This mounting plate has a stake built in so you can plant this into your planter. 

What you need:

• Pi Zero W, 2W or regular zero
• 4x M2.5 x 8 (or 6 or 10) and some standoffs (like the ones in this kit)
• Pimoroni Grow Kit or whatever sensor kit you want

Printing

• Print with the mounting face on the build plate (see example picture)
• Use supports to print

Assembly

• Run the 4 screws through the mounting plate hole, the zero should mount facing upward
• Secure the Pi using the standoffs
• Attach the hat
• Stick into the planter