Poor or nonexistent grass growth from seeds can be caused by a number of factors. The most common reasons your grass seed isn’t growing are:
- Wrong temperatures for seeding
- Inadequate watering
- Improper seed-to-soil contact
- Traffic on newly seeded areas
- Not enough sunlight
- Soil pH not suitable for grass growth
- Lack of soil nutrients
- Weed killers lingering in the soil
It’s important to diagnose these issues and correct them. Doing so can cause dormant grass seeds to sprout, salvaging your seeding.
Why Some Grass Seed Doesn’t Germinate
Grass seed germinates when it is covered by moist soil with soil temperatures in the proper range. In ideal conditions, you can expect 90–95% of seeds to germinate if you’ve purchased high-quality seeds and have cared for them properly. Below are the common conditions that prevent seeds from germinating.
- Dry soil
- Low soil temperatures
- Low-quality seed
- Poor seed-to-soil contact
It’s important to note that after germination, grass seeds need ideal soil, nutrients, and watering practices in order to grow into a healthy yard. Germination is just the first stage of grass growth.
8 Steps to Take if Grass Seed Doesn’t Grow
If your grass seed isn’t growing within the expected timeframe for the species you’ve spread, review the following factors. Each of these can prevent or stunt grass growth and make growing grass from seed difficult. By monitoring each of these factors, you can grow a full lawn from seed faster and easier than ever.
Monitor Soil Temperature
Soil temperature is one of the most important factors in growing grass from seed. Grass seed simply will not germinate if soil temperatures are not correct for the grass species you’re seeding with. Make sure soil temperatures have been within the desired range for 2–3 days before seeding.
- Warm-season grasses (Bermuda, Zoysia, Centipede) require soil temperatures 65–70℉ (18–21℃).
- Cool-season grasses (Rye, Fescue, Kentucky Bluegrass) require soil temperatures 50–65℉ (10–18℃).
- Soil temperatures are often about 10 degrees cooler than daytime air temperatures.
- Use a soil temperature map to monitor soil temperature before seeding.
If you’ve seeded when temperatures were outside the ideal range for your grass seed type, your seed will lay dormant until temperatures improve. This may be a reason your grass seed has failed to germinate or has not grown uniformly in your lawn.
Water Before and After Seeding
Seeds need water to kickstart their growth. Moist soil causes seeds to sprout, while dry ground will cause seeds to remain dormant. It’s important to spread grass seed on moist ground and water the area consistently.
- Water for an hour before seeding. Soil should be moist down to 6–8 inches.
- Water for 5 minutes directly after spreading and covering grass seed.
- Water for 5–10 minutes at least 2 times daily after seeding.
- Keep newly seeded ground moist down to 1–2 inches.
Your yard may experience patchy growth if there is insufficient water. If new grass sprouts in low areas but does not grow in high areas, this is usually due to a lack of water in high areas. When this occurs, increase watering frequency, watering 3–4 times per day for 5–10 minutes each session.
Cover Grass Seed Properly
Grass seed should be buried ¼–½ inch deep. Any deeper and grass will not grow and break the surface. On the other hand, if you cast grass seed and do not cover it properly with soil, it will fail to germinate. Uncovered grass seed is also prone to be eaten by birds and other animals.
Ensure proper seed-to-soil contact by raking a thin layer of soil over your grass seed and using a lawn roller to compact the soil on the seeds. This will increase germination rate and trigger growth from lagging grass seed.
Keep Off Newly Seeded Ground
Refrain from walking on the ground with new grass seed for at least 4 weeks. It’s also important to take care when walking in areas with new grass. Seeds sprouting under the surface, as well as new grass sprouts, can easily be killed by simply walking on them.
You may be stopping grass seed growth in its tracks by continuing to use your lawn or other outdoor space. Consider it off-limits until the grass is mature and established.
Are you experiencing poor grass seed growth rates in shady areas? Or has cloudy weather since seeding reduced the amount of sunlight your yard receives?
Lack of sunlight can have a few impacts. For one, young grass sprouts need sunlight to grow and grass may die off in shady regions. For another, shady areas or cloudy weather can contribute to lower soil temperatures, resulting in slower or reduced germination.
If large areas of your yard do not receive much direct sunlight, consider using a grass seed blend designed for shady areas. If you are experiencing cloudy weather after seeding and aren’t seeing good results, remain patient. A shift to sunnier days should kickstart your grass seed.
Test Soil pH
Grass seed will not grow well in soil with the incorrect pH. If you’ve done everything else right and you still see weak grass growth, it’s time to test your soil. In addition to at-home test kits, you can send soil samples to a university extension for full analysis.
- Grass grows best in soil with pH 5.8–7.2
- Test soil with a pH kit.
- If soil is too acidic (low pH), use lime to reduce acidity.
- Do not use lime without testing first. High pH can also stop grass growth.
If you’ve experienced poor grass seed growth, correcting soil pH can show vast improvements in the results from seeding. Healthy soil encourages grass to grow and prevents weeds. Just make sure to test thoroughly and to apply the recommended amount of lime or other soil amendments.
The proper soil nutrients are essential when growing grass from seed. New grass needs fuel to sprout and thrive. If you’re not seeing good growth after seeding, it may be time to fertilize.
Use a high-nitrogen, slow-release fertilizer to promote grass seed growth. Lawn-starter fertilizers should also include phosphorus, to encourage young root growth. A good new grass fertilizer will include both of these nutrients to fuel the seeds in their first stage of life.
Often, it’s a good idea to spread fertilizer at the same time you spread grass seed. However, if you’ve already seeded and aren’t getting good results, it’s not too late to fertilize your lawn and boost the number of nutrients in your soil.
Don’t Apply Pre-Emergent Weed Killers
Pre-emergent weed killers kill seeds just as they sprout. Although you may spread them to stop crabgrass and other pesky weeds, these weed killers will also kill your grass seed as it germinates. To make sure you don’t harm your grass, follow these two rules for pre-emergent weed killers and grass seed.
- Wait 8 weeks after applying pre-emergent weed killer to spread grass seed.
- Wait 6 weeks after seeding before applying pre-emergent weed killer.
If applied pre-emergent weed killer less than 8 weeks before seeding, there’s a good chance the pre-emergent has killed the grass seedlings as they sprouted. If this is the case, wait out the effective period of the pre-emergent (8 weeks) and re-seed your lawn.
What to Do When Grass Seed is Not Growing
When grass seed isn’t growing, the most important things to do are to make sure the ground is kept moist and that the grass seeds are buried ¼–½ inch beneath the surface.
Natural factors such as sunlight and soil temperature can slow or prevent grass seed germination, and there’s nothing to do but wait for conditions to improve before you can see results or decide to seed again.
If conditions are ideal and you’ve properly covered and watered your seeds, take further steps to ensure grass seed growth by testing and correcting your lawn’s pH, fertilizing, and stopping all use of pre-emergent weed killer.