Organic Turf Trade has got you covered.

Here’s a quick way to decide which fertilizer plus crabgrass control is right for your yard.

Early Spring Preventative

18-0-4 with .1 Dimension is a 2-application product that should be applied around April 15, when soil temperatures are around 52◦ F. Crabgrass will start to germinate around 55 degrees, so you want to treat before germination to get full preventative results. Apply this product again on May 15.  Apply 4 bags/acre
each time and you will get prevention and ongoing crabgrass control.

Late Spring Crabgrass Control

18-0-4 with .17 Dimension is a 1-application product with a higher amount of Dimension herbicide. Apply around May 15. You can also apply this product after seeding, only if the seed has germinated and you have mowed at least twice. Apply 4 bags per acre for crabgrass control.

Early Spring if you have more crabgrass than grass

Apply 4 bags/acre of 18-0-4 with .1 Dimension around April 15 (52◦ F soil temps) and then follow up with 4 bags/acre of 18-0-4 with .17 Dimension, with a higher percentage of herbicide, around May 15. This will double down on the prevention and ongoing control of crabgrass.

Prepare ahead in the Fall and in very Early Spring

If you are looking to prevent crabgrass before it even starts to grow, consider 18-0-4 with .42 Prodiamine. Apply 4 bags/acre once around April 15 (52◦ F soil temps). This is not recommended if you have a history of heavy crabgrass infestation. This product can also be applied in the fall as it overwinters well and is still available when soils warm up in the spring, so you get excellent crabgrass prevention.