DIY modern planter box

Planter boxes are one of the easiest ways to upgrade any space in your yard, including your entryway, or in this case in front of a backyard shed! We have been wanting something pretty to put in front of our shed since we finished it, but couldn’t lock down an exact design idea. After going back and forth on a few different looks, we settled on a DIY cinderblock planter box.

In case you missed our DIY shed build, click the buttons below to check them out! We are planning on doing a final reveal of the entire build once we wrap up a couple organization projects on the inside of the shed! So stay tuned for that!

So let’s get back to our DIY modern planter box. We decided that a cinderblock finish would give us the modern touch we wanted with a side of practicality. We didn’t like the idea of using wood, and then replacing a few years down the road, even if it was treated wood. It was also too farmhouse for our personal design taste.

This DIY project was specific to our space, so we’re going to share all the materials we used to make it, along with our favorite products that brought this diy planter box vision to life!


Depending on where you plan on creating your DIY planter box, will determine if you have to worry about making it level. The front of our shed wasn’t level so we had to account for that. The first thing we did is stake a scrap 1×2 into the ground where we wanted the first cinderblock to sit. If you don’t have to worry about this step, your planter box project will go super fast!

Once we lined the first cinderblock up with the back 1×2 stake, we could then place the second cinderblock and next 1×2 stake in the front of the planter box.

Once you have your two starting stakes properly secured in the ground, you’ll want to grab your string and tie it to each stake. You’ll then move to the other side of your planter box and repeat this step. When your string is nice and snug, grab your line level and make sure your lines are where they need to be. Make sure you measure the distance between where the BACK of your planter is going to sit and the front as well. That way your planter is the same width the entire way down! You don’t want a crooked planter box.

You’ll notice below that our string line in the FRONT of our planter box on the left side is way lower (touches the ground) than the string on the back right side. That’s because our ground was unlevel and we had to accommodate for that.

The next step when building our DIY modern planter box was the most time consuming and tedious part. We had to dig out alot of ground to make this entire project level. The tedious part is that our ground by the shed is hard, clay, roots, granite, and dry. We attempted to water it down with the hose, but that didn’t really alleviate any work, just made our workspace dirtier! 🙂

Below you’ll notice the blocks being semi buried to make the planter level. Continue adding your cinderblocks down your string line, making sure the line sits right at the top of each cinderblock.

Here’s a better visual for how your cinderblocks should line up with your string line! (If you’re having to accommodate for that!)

Once you finish your front line you can start the back of your planter box, but repeating the same steps. Line your cinderblocks up with your string line, and if the line doesn’t sit level with the top of your cinderblock, simply grab your shovel and dig some dirt out.

In the photo below you’ll notice that our front cinderblock stops at that random 1×2 stake in the middle. This is where our cinderblocks were level with the ground so after this one we could place the cinderblocks on the ground without removing any dirt.

Here’s a visual of the back of our planter box when it became level with the ground and we no longer had to remove dirt.

Next we started stacking our cinderblocks on the second row.

We were too impatient so wait, so we went ahead and added a cap block on the top so we could get a small glimpse of what it would look like when it was all put together!

Also, don’t worry we flipped that end cinderblock around before securing it for the final planter box. This was just a dry fit.

Here’s how all the cinderblocks looked in the dry fit prior to securing them together.

Now it’s time to get into the fun part, securing all of the cinderblocks so they don’t move! We did this using this adhesive. You’ll want to apply your adhesive around the perimeter of each cinderblock. Once your adhesive is on simply insert your cinderblock and gently apply pressure.


Now for the fun part, the finishing touches! We had our modern look with the cinderblocks, now we wanted a contrasting color that would pop against the shed. We highly, HIGHLY recommend using this paint product when working with exterior cinderblocks. We went with the shade “slate”.

We used this paint for our cinderblocks. It’s TEXTURED deck paint and it was the perfect match for the texture of the cinderblocks. I want to share how we applied it and what worked for us!

First you’ll want to grab your cheap paintbrush and go around and paint all of your seams. Allow these to dry, don’t worry it dries REALLY fast especially if you’re painting on a warmer day.

After we finished painting all the seams, Scot followed me with the textured roller as I painted each block with my brush. So I painted the cinderblock with the brush, and then as soon as I did he would simply roll over the cinderblock so that we had the texture and not the brush strokes.

Here’s how it looked once we were finished painting it.

Here’s where ALL of the hardwork came in. We moved approximately 50 5 gallon buckets of fill dirt into our new DIY modern planter box where the kids DIY playset used to be. Once it was filled, we broke up the bigger chunks and raked it level.

Last but not least, we planted our plants and gave them a nice bath!

Now for the gorgeous after photos! ENJOY!

Thanks for much for stopping by and checking out our DIY modern planter box. Make sure you’re following us on Instagram and Pinterest, where we share behind the scenes and DIY projects! Feel free to pin the graphics below to your boards to save this project for later!

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