Wall Flower Pot

Dimensions

Cut list

Tools you'll need

• ✓

  Measuring Tape (5m or longer)

  Used for measuring each component.

• ✓

  Pencil and Carpenter's Square

  Used for marking lines and confirming right angles.

• ✓

  Saw

  Recommended to use home center cutting service.

• ✓

  Electric Driver

  An impact driver increases work efficiency.

• ✓

  Sandpaper

  Prepare two types: #120 and #240.

• ✓

  Level

  Essential for checking horizontal alignment during assembly.

• ✓

  Clamps (2 or more)

  Used for temporary fixation during joining.

• ✓

  Brush and Paint Tray

  Used for applying wood preservative.

Materials

Build steps

1. 1

   Measure and Confirm Installation Location

   ≈ 15 min

   Measure the installation location of the wall flower pot (400×200×200mm). Check the window frame size, water splash path during watering, and sunlight exposure (southeast facing is ideal).

   Measure

   W 400 mm

   MeasureSTEP 1 / 10

   Tip

   • Set the box width 50mm smaller than the window frame for easier installation.
   • Design with a 20-30mm gap from the wall to prevent wall and window dirt from drainage after watering.
   • If attaching to a balcony railing, measure the railing width beforehand.

   Watch out

   • Measure the inner dimension of the window frame, not the outer. Overlooking frame thickness will cause fitting issues.
   • Plants will not grow well in north-facing locations with poor sunlight. Confirm the sunlight duration at the installation site.
2. 2

   Cut and Prepare Materials

   ≈ 20 min

   Cut SPF 1×6 lumber (12×140mm) into front and back boards (12×140×400mm) × 2, side boards (12×140×200mm) × 2, and bottom boards (12×140×376mm) × 2. Prepare 30 coarse-thread screws 38mm. Also prepare one can of water-based wood preservative for outdoor use.

   Cut

   Use the in-store cut service

   CutSTEP 2 / 10

   Tip

   • SPF lumber is thin and may warp considerably; confirm the board is straight by looking from the end when purchasing.
   • Bottom boards are 776mm long × 2, matching the inner dimension of 800mm front and back boards at 776mm.
   • Using a home center cutting service ensures accuracy. Cost is 30-50 yen per cut.

   Watch out

   • Thin boards split easily if screws are driven without pilot holes.
   • If stainless steel screws are not chosen, iron screws will rust within a year in outdoor environments.
3. 3

   Sanding

   ≈ 25 min

   Sand all components in order with #120 then #240 sandpaper. Since plants will be planted, carefully chamfer the inner corners to avoid injuring roots. Pay special attention to sanding end grain as it absorbs water easily.

   Sand

   #120

   SandSTEP 3 / 10

   Tip

   • End grains expose fibers and are water entry points; sealing these well with preservative is key to durability.
   • Sand both outer and inner surfaces thoroughly to prevent roots from snagging.
   • Chamfering edges protects plants from injury.

   Watch out

   • Avoid bringing sanding dust indoors; perform sanding outdoors.
   • Painting over leftover sanding dust produces rough finish.
4. 4

   Assemble Front, Back, and Side Boards

   ≈ 30 min

   Attach side boards inside both ends of the front and back boards. Lightly apply wood glue to the end grain surfaces, then drill φ3mm pilot holes from the front and back boards and drive 38mm coarse-thread screws twice at each joint (4 points × 2 screws = 8 screws total). Confirm right angles at the four corners using a carpenter's square while proceeding.

   Build the frame

   Tighten joints firmly

   AssembleSTEP 4 / 10

   Tip

   • The 12mm thickness of 1×6 lumber and 38mm screw length is appropriate, considering bottom boards and glue thickness (12+12 plus glue).
   • Pilot holes are mandatory; 12mm thickness boards split easily without them.
   • Quickly wipe off excess glue with a damp cloth.

   Watch out

   • Driving 38mm screws without pilot holes splits the 12mm thick boards.
   • Excessive glue that oozes inside prevents paint adhesion.
5. 5

   Attach Bottom Boards and Process Drainage Holes

   ≈ 25 min

   Place two bottom boards (140×776mm) side by side inside the box body, leaving a 5mm gap between them for better drainage. Drill four to six 8mm diameter drainage holes in the center of the boards to allow excess water to exit. Drill pilot holes and secure each board to the side and front/back boards with 38mm coarse-thread screws, two screws at each point.

