Wood DIY Deck Planter Box To Upgrade An Old Deck With Plants And Style

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We designed and built this wood DIY deck planter box to disguise the ugly, old edge of our deck and make the whole deck look bigger and feel safer. It worked really well – and only took an afternoon to build it! Keep reading to learn how to build a planter box for your deck with style and function and on a budget.

Do you have an old deck that could use some sprucing up to make it more attractive and functional? We’ve been doing just that.

When we bought our weekend place years ago (aka our Mobile Home Makeover), we knew the entire place, including the deck, needed a lot of work. We’ve done lots to the deck already – and each project makes the whole place look better and better:

First, we built a simple hot tub deck in an afternoon. It was a simple and affordable project to hold our fun, new hard sided portable hot tub.

Next, we built our DIY deck extension and added a wide solid place to BBQ and entertain.

And then, we figured out how to build a deck rail bench on an existing deck and made a cozy place to have meals and play games.

What remained to do was fixing up this eyesore…

The edge of this deck was ugly and wonky.

There was some janky-looking lattice covering up this even jankier deck construction.

We had our work cut out for us to make this old deck solid and handsome.

I knew just what I wanted to do!

Years ago we built this deck in our backyard. It’s low enough that it doesn’t require a railing, but I wanted to make it feel more safe and look more beautiful.

Wood DIY Deck Planter Box — We built this DIY wood planter around two sides of the deck and filled it with plants. It makes the deck feel huge and look fabulous!

(We used Lowes deck designer free software to design and build our materials list for this deck – free and highly recommended!)

DIY wood planter at deck edge — We did the very same look for this deck. The plants give so much life and beauty.

Plus the deck planter makes the whole thing feel so much bigger and safer.

Now when we have our morning coffee in the chair you see above – we don’t worry about tumbling off the side.

This is where Ed takes over to tell you how he fixed up the deck and built this awesome DIY wood planter!

How to Build a Wood DIY Deck Planter Box

Materials

4″X4″ Pressure Treated lumber – length TBD based on the size of your bed.
2″x6″ Pressure Treated lumber – length enough to cap the bed when completed
1″x6″ Pressure Treated fence boards – to wrap the completed box
Galvanized Spikes – I bought mine in 8″ and 6″ lengths
Various deck screws and galvanized nails
Landscape fabric weed barrier
Soil (and rocks, etc to fill)
Plants (in this case 5 hostas)

How to:

Start by clearing and levelling the space where the raised bed will go, as well as the deck you’re bordering if it needs any help.

Once filled, your new raised bed will be a very permanent fixture so do your under-deck maintenance now, while you still can.

If you’ve inherited a deck, you’ve likely inherited a problem or two.

As you can see this 4″x4″ is sitting on bare earth, which means it will rot. Not a great quality in a structural member. So our old deck needed some upkeep before anything else.

I had already worked on one end, jacking the deck carefully, cutting off the below-grade/beginning-to-rot end of this 4″x4″ and inserting it into a deck block.

I needed to do that with the middle post, too.

Our deck also sagged in the middle due to this middle post.

I wanted to level the deck as well as make sure the post was actually in a deck block versus – have I already mentioned this? – bare earth.

When jacking and levelling, go slowly. Only do one area at a time, and make sure everything else is secure and solid.

Also, check to make sure your levelling doesn’t accidentally mess with something else.

In our case, the mobile home door opens out, and onto this deck. If I jack too much, there is a chance that the door won’t open.

We are fixing other people’s mistakes here, so we had to split the difference between a perfectly level deck and a usable front door.

In the end, it worked out well.

That post was also not connected to the deck joists in a meaningful/safe way.

When I have a chance to make something not dangerous anymore, I try to take it.

In this case, it meant adding a carriage bolt through to make sure the post actually supported things, like, you know, the deck.

Your materials don’t have to be new and pretty for this first part of the DIY wood planter.

Our material came from an old deck that was in a bad location (a wet area of the property that floods each spring) and it was gradually rotting. (See above: built right on the bare ground)

While I wouldn’t build a house out of these salvaged 4″x4″s, they are perfect for the raised bed frame.

I loosely stacked them to get a sense of how it would all line up, any cuts I would have to make, and any levelling I would have to do.

With an idea for shape and size now sorted, I built each layer of the raised bed – predrilling the corners then spiking them together.

Our bed was small enough that I could build these separately, then carry them to their final location.

Here’s the final spike in the first layer.

Try and get everything as square as possible here, because next, we need to make them level and the ground is already uneven enough.

Here’s layer one in place, levelled with some rocks underneath them (all that ugly gets hidden later) and with a support section in the middle.

The weight of the soil pushing against the sides won’t be that great, but these points also give extra spots to nail the layers together with.

Take time to get this layer right. If you do it well, the rest is fast and easy.

And you just keep adding layers.

I predrilled and spiked them together in several spots, then I would choose different locations on the next layer to keep things secured all over.

Last layer. Now for the wrapping and the capping.

Cut each fence board to suit the spot it is going into. We used the same galvanized nails between the boards as we nailed them to the frame. This was to ensure we got the same small uniform space between them.

If the ground is perfectly level all the way around, you might be able to cut them all the same. Ours wasn’t.

Okay, bad bloggers: we didn’t take a photo of this, but before we filled the raised bed with soil, we lined it with landscape fabric to prevent the soil from escaping and reduce the chance of weeds getting in.

We also filled the bottom with some rocks from our forest so we didn’t need to buy quite as much soil to fill it.

The soil itself is a mix of topsoil and bagged composted manure. Starting to look finished here!

I trimmed the bed out with a picture frame border of 2″x6″ pressure treated.

Because my mitre saw can’t cut mitres this long, I had to scribe them and then cut them by hand with a circular saw.

Lastly, we rebuilt the not-great stairs with solid, fresh material. Because the raised bed itself is so solid and substantial, these new stairs won’t be going anywhere anytime soon.

Robin chose to fill the beds with 5 hosta plants. Mass plantings can be beautiful and easy to maintain. Our two goals for plants here.

The total cost for plants: $0!

If you’ve got a friend who gardens it may be worth asking them if they have any plants they need homes for. Our friend Judy gave us these from her beautiful yard! (Thanks again, Judy!)

Wood DIY Deck Planter Box How to build — Tadaa! Beauty!

Your eye is drawn to these lush green plants – instead of the formerly sad and wonky looking deck.

Diy deck planter outdoor — And here’s a straight-on look at this new area. I think you’ll agree this is a major improvement!

You can find all our DIY Deck Upgrade projects here.

Robin & Ed Hicken Creators

Robin and Ed are a DIY-loving couple with over 25 years of design and build experience. Also, Robin is a Nutritionist and former Registered Dietitian and Ed is an award-winning Business Educator. We share strategies for living a rich life on a DIY budget: creative money-savvy ideas for a stylish home, healthy meals and family fun. Our work has been published in the pages of Do It Yourself, Farmhouse Style and Better Homes & Gardens magazines.