When to Plant Grass Seed. Fall is best for planting cool-season grasses like perennial ryegrass, tall fescue, and Kentucky bluegrass. Daytime temperatures should be averaging between 60 and 85 degrees which translates to soil temperatures between 50 to 75 degrees.
During the summer, when temperatures rise, atmospheric and soil temperatures become too hot for cool-season grasses to grow and flourish. Once temperatures reach 77 degrees, it becomes too hot for root growth, and root growth ceases.
Unsurprisingly, warm-season grasses thrive in warmer climates. These grasses, including Bahia grass, Bermuda grass, zoysia grass, centipede grass, St. Augustine, and other turfgrasses, germinate in air temperatures above 80 degrees Fahrenheit.
If the daytime temperature is below 60°F then soil temperature is below 50°F, making it too cold; if there is frost or still a danger of frost, then it's too cold. If it's too cold, the grass seeds will likely rot.
Typically, turf type tall fescue is most suited for germination and development when air and soil temperatures average between 60F and 75F.
Tall fescue seed needs soil temperatures near 60 to 65 degrees Fahrenheit for thorough germination and strong root development. These soil temperatures roughly correspond to fall and spring air temperatures in the range of 68 to 77 F.
Dormancy can occur in Tall Fescue affecting growth when temperatures drop below 50°. In other words, Tall Fescue will stop growing when dormancy occurs.
Ideal Temperature for Germination
Grass seed needs a warm temperature to germinate and grow. The ideal temperature range for grass seed is between 55-85°F (12-29°C). Anything below 55°F (13°C) will inhibit the growth of your grass seeds, so it's important to keep an eye on the weather forecast when planting.
A box or bag of grass seed that has been stored in very warm conditions, or open to humid summer air, will not hold its viability very well. For the future, your new grass seed will keep best if you store it in a tightly sealed plastic bag or container so it cannot absorb moisture.
High temperatures over 90 can kill the plant inside the seed.
The new grass will not germinate if it's dry. Cool overnight air temps and morning dew will help keep the seeds moist for hours naturally, but it's up to you to keep it hydrated during the day. Use an impact sprinkler or water by hand. Don't soak.
If you put down too much grass seed, you will encourage competition that will cause your grass seedlings to struggle after germination because there will be excessive competition for sunlight, soil nutrients, and water. You'll know if you seeded too heavy when the grass grows in very thick patches.
Is too much rain bad for grass seed? Typically, yes. Heavy rain often leads to soil erosion, which means the top layer of soil is worn down by water.
New grass should be watered twice a day (or more under dryer conditions) to keep the top two inches of soil moist at all times. Water daily until all of the grass seeds have germinated, then it will be ready to begin a regular watering schedule.
Avoid watering grass on a hot afternoon when it's 95 degrees or higher. The best time to water grass is at dawn or in the early evening. Water deeply three times a week instead of a little water daily. Test whether your sprinkler system is watering your lawn evenly.
Excessive heat can cause seeds to dry out too quickly, preventing germination. In order for seeds to germinate, oxygen availability may be reduced by high temperatures. High temperatures can also harm seedlings, resulting in stunted growth or even death.
On hot and sunny days, you'll need to water more often to keep the seed bed damp. Wind also dries out the lawn, so you should water more frequently on windy days as well. If it's sunny, 90 degrees and windy, you should be watering at least 3 times a day.
Grass seed is surface sown, meaning lays and roots on top of the soil, so it does not need to be buried. It's usually broadcast over the ground with a hand or rotary spreader. In order for that seed to sprout, it needs good soil contact, which makes soil quality a major factor in growing a healthy, uniform lawn.
Pennington Bermudagrass yields dense, resilient, heat-tolerant lawns. Zoysia grass, Centipede grass and Bahiagrass also tolerate high heat very well. Bahiagrass tolerates high humidity common in the hot Southeast, as well.
Much like established grass, grass seed will struggle to grow in high temperatures. But unlike established grass, where air temperature is more important, grass seed is much more dependent on soil temps. Most grass seed will germinate when soil temperatures are consistently between 55-70 degrees.
Extreme heat can quickly kill the grass you've been working hard to maintain all year. Dry and dead grass can also catch fire with ease, which can spread quickly to your home. But with some preventative and corrective lawn care, you can keep your lawn, and therefore your home, healthy and safe.
It is a cool season grass. Lawns with Tall Fescue thrive when daytime temperatures are 60-75 degrees. Above 75 degrees Tall Fescue will struggle. Above 90 degrees the grass may go into dormancy to protect itself.
Kentucky bluegrasses and tall fescues are cool-season turfgrasses known to be tolerant to heat (7), and, as expected, the Kentucky bluegrass and tall fescue entries in our study were tolerant to the long period of heat stress.
This will help your lawn to withstand the environmental/heat stress. Tall fescue grass protects itself from prolonged drought by turning brown (going dormant). It's not dead and revives itself when rainfall occurs. However, if drought stays for long enough and the temperatures are too high, it can die.
Water your fescue lawn with 1.5 inches of water per week. Water in the early morning. Watering your lawn once per week deeply is better than frequent shallow watering. Use preventative fungicides.