe infestations or sandy soils, Rutgers suggests a second application in early June for some products.
How the four compare with five other states
Set beside the pages for the other states with cool-season lawns, the four sit in the middle. Georgia opens earliest, with February and March best, and North Carolina says early March. Virginia and Maryland run March to April, Pennsylvania starts as early as March 15 in the southeast, and Kentucky, Indiana, New Jersey and Ohio centre on April. The comparison is ours, made by reading the pages next to each other.
| State | Window | Caution on the page |
|---|---|---|
| Georgia | February and March best, April possible | Not on a tall fescue lawn to be seeded or sodded within 3 to 4 months |
| North Carolina | Early March, sooner in the Piedmont and coastal regions | Written for a tall fescue lawn |
| Virginia | March to April on the chart | Skip it where you plan to seed |
| Maryland | March to April | May need more than one application; not where you plan to seed |
| Pennsylvania | March 15 to May 15 across three areas | Window depends on area |
| Kentucky | April | No weed-and-feed products |
| Indiana | April, high and medium maintenance | Little or no nitrogen; no more than 0.75 lb N per 1,000 sq ft |
| New Jersey | April, with forsythia as the cue | Second application in early June for severe infestations or sandy soils |
| Ohio | First weeks of April, deadline April 25 | Written for northeastern Ohio |
Cautions each page adds
Maryland's calendar and Virginia's chart both say to skip the preemergent where you plan to seed, and Georgia gives 3 to 4 months for tall fescue. Kentucky makes a related point from the seeding side: a spring seeding will likely need a preemergent that still allows seed to germinate, and seedings from late spring to midsummer often fail.
Kentucky does not recommend weed-and-feed products, because the best time for the herbicide rarely matches the best time for fertilizer. Its fertilizing advice is fall, not spring. Indiana comes at the same problem from the other side. If a preemergent goes on in April with fertilizer, the calendar drops the May feeding for high maintenance lawns, and it asks for a product with little or no nitrogen, in slow-release form, and no more than 0.75 lb N per 1,000 sq ft.
Fall seeding sidesteps the problem. Kentucky calls mid-August to late September the best time to seed cool-season grasses, partly because early fall has cool temperatures, fall rains and no crabgrass competition. Its second-best window, mid-February to mid-March and not later than mid-April, is the one that collides with the preemergent month. Maryland seeds from late summer to mid-October, and Indiana's optimum is August 15 to September 15 in central Indiana, so both leave spring free for the herbicide.
Dates, cues and the limits of this comparison
Every window is approximate. Whole months are this site's reading of pages that say 'April', and a state's north and south differ. Rutgers is the one page that points to a plant cue, forsythia in full bloom, and Texas A&M for St. Augustinegrass uses soil temperature at about 55 F for 4 to 5 consecutive days. The Kentucky, Indiana and Maryland pages give months only.
Use the state page for the source behind each window, or enter a ZIP code in the schedule tool. If your local extension office gives different dates, its dates come first.
Frequently asked questions
- When should I put down crabgrass preventer in Kentucky?
- The University of Kentucky says to apply a preemergent herbicide in April, and does not recommend weed-and-feed products. This site shows the whole month, and it is approximate for all of Kentucky.
- When should I put down crabgrass preventer in New Jersey?
- Rutgers says before crabgrass germinates: mid to late April in central and northern New Jersey, early to mid April in the south, and as soon as forsythia is in full bloom. Some cases get a second application in early June.
- Does Indiana recommend a preventer with fertilizer?
- Purdue says a preemergent in April with little or no nitrogen, slow-release, and no more than 0.75 lb N per 1,000 sq ft, for high and medium maintenance lawns if crabgrass has been a problem.
- Can I use a crabgrass preventer where I plan to seed?
- Maryland and Virginia say to skip it where you plan to seed. Georgia says not to apply it on a tall fescue lawn that will be seeded or sodded within 3 to 4 months. Kentucky says a spring seeding needs a product that allows germination.
- Does one crabgrass preventer application last the whole season?
- Not always. Maryland says more than one application may be needed, and Rutgers suggests a second one in early June for severe infestations or sandy soils with some products.
How we read the sources: where a post sets states or grasses side by side, the comparison is ours, made by reading the extension pages next to each other. Every number comes from the page named.