Can i use deck blocks with fence if i bury them in stead of cement?

Ist answer is correct, you need to mix and pour concrete around your posts for a fence to ensure the fence is solid. Easy to do, just buy the 40 lb basic concrete mix, or larger bags if you can handle them- get a 5 gallon bucket, pour in about half a bucket of concrete, add the recommended amount of water and mix well. For wood fence posts, always put a bit of gravel at the bottom of the hole so the fence post is not sitting on dirt. Set your post, then pour the concrete around the post, use a rod or strong stick to pack the concrete around the pole. Doesn't have to fill the hole all the way up, though the post will last longer if it does.