Maybe you’re seeding new construction, covering some bare patches of soil, or trying to rejuvenate a thinning lawn. Chances are that no matter the case, you’re checking on the new grass seed often to see if it’s sprouted. All while wondering how long it takes until new green sprouts begin emerging.
Sound familiar? If so, you’re in the right place.
On average, most grass seed takes approximately ten to fourteen days to germinate. Under the best conditions, you may see sprouts in as little as five to seven, but it can sometimes take up to thirty days for the grass to grow.
What Affects How Long it Takes Grass to Grow?
The difference in ten to thirty days seems paramount when you’re impatiently waiting for your new lawn. Instead of getting frustrated because it seems to be taking so long for the new seeds to germinate, it’s essential to understand a handful of things that affect germination. These varying factors can either speed up or slow down sprouting time.
These four elements highly impact the time from planting to germination—and the emergence of the new grass through the soil surface.
- Type of grass seed you’re growing
- Germination time for the variety
- Weather conditions
- Soil attributes
Type of Grass Seed
Turfgrasses are categorized into two broad types: cool-season grasses and warm-season grasses. They have different climate requirements and growth habits that dictate the best time of year for planting. If you seed your grass at the wrong time and the climate isn’t ideal for germination, it can significantly impact how long it takes for the seeds to grow.
- Cool-season grasses do best when seeded in the fall (although some recommendations say fall or spring). This type of seed germinates best when it’s a bit cooler, with soils between 50 and 60°F and air temperatures between 60 and 75°F. They aren’t as tolerant of heat as warm-season grasses, so germination slows or stalls when the temperatures are warmer.
- Warm-season grasses should be seeded in the late spring or early summer when soil temperatures are at least 70°F, and air temperatures are above 80°F. This type of grass thrives in the heat, so germination is slower when temperatures are cool.
Typical Germination Time
Plants differ dramatically in how long it takes seeds to germinate. Some of this is genetic adaptations to native conditions, ensuring that seeds only sprout when they have favorable conditions to grow. Turfgrasses are no different. Different varieties of grass vary considerably in how long they take from planting until you see sprouts.
Therefore, it’s important to check the seed package when planting to get an idea of the timeframe for your grass type. The following are germination times for some of the most common warm-season and cool-season turfgrass varieties.
- Bahia grass: 28-30 days
- Bentgrass: 10-14 days
- Bermuda grass: 7-14 days
- Centipede grass: 10-28 days
- Fescue: 7-14 days
- Kentucky Bluegrass: 14-30 days
- Ryegrass: 5-10 days
- St. Augustine grass: 7-14 days
- Zoysia grass: 14-21 days
Weather Conditions
While timing planting to the suitable climate is vital for germination, fluctuations or abnormal temperature and rain during the optimal planting time can impact growth too. If temperatures are significantly out of what is considered normal, or there is considerably more or less rain than typical, you could see it affect how long it takes your seeds to grow.
- The seeds readily absorb soil moisture when temperatures are too low, but germination won’t start. These conditions create the perfect opportunity for fungal diseases and rot,
- Warmer than average temperatures increase evaporation of soil moisture which can negatively impact germination.
- If there isn’t enough precipitation, germination may stop altogether, or if the seed germinates, the sprout may die without adequate soil moisture.
- Too much rain can wash ungerminated seeds away and move newly germinated seeds that haven’t anchored themselves in the soil. High water levels can also cause the seeds to rot before they grow.
Soil Attributes
The pH level and texture of your soil also impact how long it takes for grass seeds to germinate. Since they influence germination and growth, it’s good to know the pH of your soil before planting—and amend it if necessary—and understand your soil makeup and how that impacts seed growth.
Soil pH Level
For germination in seeds, soil moisture must be high enough to trigger enzymatic reactions. However, having enough water isn’t the only requirement for these reactions to proceed. The soil’s pH level also impacts enzymes in the seed or sprout and sometimes causes them to stop functioning outside the optimal range.
- Cool-season turfgrasses usually grow best in soils ranging from 6.0 to 7.2.
- Warm-season grasses are typically more tolerant of acidic soils and like a pH around 6.0.
Soil pH also affects the availability of nutrients and the ability of the newly developing radicle to absorb them. Overly acidic soil has excessive levels of aluminum, iron, and manganese; calcium, magnesium, potassium, phosphorus, and molybdenum may be deficient. Germination is impacted by these deficiencies and inhibited by toxic levels of aluminum.
Soil Texture
Your soil’s texture impacts germination in two different ways. Texture affects water holding capacity: sandy soils dry out much quicker, which can inhibit germination because of low soil moisture; soils high in clay hold significantly more moisture, and this can help speed up germination but also increases the chance the seeds will rot before germinating.
Clay soils can also develop a crust (if allowed to dry) that is hard for the sprouts to push through.
Ways to Increase Germination Rate
- Plant at the appropriate time of year for your type of grass seed, making sure the soil and air temperatures are optimal for germination.
- Make sure your grass seeds are planted at the recommended depth. Seeds have limited energy reserves, and if they are too deep in the soil, they won’t have enough resources to break through the ground.
- Always keep the top two inches of soil moist. As a general recommendation, plan to water the seeded area at least twice daily, if not more, for five to ten minutes.
- Cover the entire seed bed with a layer of organic material (e.g., straw, peat moss, etc.) to slow water evaporating from the soil to help keep the seeds moist.
How Long to Wait Before Mowing New Grass
Once your grass seed takes off and starts growing quickly, you’ll switch to wondering when you can mow your new grass. The timing of that first mowing is important, though, and shouldn’t be based on a number of days or weeks past planting. You should watch your grass and wait to mow until it is three to four inches high.
Waiting until your grass is a certain height gives the roots time to establish and anchor themselves into the ground. If you mow too soon, these tender roots might not be well anchored, and you can pull the grass out of the soil instead of cutting the tops of the blades off. Mowing too early can also cause soil compaction, which prevents the roots from growing outward and down through the soil.
