One of the wild grasses you will see growing in your lawn in early summer is Crabgrass. At first, small lime green shoots seem to sprout in hot, full sun areas of your lawn. No, the grass fairy did not come by and add new grass seed. This annual grass is thought to be brought to North America by European settlers as a feed for cattle and other livestock. Once here, the settlers were shown a crop called corn and therefore they abandon their crops of crabgrass and gave us this unwanted weed. This grass, if left unchecked will produce hundreds of seeds per plant, growing each summer & dying in the fall. A single plant will look like a large crab by the end of the summer with as many as 125,000 seeds. These seeds may lie dormant (for years in many cases), until conditions are just right; which is hot, dry weather, usually mid July in Southern Ontario.
Controlling crabgrass is a lot of work, with pulling as many plants out as possible along cement sidewalks, boulevards, curbs, and hot dry areas of your lawn. This task may seem impossible in some lawns that have been let go. Hot boiling water will kill this plant if you have large patches, which would take hours to remove by hand. Some of your good lawn may be damaged but with topdressing & seeding this area after the crabgrass has died, the lawn will look great. This method also works in cement cracks and patio stones where this grass begins to grow. Remember this is a game of numbers, and with every plant you pull or destroy you will have less to deal with in following seasons.
Finally, applying Corn Gluten, a total organic product, to your lawn once in early spring and again in the fall, will stop some germination of this seed, as well as other weed seeds. Corn Gluten may take up to 3 seasons of application to gain good control. Unfortunately, it may also stop the germination of good grass seed. Topdressing or mixing grass seed with a weed free soil is the best way to a great lawn.
Fertilizing at least 4 times a season, spring, early summer, late summer and fall, will also help thicken your lawn to stop all weeds from growing. Watering is also very important! Do not let your lawn completely dry out, as this will trigger the germination of even more crabgrass.
I hope this information helps, and good pulling!