I have seen many pictures where people who have used wooden timbers such 4x4s to build trellises, bean poles, and other structures.

I was wondering: if I want to use wooden timbers to make a structure or pole, can I just sink it directly into the soil (i.e. no concrete or anchor, just stick it in a post hole, then pack earth around it)? The main concerns I had about this are 1) that it might not be very stable (I can go down about 2 ft maybe) and 2) that having buried wood directly in contact with the soil would cause it to rot quickly. Is there an easy way to protect the buried section from rot, if that is a problem?

I garden out of a rented urban plot, and am not able (nor inclined) to set the post in concrete or the like. The structure would only need to survive a year or so. I like the idea of timbers because I can get some cheap, and they are easy to work with as long as durability is not a huge issue.

Thanks again for the tips!

The solution I arrived at for bean trellises is to drive short steel fence posts into the ground. This is easy to do because the tops are not out of reach for striking with a hammer and they penetrate the ground easily. These stakes have a series of holes, making it easy to screw on a vertical wood pole. I use 1x3 furring strips, which are very inexpensive and the right weight for the job. Horizontals can be attached to the verticals if desired.

Jim