How long is a property survey good for?

What? A real estate agent who lies? Get out.

Just kidding.

Surveys, if done by State Certified & Registered Land Surveyors, are done to exacting standards and 'tolerances' and are essentially good until a revolution ousts one government and installs another one.

(Some notable exceptions would be where 'acts of God' such as volcanic eruptions, seismic shifts and water 'mean levels' change the topography dramatically).

The problem in your case is establishing the 'meets and bounds' of the deeded parcel made to you, when you bought it. (Or, the Lot within the Plat, if it was so deeded).

Original 'corners' are pipes driven into the ground (as the survey is being made by the surveyor) to mark those changes in direction from the proceeding line...essentially marking the containing 'box' of your land.

The problem is, those pipes can be moved by anyone. This happens a lot in "leaps & bounds" surveys or rural areas; and it is the Deed of Title which actually is the instrument of conveyance, not pipes in the ground.

To be completely accurate in todays situations, you need to have it resurveyed, unless you want to risk using old "corner" pipes as true and accurate.

For flowers? Probably not worth the costs & time.

Unless some of the property has had a variance or some of it sold off, then the original survey should still be accurate.