Step 1 Rest 1 post on edge against wall so bottom sits out 1m. Place spirit level on ground along wide face of post. Run pencil along top to scribe profile of ground on timber. Cut along marked line.
Step 2 Lay first post on top of another, trace angle and cut. Repeat for final post.
Step 3 Place 1 post in position against wall. Mark wall at a height of 1550mm. Using spirit level, transfer this mark to outside edge of post. From there, draw a plumb line down timber. Cut post along this line and use as a template to cut other posts as before. Paint posts with 2 coats of exterior paint, allowing to dry between coats
Step 4 Place posts against wall, so distance between is same as width of drawers. Hold first drawer up between 2 posts about 350mm down from top. Predrill and screw into outside post. Make level and screw into middle post.
Step 5 Hold second drawer against middle post at same level as first drawer and screw in. Make level then screw into third post.
Step 6 Repeat for bottom row, keeping drawers about 30mm off ground and making sure distance from front of drawers to posts is same as top pair.
Step 7 Repeat for centre row, ensuring gap between top and bottom drawers is equal. Paint all drawers with 2 coats of paint, allowing to dry between coats.
Step 8 Drill at least 5 drainage holes through bottom of drawers.
Step 9 Drill through top of posts using a wood bit. Switch to masonry bit, drill into wall, then tap in wall plug. Using 75mm screws, secure posts to wall.
Step 10 Part-fill drawers with potting mix, plant herbs and backfill.