Knowledgebase
Grass seed bs sod #772589
Asked September 21, 2021, 5:27 PM EDT
Baltimore County Maryland
Expert Response
Sod does have its own soil (probably not all of which is technically topsoil) but not nearly enough to sustain it without the yard also having suitable surface soil for it to be laid upon. If the existing townhouse soil is in poor condition - common after home construction and compaction from heavy use - then she can amend it with compost or topsoil. Mix it into the soil surface with a hard-tined rake or a small rototiller, rather than putting it down as a separate layer just on the surface.
After this preparation the sod (or seed) can be laid and irrigated as needed so it can establish and root several inches into the soil underneath. Irrigation and monitoring for water will be crucial for both if we don't get enough regular rain, but it will need to be more frequent for germinating seed than it will for establishing sod since germinating grass seed does not tolerate drying out for long during that process. Sod or seed that is laid on unprepared soil may not establish well and could result in dieback of the turf.
It would be helpful for her to have a soil test performed before (or after) adding amendment and before seeding/sodding. That way, the results will reveal how best to fertilize and if any pH adjustments are recommended for supporting the lawn's long-term health. Information about testing and labs to consider can be found on this page: https://extension.umd.edu/resource/soil-testing-and-soil-testing-labs
Here is the collection of pages about all aspects of lawn establishment and care: https://extension.umd.edu/resources/yard-garden/lawns/lawn-care-and-maintenance
Miri