Can I Lay sleepers onto the soil
I want to create a border with sleepers, but not sure if I can just dig a small footing and lay them inside?
Certified GKH Gardening Expert
It is possible, but over a relatively short period of time they soil will rot the wood away. It will be best to line the trench, either with a plastic or other waterproof barrier, otherwise, since you won't want to use treated wood.
This article will offer some information on raised bed gardening: https://www.gardeningknowhow.com/ornamental/bulbs/canna/canna-lily-care.htm