An acrylic planter box is asked to do two opposite things: hold water and soil permanently, and look like a clean architectural element. The joint sealing and the drainage detail decide which of those wins.
A workplace fit-out in Singapore installed 28 white acrylic planter modules on a 14 m green wall. Within four months, three had leaked onto the floor below and the client wanted the system redesigned.
Acrylic planter box sections and drainage
- Body: 6 mm white or black cast acrylic, 250 to 300 mm deep
- Reservoir: 40 mm water layer with a 10 mm overflow slot
- Separation: geotextile over a gravel drainage layer
- Mounting: bracket every 600 mm, load rated to the wet weight
The wet weight is the number nobody calculates. A 600 x 250 x 250 mm module holds around 30 litres of wet substrate, which is 30 kg plus the box. Two brackets, 600 mm apart, each carrying 15 kg, is a different fixing from a picture frame.
Sealing, algae and the wall behind
Acrylic joints for a planter need a structural seal, not a decorative one. Solvent welding alone is not watertight under head pressure over years; a two-part adhesive with a 5 mm bond plus a solvent weld is the belt-and-braces detail used on reservoir boxes.
Algae is a light problem. Clear sides let light into the substrate and the inner face turns green, which is visible through the panel. White, black or frosted sides block the light and keep the module looking clean.
The wall behind matters as much as the box. A plasterboard stud wall will not take 30 kg modules unless the brackets land on studs or a plywood sub-frame. On a masonry wall, mechanical anchors are straightforward.
On irrigation, drip lines into each module are the reliable option; a single header pipe with gravity feed scales badly as modules are added. Overflow must discharge to a drain, not down the wall face.
Where the planter is part of a fit-out with other clear acrylic elements, the acrylic sheet for furniture guide covers bonding and edge finish, and the cut-to-size service guide explains how module sizes are specified.
Send your wall dimensions, planting plan and irrigation type to oversales@rpplexiglass.com for a planter quote.
Frequently Asked Questions
What thickness acrylic for a planter box?
6 mm for boxes up to 300 mm deep and 600 mm wide, 8 mm to 10 mm for larger modules or where the box is a structural part of a green wall. Water weighs 1 kg per litre, so a 600 mm box can hold 30 kg.
Do acrylic planters need drainage?
Yes, unless they are sealed reservoir units. A 10 mm drainage layer plus an overflow at the high water mark is standard. A sealed box with no overflow becomes anaerobic and the plants fail within a season.
Why do clear acrylic planters go green?
Light plus nutrients in the substrate. Algae grows on the inner face wherever light reaches the soil. Coloured or frosted sides, or a black backing panel, remove the light and the problem disappears.