   Drill a hole

   下穴 φ3.5mm

   DrillSTEP 5 / 10

   Tip

   • Drainage holes are essential; without them, soil becomes waterlogged causing root rot.
   • A 5mm gap between bottom boards improves drainage; use chopsticks to fix evenly.
   • Laying lightweight pumice on the bottom board prevents drainage holes from clogging.

   Watch out

   • Forgetting to drill drainage holes will kill plants.
   • Sealing bottom boards completely without gaps traps moisture causing wood rot.
6. 6

   Confirm Right Angles and Prepare for Painting

   ≈ 15 min

   Measure the two diagonal lengths of the assembled box with a tape measure and ensure the difference is within 2mm. Correct any deviations using clamps. Then, lightly sand the whole surface with #240 sandpaper and remove dust.

   Inspect

   No wobble ✓

   InspectSTEP 6 / 10

   Tip

   • A large diagonal difference may prevent the flower pot from fitting; target within 2mm difference.
   • Glue spots repel paint; sanding these areas is necessary.
   • Carefully treat the inner surfaces as well.

   Watch out

   • Ignoring warping leads to poor fit in the window frame.
   • Applying paint over dust results in rough surface texture.
7. 7

   Apply Outdoor Wood Preservative (First Coat)

   ≈ 30 min

   Apply a water-based outdoor wood preservative (such as Xyladecor or Osmo Color) with a brush to all surfaces (front, back, sides, and end grains). Apply extra preservative on the end grains to soak thoroughly. Let dry naturally for 2-3 hours.

   Paint

   Watco oil / varnish

   PaintSTEP 7 / 10

   Tip

   • Penetration into end grains is decisive for preservative effect; focus on these areas.
   • Water-based preservatives can be cleaned from brushes with water, making them beginner-friendly.
   • Coating inner surfaces protects wood from moisture in plant soil.

   Watch out

   • Thick coating causes uneven drying and later peeling; apply thin coats twice.
   • Do not paint if rain is forecasted before drying as the coating will wash away.
8. 8

   Second Coat Application

   ≈ 30 min

   After the first coat dries, lightly sand with #400 sandpaper then apply a second coat thinner than the first. Proper film formation is crucial for outdoor use. Let dry completely for at least 24 hours.

   Paint

   Watco oil / varnish

   PaintSTEP 8 / 10

   Tip

   • Two coats significantly improve protection; mandatory for outdoor use.
   • Sanding between coats with #400 sandpaper requires very light strokes to smooth fuzz.
   • Keep drying area dust-free.

   Watch out

   • Exposure to rain before drying ruins the coating; observe 24-hour drying.
   • Sanding too hard will peel off the first coat's film.
9. 9

   Attach to Window Frame

   ≈ 30 min

   Fix the box to the window frame using L-brackets or dedicated brackets. Secure brackets firmly to solid backing (wood framing or studs). After installation, gently shake the box to check for any looseness.

   Fix to the wall

   Anchor to studs

   InstallSTEP 9 / 10

   Tip

   • An empty box is lightweight, but soil, water, and plants weigh 10kg or more; use strong brackets.
   • Use a stud finder to locate framing before driving screws.
   • Removable hanging methods exist for easier watering and cleaning.

   Watch out

   • Exceeding bracket load capacity causes falling accidents; calculate total weight including fully loaded box.
   • Gypsum board alone cannot hold screws; always fasten into framing.
10. 10

    Planting and Final Checks

    ≈ 25 min

    Line the interior with a root barrier sheet or nonwoven fabric to prevent direct contact between soil and wood. Spread a 2cm layer of pumice, then add soil and plants. Water sufficiently and confirm drain water flows from holes. Monitor the plant condition daily for several days after installation.

    Done!

    Done — nice work!

    DoneSTEP 10 / 10

    Tip

    • Root barrier sheet extends wood life by 3-5 years and is available cheaply.
    • Pumice prevents drainage holes from clogging.
    • Initial watering should be generous to confirm proper drainage.

    Watch out

    • Without root barrier, wood corrodes due to soil moisture.
    • Water dripping underneath can stain surfaces; use a drainage catch to protect walls.

Warnings

• ⚠️Wood preservative treatment is essential for outdoor use (recommend reapplication once a year).
• ⚠️Use stainless steel screws (iron screws will rust).
• ⚠️Drill pilot holes before screwing to prevent wood splitting.

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