Building a fixed raised bed is the recommended method for installing a FarmBot outdoors. In these instructions we show you how to build a simple but sturdy bed suited for FarmBot Express or Express XL. This design will fit into most yards, look great, and last a lifetime.

express fixed raised bed express fixed raised bed express xl fixed raised bed

8-12 hours

This is the estimated time it will take to build a fixed raised bed.

Maximum raised bed size

The reference designs shown on this documentation page are for a maximally sized fixed raised bed for the stock Express and Express XL kits. If you are designing a bed for a smaller installation, you will need to modify the dimensions of the lumber and post hole layouts.

We recommend building your raised bed as large as possible to get the most value out of your FarmBot. See the economies of scale section for more information on maximizing FarmBot value.

If you are going to modify our reference design, use the dimension guidelines below to ensure compatibility with the FarmBot.

Model Outer Bed Width Outer Bed Length
Express 1.13m max 3m recommended
Express XL 2.3m max 6m recommended

Do not exceed the max width

While you can adjust a FarmBot to accommodate smaller width beds, you cannot adjust it for beds larger than the maximum width listed.

Longer length beds are OK

While FarmBot Express and Express XL kits only include enough hardware to allow for gantry travel up to 3m and 6m respectively, creating a longer length bed will not prevent the system from being installed.

Step 1: Acquire materials

Express bed (1.13m x 3m)

Qty Component $/Unit Subtotal
6 Posts (90mm x 90mm x 600mm) $3 $18
2 Long walls (40mm x 300mm x 3000mm) $15 $30
2 Short walls (40mm x 300mm x 1050mm) $7.50 $15
2 Cable carrier supports (40mm x 60mm x 1500mm) $4 $8
20 M10 x 100mm lag screws $0.75 $15
20 M10 washers $0.25 $5
1 Box of 90mm wood screws $8 $8
1 Sealer, stain, or polyurethane $20 $20
  TOTAL   $119

Express XL bed (2.3m x 6m)

Qty Component $/Unit Subtotal
12 Posts (90mm x 90mm x 600mm) $3 $36
4 Long walls (40mm x 300mm x 3000mm) $15 $60
2 Short walls (40mm x 300mm x 2220mm) $10 $20
2 Cable carrier supports (40mm x 60mm x 3000mm) $6 $12
36 M10 x 100mm lag screws $0.75 $27
36 M10 washers $0.25 $9
1 Box of 90mm wood screws $8 $8
1 Sealer, stain, or polyurethane $20 $20
  TOTAL   $192

Step 2: Dig post holes

Dig post holes according to the diagrams below. A post hole digger and pick axe can help with tougher soils.

Maintain access

Position the raised bed such that you will be able to access all sides of your FarmBot and garden.

post hole diagram for farmbot express bed post hole diagram for farmbot express bed post holes for farmbot express bed post hole diagram for farmbot express xl bed post holes for farmbot express bed

Step 3: Prepare the materials

Cut all of your lumber to the lengths shown in the table in step 1. Sand all of the wood surfaces to remove any markings and splinters.

Take extra time to sand the top surfaces of the long sides of the bed

FarmBot Express uses wheels to roll directly on top of the long sides of the bed. Knots, large splinters, and other surface defects in the top surfaces can cause the FarmBot to stall, or just have a more difficult time moving across the bed. Use a belt sander or circular sander to ensure there are no defects or uneven areas on these surfaces.

If desired, stain the wood or apply a protective coating of your choice.

Step 4: Postion the posts

Place all of the posts in the holes. The top of the posts should be positioned 300mm above the ground.

Importantly, all of the post tops must be level with each other. Dig out or back fill each hole as necessary to ensure the tops of all posts are level and the correct height off the ground.

posts positioned express posts positioned express posts positioned express xl

Step 5: Attach the short walls

Clamp a short wall to the posts on one of the short sides of the bed. The posts should be flush with the top edge and ends of the short wall. If you are building an XL bed, also clamp the middle post to the short wall.

Drill appropriately sized holes for the lag screws or bolts you will be using. There should be two holes per post. The upper holes should be positioned 50mm from the top edge of the short wall. The lower holes should be positioned 50mm from the bottom edge of the short wall. All holes should be center-aligned on the post.

drill short wall express drill short wall express drill short wall express xl

Attach the short wall to the posts using M10 x 100mm lag screws and M10 washers or equivalent. Once the wall is fastened to all of the posts, you may remove the clamps.

attach short wall express attach short wall express attach short wall express xl

Repeat for the second short wall on the opposite side of the bed.

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Step 6: Attach the long walls

Clamp the long wall(s) to the posts along a long side of the bed. The ends of the long wall(s) should be flush with the outer face of the short walls. If you are building an XL bed, the two long walls must meet at the middle of the middle post.

Drill two holes per wall-post attachment point. The upper holes should be positioned 80mm from the top edge of the long wall(s). The lower holes should be positioned 80mm from the bottom edge of the long wall(s).

All holes should be center-aligned on the post except for where the two long walls meet: these holes should be positioned 17.5mm from the ends of the long walls to best share the common post.

position the long walls for express position the long walls for express position the long walls for express xl position the long wall flush position the long walls for express xl

Attach the long wall(s) to the posts using M10 x 100mm lag screws and M10 washers or equivalent. Once fastened to all of the posts, you may remove the clamps.

attach long wall for express attach long wall for express attach long walls for express xl

Repeat for the remaining long wall(s) on the opposite side of the bed.

remaining long wall for express remaining long wall for express remaining long walls for express xl

Step 7: Attach the cable carrier supports

Use 90mm screws spaced every 150mm to attach the two cable carrier supports to the side of the bed where you plan for your FarmBot’s electronics box to be located. One support should be positioned 100mm from the top of the bed and extend from the midpoint to the end of the bed where you plan for FarmBot’s home position to be. The second support should be positioned 20mm from the top of the bed and extend from the midpoint to the other end of the bed.

cable carrier supports for express cable carrier supports for express cable carrier supports detail for express cable carrier supports for express xl cable carrier supports detail for express xl

Step 8: Install tensioning cables (optional)

With larger raised beds, especially those for FarmBot Express XL, it is possible that expansion and contraction of the soil will cause the longer sides of the raised bed to bend outwards, causing track misalignment. If you think that your bed will not be sturdy enough to resist bending, consider adding stainless steel tensioning cables every 3m to prevent the long sides of the bed from being pushed away from each other. The cables should be positioned in the lower half of the bed so as to not interfere with the FarmBot’s tools once buried in the soil.

Step 9: Fill the bed

Back-fill the post holes with native soil, making sure to compact around the posts to reduce movement. Then fill the bed with gardening soil or a mix of native soil and compost, keeping out large rocks and branches. The Express bed will require approximately 0.75m2 of soil, while the Express XL bed will require 3m2.

fill express bed fill express bed fill express xl bed

Congrats!

Your raised bed is now ready for your FarmBot installation.