In most areas, a pre-emergent should be applied on lawns between March 15th and May 15th, depending on where you live. Crabgrass starts to germinate when the soil temperature reaches about 55 degrees. An indicator of when to apply your crabgrass preventer is when the forsythia blooms. For controlling crabgrass, you have three choices:
1. Jonathan Green Crabgrass Preventer plus Green-Up Lawn Fertilizer - Controls crabgrass and other grassy weeds before AND after they germinate, while feeding your lawn gently for up to 8 weeks. This product also prevents certain broadleaf weeds if applied before they germinate. Apply as the first step in my Annual Lawn Care Program with 4 Easy Steps. DO NOT SEED with this product.
2. Jonathan Green Crabgrass Preventer plus New Seeding Lawn Fertilizer - Use if seeding this Spring. Controls crabgrass and provides New Seeding Lawn Fertilizer. You can apply this product on the same day that you sow grass seed.
3. Jonathan Green Organic Weed Control plus Fertilizer - Safe to use around children and pets! Controls crabgrass and over 20 other grassy and broadleaf weeds organically while feeding your lawn, using the patented technology of Corn Gluten - contains no manures! Apply in spring BEFORE these target weeds germinate. DO NOT SEED with this product.
TIP: Proper mowing of your lawn is an important part of controlling crabgrass. Mowing heights of 2-1/2" to 3-1/2" will keep the desirable lawn grasses strong. If you cut your lawn below these heights, it tends to stress the good turf grass and allows crabgrass to take over, since there is less competition.