I am not sure what you mean by "oversand" except possibly a reference to "top dressing" a lawn. Many golf course greens and occasionally home lawns are top dressed using sand. If this is your meaning, then spring or summer is the best time for top dressing your lawn. There is a rule when using sand, however. The rule is not to top dress using a fine grain sand over a coarse grain sand that may naturally be found in your soil. It is well documented to cause problems. The finer sand will fill any gaps and cause a barrier in the soil. Be sure to use the coarsest grain sand you can find, such as agricultural sand. You might consider using compost as a top dressing instead of sand or at least sand mixed with compost. If you are referring to "over-seeding" and not top dressing, then here is how you do that. Over-seeding warm season grasses, such as bermuda grass is common in the southern U.S. And in other warm countries. Over-seeding is performed in the fall about the time the bermuda grass is going dormant. Annual Ryegrass is the most common seed used. The purpose for overseeding is to provide a green color throughout the winter. Cool season grasses, which includes annual ryegrass, thrive in the cooler weather and will remain green when your primary warm season grass (bermuda grass) is dormant. The ryegrass will die back in the spring soon after the bermudagrass emerges from dormancy. Annual ryegrass must be reapplied each year due to its one year life cycle. For more information on top dressing lawn and well as overseeding, take a look at the website Lawn Care Academy. It has step by step instructions on how to topdress a lawn correctly as well as a detailed page on over-seeding. I hope this helps. Russ
