One of the common questions associated with planting new grass seeds is, “how do I water new seed?” Truthfully, this is one of the most critical parts of planting grass, so it’s important you consider how long and how often you water it. You want to make sure you give it enough water without giving it too much.
The quick answer to this age-old question is that it depends. The frequency and timing depend on a few factors, but the hard and fast rule is to keep the soil and seeds slightly moist at all times. It is generally recommended to water a couple of times a day (or more) for just a few minutes to wet the soil thoroughly.
Like many other aspects of lawn care, in this case, you need to dig a little deeper into the science behind watering to get an exact answer. Even then, you may have to work through trial and error to find the sweet spot for your lawn.
Why Is Water Necessary for Germination?
Water is essential during germination and the initial seedling growth, but for different reasons than later on. Unlike further down the road, when the grass is mature, in these early stages, the grass isn’t photosynthesizing. It doesn’t need water at this stage to produce glucose but instead for other processes.
- Seeds have adapted genetically to stay dormant and not germinate until the conditions are optimal. They want to germinate and survive, so they won’t start the process if there isn’t adequate water or the temperature isn’t ideal.
- Water in the soil helps soften the hard outer seed coat and activates enzymes within the seed that trigger growth.
- The radicle—the first plant part to appear after germination—needs water in the soil to push its way through and penetrate the surface.
- Young seedlings need water for metabolic processes but don’t have an established root system to take water in, so they need access to plenty of moisture.
Understanding Why Properly Watering Is Critical
The trick to watering new grass seeds is finding that perfect balance between insufficient water and too much water. Because unfortunately, this is yet again one of those cases where too much of something is not necessarily a good thing. Always keep in mind two critical components when watering new grass seeds.
- Too little water inhibits germination completely and kills the sprout once it germinates.
- Too much water can wash away ungerminated or newly germinated seeds that haven’t taken root in the soil.
When is the most critical time for watering new seeds?
The time between when you sow seeds and when you see sprouts emerging from the soil is the most critical in providing adequate moisture. Germination time can range from about a week to a month depending on the grass variety you planted and may take even longer in cooler temperatures.
During this time, if the seed or new sprout dries out, it dies. Because of this, your seeds and seedlings must always have adequate moisture. Once the sprouts peek through the ground, they also send out roots below the surface that can access soil moisture, so they aren’t as vulnerable to dry conditions now. But they still need regular watering until they have established a little more.
How Often to Water New Grass Seeds
The simple advice is always to keep the top two inches of soil moist. How often you water and how long will be based on your equipment (a hose nozzle or sprinkler), your soil type, and the weather conditions. Plan to water the area at least twice daily, if not more, for five to ten minutes.
If your lawn already has an automated sprinkler system, this will make the task more manageable.
- When overseeding your existing lawn, keep the sprinkler on its regular irrigation schedule and set the timer for the sprinkler to come on for one or two shorter bursts during the day.
- When reseeding small areas, leave your lawn on its regular irrigation schedule of once a day, and then water the seeded areas once or twice daily by hand to keep everything moist.
- When overseeding your entire lawn, you’ll want to water everything at least twice a day, preferably.
If you don’t have a sprinkler system, you’ll need to set up hose sprinklers to water a couple of times a day, moving them as necessary to cover the entire seedbed.
Considerations for Watering New Grass Seeds
- Type of Grass Seed: Different types of grasses have varying moisture needs. Seeds of drought-tolerant varieties will typically need less water than the grasses that need more water to stay green when actively growing.
- Local Climate: Areas with milder temperatures or high humidity levels will need less water to keep the soil and seeds moist. However, dry climates need more because they lose water to evaporation.
- Soil Type: Water moves through sandy soils quicker, so they need more frequent watering. Loamy or clay soils have better moisture retention, so they may need to be watered fewer times a day.
- Precipitation Amounts: Areas with regular or consistent precipitation naturally have moist soil, so you don’t have to supplement with as much water. Arid areas need more supplemental water from sprinklers.
When to Stop Watering
After the seeds germinate and push through the soil surface, you’ll want to keep watering them two or three times daily for another week or ten days. Don’t automatically stop watering or cut it back just yet! Remember that seeds don’t all sprout simultaneously because they were buried at various depths or absorbed water differently.
Once that extra week has passed, you’ll want to start moving towards less frequent watering events that last for extended periods. Start watering for 30-45 minutes daily to saturate the soil thoroughly. Then proceed to every other day, and then scale it back further, so your grass is watered two or three times a week.
This less frequent, although longer, watering puts the soil moisture deeper in the root zone, encouraging the grasses’ roots to grow deeper in search of water. In turn, your grass becomes more drought-tolerant and experiences less water stress when it’s hot and dry.
How to Retain Water and Increase Germination Rate & Success
- Topdress the seed bed by spreading a one-quarter-inch layer of compost, sand, or topsoil over it after seeding. This layer will help improve the soil’s water holding capacity and help keep the seeds moist.
- Consider covering the entire seed bed with organic material such as peat moss, straw, or hay. This organic layer naturally holds water and will also slow the evaporation of water from the soil surface.
- Avoid planting grass seeds during the hottest part of summer. Seed in spring or fall depending upon your grass type (e.g., warm-season or cool-season) when temperatures are warm enough for successful germination but not so hot the soil moisture evaporates quickly.
- Water the new seeds during the cooler parts of the day (morning and mid to late afternoon) so less water evaporates.
- When seeding small patches—or if your budget allows for it when working with larger areas—choose coated seeds to improve moisture retention.
- If you need to purchase a sprinkler, look for a quality product that receives high user reviews regarding the watering pattern and efficiency. An oscillating sprinkler helps minimize runoff and evaporation since the water has time to soak into the ground before the next pass of the sprinkler.
