When spring finally starts to hit, or summer calls, or the last days of autumn shine bright, all Steve and I want to do is get out onto our patio for warm nights with good wine and good company. (Each other!)  We had this modern block wall built between our patio and the slope that leads into the next yard, and we wanted to add some contemporary flair to the space while also adding privacy. Ideally, it would be also be able to be repositioned when necessary. What we decided on was long rectangular planter boxes to sit on top of the wall.  We weren’t looking for a rustic look, something more sleek and minimal, which is why we chose the long size. Problem was, we couldn’t find any in the size and length we needed. So, it was time to DIY! Here is our tutorial for our DIY modern outdoor planters.

DIY Modern Outdoor Planters





DIY Modern Outdoor Planters


We wanted planters both 4 feet and 8 feet long to fit in sections of our fence between the pillars. (We also made a baby one with the leftover to fit on top of one of the pillars to block the neighbors gardening supplies.) They were designed to be 6 inches wide and 8 inches high. Obviously, you can customize the size planters you want for your space.


  • 1″x8″ Tight Knot Cedar (Sides)
  • 1″x6″ Tight Knot Cedar (Bottom & Ends)
  • 2×4 (pressure treated) for bracing
  • Deck Screws
  • Exterior Grade Wood Glue
  • Clamps
  • Drill
  • Circular Saw
  • Sander
  • Exterior Stain / Sealer (We used Behr – Slate color from Home Depot)
  • Flex Seal Rubber Coating Spray (Optional)

How to DIY Modern Outdoor Garden Planters

Cut (or have cut) sides and bottoms to the size you have planned. Add wood glue and clamp together as shown.

Pre drill holes and screw together.

Measure the end pieces for each planter individually, as the wood can vary slightly. Cut to size. Glue and clamp, then pre drill and screw.

Here is where we realized after the fact that we needed something more substantial than our original idea. In the photos, you can see we placed a vertical brace half way through the planter box made out of the same 1×6 as the ends. Scratch that. Instead, this is where you measure and cut pieces of the pressure treated 2×4, and use them as the center brace, and also horizontally along the bottom to replace the 2×2 braces we used. Trust us, do it this way. That way, you won’t have to go back like we did, scoop out potting soil and replace those measly little braces with the 2×4’s. Do it right the first time, right? And instead of 2 – 2×2 braces on each side on the bottom (see photo) just make a 2×4 that extends all the way across the bottom.  Place them every 12-18 inches. You will get a longer lasting project this way. Screw the braces into place from both the sides and the bottom.

Drill holes in the bottom for drainage.

Sand. We used a cordless palm sander and 120 grit paper.


So at this point, you have this! Now, depending on the look you want, choose an exterior grade stain and sealer and do several coats according to the label. We chose this dark charcoal grey, but you could choose to do a clear, or about any shade in between. Paint them chartreuse if that works for you!

DIY Modern Outdoor Planters


Totally optional step here. We wanted to make the planters as waterproof as we could so that they both lasted longer, and also wouldn’t leak as much all over our pretty new block wall. We sprayed the interior of the planters with 2 coats of Flex Seal. Seems to have done a good job. This stuff reeks folks. LOTS of ventilation, K?

DIY Modern Outdoor Planters


Then we planted them with modern grasses. Before you ask, the tall one is Juncus, AKA “Blue Arrow Rush” and the short ones are Mondo Grass. Both like wet soil, which is good, since we used the Flex Seal that might affect drainage. Keep that in mind, and also sun exposure and size when choosing plants. We can move the planters so that the taller grasses block off an undesirable view, while the shorter one allows us to still see the river and city lights.


Aren’t they awesome? Best DIY modern outdoor planters we ever made. ;)

DIY Modern Outdoor Planters

DIY Modern Outdoor Planters

Did you enjoy reading about our adventure making these DIY modern outdoor planters! Then you might also love our DIY project making a garden water feature for less than $30!

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1 Comment

  1. Kellen March 30, 2021 at 6:25 am

    We are looking to do something very similar to you! I’m assuming you had to use a hammer drill to drive in masonry / concrete screws?

    Also, for follow-up articles, a cut list would be very helpful!


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