There are several ways you can secure your new arbor to the ground, from lightweight to ultra-permanent. But rest assured, any of the options are easy for the average consumer to complete if the steps are followed carefully.  On the lightweight side, you can drive treated lumber or metal stakes into the ground at each leg of the arbor (minimum of 2 feet deep) with the top of the stake below the final grade surface. The arbor legs can then be screwed or bolted to the stake.  Midweight installation methods use a 24” screw anchor twisted into the ground at each arbor leg a few inches subsurface, with each leg bolted to the screw anchor. You can obtain a more permanent installation by digging a 6” diameter hole with a post-hole digger below the frost line for your area. Fill it to a few inches below surface level with a bag concrete mix, and plant a pipe or post in each concrete pad that will extend up into each leg of the arbor. Once the concrete is set up, slip the arbor legs down over the posts. Drill into the leg at a sub-surface level and bolt it to the posts. Use permanent installation methods for swing arbors, seat arbors, gate arbors, or any substantial structure susceptible to wind or other lateral forces.