Still early, but want to get a schedule down and head start this Spring to control crabgrass and weeds in my lawn. I live on the border of Zone 5 and Zone 6. Over the winter, I've been slowly buying bottles of Ortho Lawn Weed Killer Plus with Crabgrass Killer --- the bottle that you attach to the end of a hose. I have 3 acres, but am only interested (at this time) to create a nice lawn just around the house; maybe 1/4 - 1/2 acre. Question is, when would be the ideal time to apply this? I'm thinking mid-April for my Zone(s), but am not sure if that is too soon or should I wait until early May? Also, should I fertilize before applying or after?
Pre-emergent fertilizers/killers are going to do you some good in stopping crabgrass. I'm not sure if they make a pre-emergent that you put on the end of your hose. Once crabgrass gets a foothold into the growing season, it's hard to make it go away. Crabgrass is an annual, so if you can stop it from sprouting in the spring, you won't have to worry so much throughout the summer. Also, leave your cutting blades up high - the taller the "good" grass the better it does choking out the crabgrass.
Here's a quick clip from wikipedia that might help:
These species often become problem weeds in lawns and gardens, growing especially well in lawns that are watered lightly, underfertilized, poorly drained, and growing thinly. They are annual plants, and one plant is capable of producing 150,000 seeds per season. The seeds germinate in the late spring and early summer and outcompete the domesticated lawn grasses and expand outward in a circle up to 12 inches in diameter. In the fall when the plants die they leave large voids in the lawn. The voids then become prime areas for the crabgrass seeds to germinate the following season. Biological control is preferable over toxin use on lawns as crabgrass emergence is not the cause of poor lawn health but a symptom, and crabgrass will return annually if the lawn health is not improved by fertilization and proper watering. Crabgrass is quickly outcompeted by healthy lawn permanently because as an annual plant, crabgrass dies off in fall and needs open soil without other vegetation for the germination of its seeds the next spring to survive.
I'm currently fighting this on my lawn too. We moved in almost 2 years ago, and the lawn was in a very bad way. The house sat empty for about a year, so the back yard just became a weed field. Unfortunately, you can't do a very effective job to get rid of crabgrass in one season.