Question
I live in north-central Massachusetts.  The lawn in the front of my house is original to when the house was built (1997).  The soil is maybe 2-4 inches of dirt, and below that it is 100% sand.  The condition of this part of the lawn is very poor.  There is a mix of many different opportunists/weeds, some bare spots, very little grass, etc.

I need advice on how best to get this area looking good again.  Do I need to add soil?  Do I need to till the existing stuff?  What about hydro-seeding?  Any other ideas/advic?

Many Thanks,

Steve A. DiCastro, MD  

Answer
If you can add enough soil to provide for a 6-8 inch deep base it would be perfect but the lawn should be able to grow in 2-4" of soil.

While watering recommendations are to water infrequently and deeply (a deep soaking less frequently is more effective than frequent shallow applications) you may have to water more frequently on a sandy base. Still water deeply (so the soil is damp to a dept of 4-6". However, in hot summer months, you may need to water 2-3 times per week.

I recommend that you till the top of the soil and mix it with the new topsoil (if you bring in new topsoil). Hydroseeding is one way (not necerssary for good results but it does have its advantages).

The most important thing to remember is that a newly seeded lawn must be kept consistently damp until the new grass has germinated (sprouted). If the seeds are allowed to dry out they die. Therefore, it is best to water several times per day (shallowly) to ensure this. Hydroseeding improves your odds, but you must still water. Once most of the grass has germinated, gradually transition to an infrequent and deep pattern which is how you water a mature lawn, but do allow for your sandy soil (e.g. you may have to water more frequently than people with clay soils for example).

Fertilize in late spring, early fall and late fall. Use a fertilizer w/ slow release nitrogen if available. Do not fertilize during hot summer months.

Mow frequently and mow high. Mow the lawn 2.5-3.5" tall. This helps keep humidity in which is especially important on a sandy soil base.

Before seeding, I suggest you kill of the weeds with Round-Up (glypsophate). Once the herbicide dry, it is no longer active. You do not have to worry about translocation in soil. Avoid spraying on windy days and watch out for flowers, shrubs, etc.