How to Build a Deep Planter Box for Flowers and Herbs

7 Materials
1 Day

We adopted a new dog, who we love and adore...but he’s a digger! So I had to find a new way to plant the herbs and flowers that I love so much in the summer. My problem was solved with this deep planter!

This post was sponsored by Gardena, however, all thoughts and opinions are my own.

I began by measuring out the space, and drawing a simple diagram to figure out how much wood I needed. (I used a scale of 1 in = 1 ft to keep it simple for myself). Since I needed to make this planter fairly tall, I opted to do 5 levels of deck planks, each of which are 5.5 inches tall, for a box that would be 27.5 inches tall when finished. You could make this taller or shorter if you wish.

Once I had my measurements, I cut the wood to size using my miter saw (though you could also use a circular saw, table saw, or even a jig saw).

I was lucky enough to find a large number of slightly irregular pressure-treated deck planks in the “cull wood” section of my local home improvement store for 70% off! (This was an amazing find given the price of wood these days!) Pressure treated lumber will last far longer than other types of wood, but you could also use cedar or redwood. Untreated pine, though the least costly, will degrade quickly, and you may only get a couple of years out of your planter.

NOTE: There is a lot of debate about whether pressure treated lumber is safe to use for raised planter beds, especially those that will contain edible plants. In the United States, pressure treating solutions used to contain Chromated Copper Arsenate (arsenic); if it were to leach into the soil, it could potentially make plants toxic. But in 2003, the Environmental Protection Agency banned the use of CCA, opting for safer compounds. So if you are in the United States, as long as your wood was treated after 2003, it is safe to use for planter boxes. If you are outside of the United States, check the regulations in your local area. 

Tall boxes will also need bracing pieces in the corners and along the long sides to secure the levels together. I repurposed some deck balusters that I had left over from my recent deck renovation. I cut them to a height of about 27 inches, then hammered them into the ground a couple of inches to hold them steady in place. (It is not necessary to sink them deeply or set in concrete.) I used the cut planks to measure the exact location for each brace.

I then began screwing in the planks along the sides using 2 in. exterior screws. (Be sure to use exterior screws, as they are more rust resistant.) Make each plank is level before screwing it in, and pre-drill your holes to prevent splitting the wood.

Once you get the first level screwed in all the way around, the rest go up very quickly.

Make sure to clear out any grass or weeds that might be at the bottom of your planter.

I lined the bottom and sides of the box with landscape fabric for two reasons:

  1. To minimize weed and grass growth
  2. To keep the soil from bleeding out of the sides

If you are concerned about the chemicals in the pressure treated lumber leaching into the soil, use sheets of plastic instead. 

The native soil where I live is primarily clay: nutrient-rich, but terrible for drainage. So I added gravel (repurposed from my old garden) to the bottom of the box to provide good drainage. This has the added bonus of helping to fill up the box. 

Since I really don’t need 27 inches of soil depth for anything I plan to grow, and dirt is NOT dirt cheap, I added some natural materials on top of the gravel to help fill in the space. I used scrap wood from my workshop (nothing pressure treated, stained, or painted -- just your basic pine, cedar, and poplar scraps), and some pine needles, leaves, and twigs from the woods behind my house. 

I topped all of that with some of the soil from the old garden, leaving me only about 8 inches of depth to fill with new soil. But before I did that, I covered the box with plastic for a few days to kill off any grass or weeds that might have been inadvertently transplanted from the old garden.

NOTE: During hard freezes, NEVER cover your plants with plastic sheets, unless you can ensure that the plastic does not touch the plant directly. The direct contact of the plastic will actually cause your plants to freeze even worse than if they had been left exposed. Use fabric sheets or fabric tarps instead.

While I waited for the plastic to do its job killing the weeds, I got to work installing my new Gardena Wall Mounted Retractable Hose. 

All hardware is included with the installation kit, and the instructions were simple! The only tools I needed were a drill with a 8 mm (or 5/16 in) bit, a 10 mm wrench/socket wrench, and a Phillip’s head screwdriver.

The Gardena Wall Mounted Retractable Hose, as its name implies, is intended to be mounted to the exterior wall of your home, near your garden spigot. This is necessary for stability of the retracting mechanism. (I actually attached mine to the fence post, which is adjacent to the house and faucet and sunk into concrete, so it was adequately stable.) 

First mark your holes using the reel base as a guide, making sure to keep the base level. (You can also measure the holes to mark them, but I find this method to be more accurate.)


NOTE: The Gardena Wall Mounted Retractable Hose Reel might arrive already attached to the base, but is easily removed by loosening the screw underneath.

Then pre-drill your holes using the 8mm (5/16 in) bit.

Then screw in the bolts using a 10mm wrench or socket wrench. (You could also use an adjustable wrench or impact wrench.)

If you plan to install the Gardena Wall Mounted Retractable Hose Reel directly to the house, the installation kit comes with anchors.

Once you have installed the three mounting screws, place the hose reel into the base. It slides right in!

Then tighten up the screw underneath to secure it tightly.

Attach the tap connector fitting to your spigot, and snap the leader hose into place. (These two may have arrived already attached, so you may need to separate them first just by firmly pulling them apart.)

And voila! The Gardena Wall Mounted Retractable Hose reel is installed!

After several days, I removed the plastic from the planter box and added in fresh new soil. I only had to purchase about 10 cubic feet of garden soil to fill the box up the rest of the way (plus one bag of composted manure for a little extra nutrient kick).

Finally time for the fun part! I love to have fresh herbs for the summer, so I planted basil, parsley and oregano, as well as some thyme and chives I salvaged from the old garden. But I wanted beauty also, so I added some butterfly-attracting flowers including salvia, marigold, petunia and zinnia.

Once the plants were in, it was time to water deep! Watering is so easy with my Gardena Wall-Mounted Retractable Hose Reel! With just a simple tug, it rolls itself up. No more hand-rolling the hose, or cranking the manual hose reel when you’re done. It’s so much easier to get out there in the morning before work and get everything watered without getting filthy or sweaty!

This post was sponsored by Gardena.

Watch the full video of this project on YouTube!

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4 of 5 comments
  • ChickFix ChickFix on Jun 15, 2021

    I'm not sure he would stick to just one area, simply because I built it for him 😅

    • See 1 previous
    • Erin Erin on Jun 16, 2021

      Pupperoni AKA Poodle Crack is a great training treat.

  • Margie Margie on Jul 15, 2021

    I too have doggie problems; not that they dig, but that they are not very "neighborly". My dogs & my neighbor's dogs are constantly barking & snarling at each other (w/ only the fence between them) and they have now worn out the grass along the fence (which turns to mud on rainy days😠). I now know how to obstruct their view of my neighbor's dogs, and make it look pretty at the same time🌺. Fortunately the grass is already worn out, so there's no need for me to dig it out!😄

    I can't believe I didn't think of this before😏 I will definitely try it🤞.