Updated February 14, 2023:

If you’ve decided to install artificial grass, first, congratulations on making a wise, water-saving decision. Not only will artificial grass help to significantly reduce your water consumption, but it also provides you with a beautiful, functional lawn that will pay for itself in just a few years.

Once you’ve determined where you want to install your artificial grass and the dimensions of your soon-to-be-amazing new lawn, it’s time to start excavating your existing soil. Excavating soil is a critical step in a proper artificial grass lawn installation. The native soil that will be excavated will be replaced with a sub-base.

But, you may wonder, why do I need to install a sub-base? Why can’t I just install my artificial grass on the soil as is? The answer has to do with some basic scientific principles – expansion and contraction. Soil naturally expands and contracts over time depending on climate. For natural grass, this presents no problem because it is growing in the soil. For artificial grass, however, such expansion and contraction can result in buckling, wrinkling, and an uneven surface.

The solution for preventing this is to replace the soil with a substance that will not expand or contract. A proper sub-base comprised of either class II road base (also known as crushed miscellaneous base or CMB) or decomposed granite will provide an excellent foundation for your artificial grass and will help ensure you get the most out of your investment.

CMB is a blend of recycled concrete and/or recycled asphalt and consists of a sand-gravel mixture of varying-sized particles up to ¾ of an inch in size. Decomposed granite, or DG, is granite rock that has weathered to the point that it readily fractures into smaller pieces of weak rock and/or into mixtures of gravel, sand, and silt-size particles of clay. Both are great materials for your sub-base. CMB is more easily compacted than DG but doesn’t drain quite as well. DG, meanwhile, yields a smoother finish than CMB but it is quite a bit more expensive. Generally, CMB is the best choice for artificial grass in landscaping while DG is the best choice if you’re installing a putting green.

Once you’ve decided on the appropriate sub-base material, it’s time to shake a leg…and everything else too! After you’ve spread the sub-base material over your installation site, your best option for a proper installation is to use a vibratory-plate compactor. You may also opt to use a roller and a hand tamper to get those hard-to-reach areas and tight corners. Oh, and be sure to wet down your sub-base as you’re compacting it to help remove any voids or air spaces.

Adding a sub-base may seem like a lot of extra work. But like anything worth doing, it’s worth doing well. Installing artificial grass the right way the first time will be beneficial in the long run. For more information on the installation process, check out our artificial grass installation videos or come on down to your local Purchase Green store. We’re happy to help you figure out which sub-base is right for your and how much you need for your installation.