Understanding Grass Seed Germination – Lawn Care For …

Grass seed germination keeps you in suspense! You get one chance, but you wait weeks to see if you did it right! Are your expectations for the outcome reasonable? Does every little grass seed sprout and grow?

Many factors affect grass seed germination. The success of your lawn project is not completely under your control, but you can do a lot to improve the final result.

Seed germination is simply the growth process that occurs when the seed absorbs sufficient moisture to start sprouting. This is regulated by soil temperature according to the variety of grass. The hull, or hard outer casing, may delay this process until conditions are favorable.

Once germination begins, if the environment changes significantly (like being too hot and dry), the seed or sprout will die. It cannot start to grow, then stop because something is wrong, wait till conditions improve, and then continue the process.

Moisture Adequate moisture must be present throughout the process. Too little and the seed can dry out. Too much moisture and the seed can rot. Read the article Watering New Grass Seed for guidelines.

Warmth Soil temperatures should be in the appropriate range for the variety of grass. Cool season grass requires a minimum range of 45 - 55 degrees. Warm season grass requires a minimum 55- 65 degrees. Note that soil temperatures are usually cooler than air temperature. In addition to the density of the ground that is slower to warm up, moisture evaporating from the surface has a cooling effect.

(Editor's note on soil thermometers: These are extremely useful tools for any active gardener who regularly invests in new seeds and bedding plants, especially vegetable gardeners. There is no way to accurately gauge soil temperatures by rule of thumb. The Luster Leaf 1618 Rapitest Soil Thermometer is an inexpensive but reliable model that eliminates the guesswork and improves your success rate with lawn grass seed. This model is a traditional glass tube that has enough separation of the numbers to easily read within a couple of degrees. Other models I have checked have a dial (like a meat thermometer) that has too large of a range (over 200 degrees-in case you want to baste your soil?) and is not as accurate. If you use the #1618 soil thermometer in loose garden soil it will penetrate easily. In compacted soil, realize that it is not designed to force it in, so use a screwdriver or some time of poker to make a starter hole. Don't make the hole overly large as you want full contact with the soil.)

Oxygen When the sprout breaks through the seed, it requires oxygen for its growth process. When soil is over saturated with water, oxygen is not present and the sprout cannot grow. Compacted soil can also contribute to this problem.

Light A seed has limited resources to support growth while below ground. The sprout must break through the surface in order for the photosynthesis process to function and create food for the plant. Sprouts will not be able to reach the surface if seeds are buried too deep.

This chart may indicate the amount of time until grass first appears, or until the majority of seed has sprouted. Growing conditions greatly affect this process.

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Understanding Grass Seed Germination - Lawn Care For ...