Beginner Plans for a Balcony Herb Wall with Stacked Planter Boxes

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A stacked herb wall lets you grow 12 to 18 herb plants in about 8 square feet of balcony floor space. This beginner plan uses three simple rectangular boxes stacked vertically on a freestanding ladder frame. No wall anchors, no miter cuts, and no dado joints. You can build it in a weekend with a drill and a handsaw, and take it apart when you move.

The whole structure is 30 inches wide, 18 inches deep at the base, and about 54 inches tall. Each planter box is 28 inches long x 7 inches wide x 6 inches deep inside. That depth is enough for basil, parsley, thyme, mint, and chives without wasting soil or making the boxes too heavy. A box this size holds about 0.65 cubic feet of potting mix when filled to 1 inch below the rim, which weighs roughly 30-35 pounds when wet. Three boxes plus frame and soil will total around 120-140 pounds, well within most balcony load limits, but check your building’s rules first.

Choosing Wood and Hardware

For an outdoor herb wall, wood choice matters more than joinery. You want rot resistance without having to apply chemical treatments that will sit next to edible plants.

For most beginners, cedar fence pickets are the best balance. They are cheap, sold at any home center as 6-foot 5/8″ x 5-1/2″ pickets, and you need only four of them for the three boxes. They are thin enough to keep weight down but thick enough to hold screws without pre-drilling every hole. If you use pine to save money, you must line the boxes and seal the outside with an exterior food-safe sealer, and expect to rebuild sooner.

Use 1-1/4″ exterior wood screws (star-drive coated or stainless). Drywall screws will rust, stain the wood, and snap under load. You will need about 80 screws total. Get a small box of 1 lb, which is more than enough.

Cut List

All cuts are straight 90-degree crosscuts. No angles.

For the three planter boxes (identical):

Each box needs: 2 long sides at 30″ (from 1×6 or 5/1/2″ picket), 2 short ends at 7″ (from same stock), 1 bottom from 3-4 slats at 28-1/2″ long with 1/4″ gaps for drainage. Cut the bottom slats narrow – rip a picket to 3-1/2″ wide if needed, or use 1×3 cedar.

For the A-frame ladder stand:

2 uprights at 54″ (1×3 cedar or 2×2), 6 cross supports at 28″ (1×3) – two per tier to cradle each box, 2 base stretchers at 18″ to connect the feet front-to-back. This A-frame leans at about 10-15 degrees so each tier gets sun and water drains without soaking the box below. If you want a vertical wall instead of a lean, cut the uprights at 60″ and add a top cap, but you will need to anchor it to prevent tipping.

Tools You Actually Need

You do not need a table saw or pocket hole jig for this. A basic cordless drill/driver kit, a handsaw or circular saw, a tape measure, a speed square, and 120-grit sandpaper will do it. A drill is non-negotiable – driving 80 screws by hand will split cedar. If you have a miter saw, it will make the cuts faster and straighter, but it is not required.

Add two clamps if you have them. They help hold the box sides while you drive screws, but you can also have a helper hold the pieces or use a corner of your balcony to brace against.

Step-by-Step Build

1. Cut and sand. Cut all pieces to length. Sand faces with 120-grit just enough to remove splinters. Do not round over edges heavily – you want flat glue-free joints for screws.

2. Assemble boxes. Form a rectangle with the long and short sides. The short ends sit between the long sides. Drive two screws per corner. Keep the top edges flush. Check for square by measuring diagonals – they should be within 1/8″. If not, rack the box until they match before adding the bottom.

3. Attach the slatted bottom. Lay the bottom slats across the underside with a 1/4″ gap between each slat. A scrap piece of 1/4″ plywood makes a perfect spacer. Each slat gets one screw into each long side. The gaps are your drainage; without them soil stays soggy and roots rot in 48 hours. Do not add a solid plywood bottom.

4. Build the ladder frame. Lay the two 54″ uprights on the ground parallel, 28″ apart. Mark lines at 8″, 24″, and 40″ from the bottom. At each mark, screw a 28″ cross support between the uprights. Add the second cross support 6″ behind the first at each tier if you are building the leaning version – this creates a shelf. The bottom tier should be at least 8″ off the balcony floor to improve airflow and keep the wood out of standing water.

5. Set the boxes. The boxes just sit on the cross supports, not screwed down. This lets you lift them off to replant, clean, or move. If your balcony is windy above the 5th floor, add one screw through the box side into the cross support per side to prevent sliding. In high wind, a full wet box will not blow off, but an empty one will.

Drainage, Lining, and Soil

Failure mode number one for stacked walls is water damage to the balcony and to the wood. Do not skip drainage.

Staple landscape fabric inside each box to keep soil from washing out the slat gaps. Do not use plastic sheeting – it traps water. The fabric lets water through while holding soil. Add 1 inch of coarse perlite or small gravel at the bottom if you tend to overwater, but it is not mandatory if your gaps are clear.

Fill with container potting mix, not garden soil. Garden soil compacts and weighs 2x more when wet. Potting mix drains correctly and keeps total weight predictable. Fill to 1 inch below the rim so water does not overflow onto the box below and wash soil away.

Place a plastic boot tray or shallow storage lid under the entire frame on the balcony floor. It will catch fine runoff and protect decking. Empty it after heavy rain.

Finishing and Placement

Leave cedar unfinished if you like the silvered look – it will weather to gray in one season and still last 4-6 years. If you want color, use an exterior penetrating oil rated food-safe once cured, like linseed-based deck oil, on the outside only. Do not paint the inside of herb boxes; paint will peel into the soil.

Place the herb wall where it gets at least 4-6 hours of sun. South or west-facing is ideal. Put taller herbs like basil and parsley on the top tier, trailing thyme and oregano on the middle, and mint on the bottom. Keep mint in its own box – it will overrun everything if you mix it.

For watering, bottom-up is more forgiving. Water each box until you see drips from the slats, then stop. In summer heat, 7-inch deep boxes dry out in 24-36 hours, so check daily. A simple moisture meter is more reliable than the finger test in a deep box.

Common Mistakes to Avoid

Building boxes deeper than 8 inches seems better for roots but adds 15-20 pounds per box when wet and makes the whole wall top-heavy. Using solid bottoms with drilled holes instead of slats clogs within weeks. And crowding more than 4-5 plants per 28-inch box reduces airflow and invites powdery mildew – give basil 8 inches of spacing, thyme 6 inches.

If a box starts to bow outward after a season, add a small 1×2 cleat across the center bottom. Cedar pickets are thin and will bow under sustained wet soil load without it. That is a 5-minute fix that doubles box life.