Many folks love to be surrounded by things that are old (but not decrepit). Thus there are aficionados of antique lamps, classic cars, and houses that date back centuries. When we can't get the real McCoy, the next best thing is something that looks old (think distressed furniture). Along the same lines, many of us admire the look of old gardens, in the absence of which we'll settle for a garden that just looks old.
"Walking through gardens designed and created decades ago can fill you with both enthusiasm and despair that you will never be able to recreate the feel of substance that age brings to a garden," observes Marie Iannotti. But About.com's Gardening Guide has some tips in this article for making your garden look old, ranging from the use of weathered objects to ground covers.
Because stone is one of the oldest substances around, stone landscaping immediately makes a garden look older. Another element whose presence assures the viewer the garden didn't just spring up overnight is moss. Combine the two (by growing moss on your stones) and you can practically convince people that the garden has been there forever....
Related resource: Ground Covers

Comments
Our garden has an old bicycle with a basket as an ornament leaning up against a fence. My mom has planted flowers in the basket. It is a really great focal point. I also used some led landscape lighting fixtures to highlight the bike and flower after dark.
I used a below grade LED well light to light the bike. It created a great silhouette on the fence and the fixture is below grade so the led source is hidden during the day not affecting the “old look” of the landscapes. A great combination of old and the new technology of led lighting.
Cheers!