Is this cedar planter box design asking for problems w/ wood movement?

Question

I'd like to build a cedar above ground planters box and have come up with a design that I like. I am fairly new to woodworking and have some concerns with my current plan of using screws+wood glue for all joinery. I only have a mitre saw and am not really that familiar with some of the more advanced joinery techniques.

Here is the design that i've come up with:

I was planning on using a couple of screws per vertical panel attaching to the top frame and bottom frame.

A close-up on the bottom frame itself:

Again, was just planning on using 3" wood screws to assemble the frame from cedar 2x4's with wood glue. The bottom panels here would also be screwed in longitudinally. Is this plan just asking for trouble with wood movement in the future? I'd like for this to last a few years at least and look decent as well, but i don't have access to a table saw nor do i have much joinery experience.

Thanks!

Answer 1

You're right to check about wood movement with the vertical orientation of the boards on the sides, which orients the longitudinal grain horizontally (not vertically as you'd see in traditional chest construction for example).

And if the design had those boards tightly fitted together, or especially if glued-up into single panels, the expansion and contraction could literally break the planters apart.

But you sidestep this problem as you've kept the individual boards separate, the gaps allow each one to expand and contract on its own.

A bit more reading on wood movement from previous Q&As if you're in the mood:
What general considerations do I need to take into account for wood movement?
What is the maximum width for a full cross grain glue up?
Stabilizer for softwood tabletop that bows

Answer 2

This design can work, but you can expect a huge amount of wood expansion once you fill it with dirt and water the plants.

I made a planter just like this. I allowed for 4 inches of expansion, and still had to remove one of the strips and rip off ~2 inches due to expansion from watering.

If you really want to moisture proof this design, cut the panels like floorboards with a tongue and groove, with extra long tongues and extra deep grooves. If you can't do that, sealing each board with a waterproof seal should help reduce expansion, but you still need to allow for a few inches.