Sowing grass seed is hard work, and you want to make sure that your effort pays off. To grow a full, healthy lawn, you need to water new grass seed regularly, but it's important to understand how much water new grass seed requires and when is best to water.
Like most things to do with gardening (and life!), watering new grass seed is all about balance. You don't want to flood the ground or risk the seeds drying out. We've prepared this step-by-step guide to help you calculate the correct watering regime for your garden, so you end up with the lush, green lawn you've dreamed of.
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Step 1: Check your soil
Before you even start sowing grass seed, it's important to understand what type of soil you're dealing with. Grass seed grows best on loam soil, which is a mixture of sand, silt and clay.
If you're not sure what soil type you have, pick up a handful and form a ball with it in your hands. Sandy soil will immediately fall apart, but if it forms a solid, smooth ball, it's clay. Loam soil is in between the two; it will hold its shape, but when you put the ball down, it will collapse.
Grass seed will grow in most types of soil, as long as you improve it if necessary, but the soil type will impact how often you need to water your seeds. As a general rule, if your soil is sandy, water little and often, whereas if you have clay soil, you can water more deeply but less frequently.
Step 2: Pre-water the ground
Before you sow grass seed, you want to make sure that the soil is moist, but not muddy. Ideally, you'd time your planting for just after it's rained, but if that's not possible, water the ground a few hours before you plan to sow the seeds (or the evening before). You want the water to have had time to soak into the ground. If you can step on the soil without it sticking to your shoe, you're good to go!
Step 3: Water after sowing grass seed
Unless rain is forecast, you should water your grass seed lightly immediately after sowing. Avoid using a jet of water, as this will move the grass seed around and cause the water to puddle on the surface. Instead, choose a light spray setting on your hose. Your aim is to moisten the top inch of soil to aid germination.
Step 4: Watering during grass seed germination
Germination takes 7–10 days for most grass seed mixes. During this time, your main job is to keep the soil moist. If the grass seed dries out, it won't germinate and you will have wasted your time and effort. However, it's important not to overwater grass seed, as if the soil becomes waterlogged, the new grass seeds will die.
How much watering you need to do will depend on the weather. If you get a lot of rain, you may not need to water the ground at all, but if you are experiencing a dry spell, you'll need to get out there with the hose. If the weather is very warm and dry, you may need to water twice a day.
Step 5: The first grass seedlings
Those first few shoots of green popping out of the soil are a wonderful sight and a reassuring sign that your grass seed is germinating. These tiny seedlings are still very vulnerable to drying out and need consistently moist soil. Other seeds will still be germinating, so continue watering lightly once or twice a day until you have full coverage of grass.
Step 6: Small grass seedlings
More of your grass will start to come through over the next couple of weeks. As seedlings get bigger and stronger, they can cope with more water, so you soak the ground more thoroughly every time you water it. You can also ease back on the frequency of watering, though if the weather is dry, you may still need to water your new lawn daily.
Step 7: Mature grass
When your grass reaches a height of 5–7 cm, it's ready for its first cut. Once you've mowed it (use a high setting and take it steady), you should give it a good soak. Continue to water every day or two until it needs to be cut again. You can then reduce watering to once or twice a week for a transition period before easing off altogether.
Step 8: How often to water your new lawn
You are now the proud owner of a new, fresh, healthy lawn! You can mostly relax and let nature take over; however, if the weather is very hot and dry, you may want to water your grass deeply once a week for the first summer.
FAQ
What time of day is best to water grass seed?
Early morning is the best time to water grass seed, as temperatures are cooler and the sun is less strong. This reduces evaporation and gives the water a chance to sink into the soil. If you're wondering how long to water grass seed, about 5–10 minutes a day should be enough for an average sized lawn, either with a sprinkler system or hose.
Can you overwater grass seed?
Overwatering grass seed can cause the soil to become waterlogged, which can drown your seeds. For the first few weeks after sowing grass seed, you want to keep the soil moist but not too wet. Use a light spray setting on your hose or sprinkler so the water soaks evenly into the soil and doesn't pool on the surface.
What grass seed is best for repairing lawns?
Use our hard-wearing grass seed to overseed bare patches due to high usage. If the thin patches are due to shading from trees or fences, then use our shady lawn mix, which is specially formulated to grow well in shade.
