John Gardener
Hi Alex, you have a few options here. Depending on the height of your raised bed & which way you are laying your sleepers. 1. Concrete fence posts (cut to the required height) into the corners & if required middle section of the sleepers. Then screw/bolt the sleepers to the fixed posts. 2. You can buy ground spikes specifically designed to secure sleepers. Check toolstation/screwfix etc. 3. In most cases the weight of two or more sleepers will be sufficient to holdback a bed of day 200-600mm depth (if laid flat not side on) I have some examples of work I have done on raised beds on my profile. I hope this helps, good luck. John GreenVale
