I am planning to redo our front steps in stone and my plan is to essentially have two stone walls on each side of the steps coming down from the entrance. For appearances it would be definitely ideal to keep these walls completely vertical for the aesthetic, but I am worried that the weight of the compacted gravel under the steps will be too much of a force pushing on the wall. PLUS, since were up in Canada, I'm concerned that water that inevitably gets into the gravel will push those walls outwards when it freezes. Is there anything I can do to keep it vertical or is that a pipe dream? Thanks for your help!
I have built many vertical retaining walls. Drainage is the first concern then the height. Code may require rails over several feet (in my area 3' is the max). You did not specify the number of steps or the rise (if more than 3' even with drainage usually reinforcements are required). With some walls this is drilled holes that are pinned together. Some are mortar.
So yes you can go vertical but more information is needed on the height and conditions to give a specific recommendation.
Drainage will keep the water away from the backside. Vertical concrete walls are common but require reinforcing (due to tension forces) and an adequate footing that resists both overturning and sliding. Typically, non-reinforced walls, like the rock wall that you want to do, are often sloped slightly backward. They resist the soil simply through dead weight and gravity. If you want to be sure, consult a structural engineer.