When to Mow New Grass

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As a homeowner you will likely have to put down seed to cover any dirt patches or overseed your lawn, especially if there are children or pets frequently trafficking over these areas.

So here are the common question I get: What time will the seed become a lawn? What time can you wait to mow after the seed has been planted?

Considerations for Ideal Grass Cutting Width

Before cutting new grass, ensure that the grass is at least 3 1/2 inches tall. It should take approximately 8 weeks. Be patient! You will need to practice good cutting techniques, and mow hard once you’re able to do the first cut.

Pro Tip: If you haven’t adjusted your lawn mower settings, it may be worth double checking the default height.

Timing of Grass Cutting

You should allow your seeds to germinate for four weeks before you can place the mower on the turf. The leaf blades of seedlings are not strong enough to withstand the compaction and cutting by a mower. Let the turf plants gain strength and age before you cut them.

New seedlings are still trying their best to establish roots in the soil. If you mow too quickly, your mower’s wheels will pull the grass sprouts from the ground. Also, the mower compacts the soil. This prevents seedlings gaining root growth and makes it difficult for them to get into the ground (if done too early).

Sharpen & Clean Blades

Clean and sharpen your lawnmower blades is the most important thing that you can do to your grass.

The grass is effectively cut so that there are open wounds on every leaf. That’s unavoidable. Each wound can be a entry point for pathogens. A clean, sharp blade will reduce the chance of getting a disease. A razor-sharp blade is also a good idea.

New Grass Cutting Technique

To avoid damaging new seedlings, move slowly and gently when you are mowing new areas. They are still growing roots and won’t have attached the grass stems as strongly to the soil as mature plants.

Properly Mulch the New Grass With Old

As long as your grass clippings aren’t clumping, you can leave them behind. They can be used to replenish nutrients and retain moisture, but they won’t add too much to your thatch. If you are concerned about seeding weeds, it is best to dispose of your clippings in a compost or bag them so that they don’t get reseeded.

Only mow new grass when it is dry

Young grass needs to be kept moist to grow. However, it is important to let your grass dry for 48 hours before you mow it.

If the grass blades are allowed to dry, this creates the perfect conditions for your mower’s ability to cut cleanly. The grass blades can become tangled and torn if they are wet.

Do not forget to shut off your irrigation and sprinkler systems

Check Your Grass Type

While the above steps are generally true for most grass types, there are some nuances for different grass seed varieties and growing zones. Be sure to do some local research to adapt this information to your personal lawn conditions.

Summary: When to Cut New Lawn Grass

As a summary, here’s the checklist:

  • Allow at least 4 weeks for seeds to germinate
  • Wait until the grass is at least 5cm long (or 3 1/2 inches)
  • Sharpen and clean lawn mower blades (or ensure they are clean & sharp)
  • Wait until grass is dry (rule of thumb is 48 hours after rain or irrigation)
  • Mow slowly (slower than you normally would) & take turns easy (minimize compacting)
  • Mulch grass clippings (so long as they aren’t bunching and wet)
  • Know your grass type & local growing zone conditions!
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