It can be challenging to garden successfully at the beach, but your garden can thrive with proper preparation. The first thing to do, if you have not done so within 3 years, is have a soil test done. With this baseline you will know what amendments are needed. Delaware soils tend to be very acidic, requiring lime.  Also, sandy soils benefit from the addition of organic matter, compost or manure, to help retain moisture and provide nutrients. This is the website for detailed instructions on obtaining a test from the university:  http://ag.udel.edu/dstp/index.html

There are a number of lists recommending trees, shrubs, and perennial plants for sandy seashore sites.  On the University of Delaware website there is a series of documents entitled ‘Livable Delaware’, covering a variety of plant and environmental conditions.  The booklet on ‘Livable Plants for the Home Landscape’ has a section specifically addressing gardening in a salt and sandy location, including plant recommendations. This information can be found at:

http://extension.udel.edu/lawngarden/commercial-horticulture/landscape/

Lists on plants for the seashore from other universities include Cornell and North Carolina:

http://www.gardening.cornell.edu/woodies/pdfs/seashores.pdf

http://content.ces.ncsu.edu/plants-for-seashore-conditions/

You might want to try raising vegetables in containers or raised beds, this website provides detailed information:

http://aggie-horticulture.tamu.edu/vegetable/files/2010/10/E-545_vegetable_gardening_containers.pdf