Crabgrass is one of the greatest frustrations for those of us in pursuit of a healthy, green lawn. Crabgrass is difficult to control due to the ability of each plant to produce large numbers of seeds, the ability of the plants to persist through hot dry conditions, and their ability to rapidly take over open areas of turf created by disease, insects, compaction, wear and environmental stress.

General

Crabgrass is an annual weed that reproduces from seed. The stems lie close to the ground making it difficult to cut them down with a lawnmower. Crabgrass grows in sunny areas becoming unsightly, dense patches that can smother grass.
The most common sites for crabgrass to appear are along curbs, sidewalks or heavily walked areas where turf is stressed. The most significant factor contributing to crabgrass invasion is poor management of turf; this includes mowing too closely, light and frequent irrigation, and applications of high levels of nitrogen.

Eliminating Crabgrass

Sadly, eliminating crabgrass is not a quick affair. It takes a number of years of dedicated work to eliminate it entirely from a lawn and it requires an equal degree of work to keep it away once it is driven back. Since crabgrass reproduces yearly from seed, the best way to break the cycle of crabgrass is to prevent the germination of these seeds in early spring.

Spring application of something known as a “pre-emergence herbicide” is the most effective and easiest control of crabgrass. For a pre-emergence herbicide to be effective, it must be applied 1 – 2 weeks prior to germination. Crabgrass seeds begin germinating when air temperatures rise above 18oC (65oF) for five consecutive days.

Once substantial amounts of seed have germinated and first leaves have emerged, it is too late to apply a pre-emergence herbicide. Pre-emergence herbicides provide effective control for several weeks or months, depending upon rate of application, by forming a continuous herbicide barrier in the soil.

The Battle Continues

It is entirely likely that some crabgrass seeds will escape such treatment and germinate. Given the high number of seeds produced by each mature plant, even a few missed patches will cause crabgrass populations to soar the following year unless you once again apply this herbicide.

Additional Tips

A few other things to consider:

    • To ensure you don’t miss a spot, apply half the needed herbicide material in each of two directions – the second direction should be perpendicular to the first
    • If it is particularly dry when you apply the herbicide, lightly water it in afterward
    • After application, DO NOT disturb the soil surface through raking, dethatching or overseeding
    • When a pre-emergent has been applied, remember that it will prevent almost all seeds from germinating. Therefore, don’t bother seeding or overseeding your lawn until mid to late September when the effects of the herbicide have worn off
    • Avoid cutting your lawn very short during the growing season. A lawn mowed an inch or two higher will create shade that will prevent any rogue crabgrass seeds from receiving the light they need to germinate properly
  
Successful selection of a turf grass requires some knowledge of how the turf will be used, where it will be grown and what level of quality is desired. The positive and negative characteristics of each species of turf grass must be evaluated in order to choose the best one suited to a particular situation. The list below outlines some important characteristics of common turf grass for consideration:

 

Kentucky Bluegrass

Creeping Red Fescue

Chewings Fescue

Annual Ryegrass

Perennial Ryegrass

Growth Pattern

Rhizomes

Rhizomes

Bunch

Tillers

Tillers

Growth Rate

Slow

Medium

Medium

Fast

Fast

Wear Tolerance

Very Good

Good

Good

Very Good

Very Good

Drought Resistance

Good

Good

Very Good

Fair

Very Good

Shade Tolerance

Good

Excellent

Excellent

Good

Good

Description of growth patterns:

      • Rhizomes: Creeping stems which are growing below the surface, producing new shoots and roots at the nodes.
      • Bunch Growth: Plants develop tillers at or near the soil surface, without producing rhizomes or stolons.
      • Tillers: A grass stem developing from a side shoot, at the base of a stem, above the ground.
      • Stolons: A stem, on or just below the soil surface produces new leaves, roots, nodes and stems.
      • Roots: Grass roots are always fibrous (many lateral) branched and no tap roots.

Seeding a new lawn or overseeding an existing lawn is surprisingly easy to do. As with most gardening ventures, preparing the site beforehand and maintaining it afterward make up the bulk of the work – the seeding itself is the easy part!

Choosing Your Seed

Selecting the right seed for your location is incredibly important. If the area is hot and sunny all day, you will want a drought-tolerant mix. If it receives sun for some of the day and shade for some of the day, you can use a super-grow or a sun/shade mix. If the area is particularly shady all day, you can try using a shade mix, but be aware that even the most shade-tolerant grass still needs a fair amount of sun to flourish. If you see moss growing in a shady area, chances are it will out-compete the grass and you should seriously consider doing something different with that space.

When to Sow

It is best to sow either in early/mid-spring or late summer/early fall. Avoid seeding in during the hotter months.

Soil Preparation

Your first task when seeding your lawn will be to work the soil with a rototiller to loosen it up. Heavily compressed soil will make it exceedingly difficult for grass to put out the roots it needs to survive during a hot summer. New homes often have awful, ultra-compressed gravel/clay soil around the building where heavy machinery was moving as the house was built. If this is the case, or if you’ve never planted anything in this location before, consider working in a thick layer of black earth to add some nutritional value before rototilling.

While rototilling, try to pay attention to the slope of your yard. If you come across any depressions or lumpy areas, do your best to flatten these spots out to prevent issues of standing water. Using a rake or hoe is your best bet if you can’t seem to level it out with your tiller alone.

Planting

Once you’ve finished preparing the soil, it’s time to apply your seed. A spreader is almost essential to ensure your grass seed is evenly dispersed. Once you’ve determined how much seed you need for the entire area, you can begin. Spread half the total seed in a north-south pattern across the area, and then spread the second half in an east-west pattern to ensure an even spread (see the diagram at the bottom of this explanation). If you are overseeding or patching, use half the amount of grass seed you would have used for a brand new bed. Also, if overseeding, ensure you remove any thatch in the area before laying down any new soil on top.

Once all of the seed has been used, use the back of your rake or a flat-surfaced tool to gently press the seed into the top ¼ inch of soil, ensuring that it will not be dislodged when you water it. Once this is done, top dress the planting area with a very light layer of black earth. The final step in seeding is to apply a turf starter fertilizer. Turf starter fertilizer usually has a higher second and third number to encourage healthy root growth.

Be patient! A good seed mix will take anywhere between 10 and 30 days to germinate.

Watering

Immediately after seeding, water in your new lawn. Be sure to water very gently so as to avoid dislodging all of your carefully placed seeds. If you have an adjustable spray nozzle on your hose, use a gentle setting (time permitting, using a ‘mist’ setting is actually ideal). You want the soil to be thoroughly wet but not so wet that puddles form or runoff occurs. You will want to keep the new seed consistently moist (but not waterlogged) until grass is germinating across the entire area.

Mowing

Start mowing your new lawn as soon as the grass reaches a height of around 2 inches. In the summer, raise your mower blade to a minimum height of 3 inches. Leaving your grass taller (between 3-5 inches) and instead mowing more often creates healthier and greener lawns and will also help inhibit weed growth.

Lawn Seeding Pattern

Start seeding in a north-south direction. Use half of your total seed in this manner. Sow the second half of your seed in an east-west pattern.