Ask Mr. Smarty Plants

There would seem to be three different approaches to discourage geese: prevent geese from having access to selected plants, make the area unattractive to geese, and drive geese away.

If your sunflower house is located at some distance from your main viewing points you might try erecting a fence of wire having mesh that is thin enough to be almost invisible from a distance.

A different approach would be to make plantings that do not suit the geese's life style.  This article from a Seattle newspaper offers good tips.  Principally, minimize the availability of new plant shoots (which geese love) by replacing mowed lawn with taller grasses, sedges or forbs and restrict the birds' easy access to water by planting floating aquatic plants at the pond edges.  If you can do these things before the geese discover your yard and settle there they may never find it a comfortable home-away-from-home.

A final suggestion would be to get a goose dog.  Finding one that would reliably chase the geese but not catch them might be a bit tricky.  But a dog plus a few taller plants harboring potential hiding places for it could make geese uneasy enough to leave.

Suggested aquatic plant species for your area are listed here (you can also use this web page to look for other types of plants for your garden).  Many of them should be available at your local plant nurseries.