Generally, bigger gardens will need larger iron arbors and trellises. If you have a smaller garden, you'd want one that is also smaller. While iron arbors and trellises can add character to your garden or outdoor setting, there's still a limit to it. In most cases, homeowners tend to go for something that is really big. As a result, the iron arbor or trellis will "drown out" the rest of the garden. The key to not overdo things is to find the right size.
A straightforward way of finding the right size is by doing some visualization and measuring. The first step is to visualize the location where you want to place the iron arbor or trellis. Then, imagine the appropriate size and take some measurements. Once you have the dimensions, all you need to do is to shop for the iron arbor or trellis that is a good fit for your measurements.
Another thing that you need to consider is the vegetation. Always keep in mind that vines will add volume, making iron arbors and trellises look bigger than they first arrived. Hence, you need to factor in this information before buying iron arbors and trellises.