What can I do with the planter box in my HDB flat?

HDB planter box: what is not allowed

The answer is no to anything that changes what the box is or closes it off. HDB's Important information on renovations page lists "change of use of planter box" as disallowed building work. It also disallows partial or total enclosure of a planter box, including solid metal external grilles, and permanently sealing a planter box. The aircon ledge falls under the same list: enclosing or grilling it, or changing its use, is disallowed too.

These lines rule out common ideas: capping the box with a slab for a kitchen shelf, boarding it in to hide clutter, or screeding it shut. Each one seals the box, encloses it or gives it a new use.

If a previous owner left work like this, or a contractor offers to "tidy up" the box during a kitchen job, read our guide to unauthorised renovation in HDB flats before you sign anything. Turning down a line item in a quotation is easier than removing finished work later.

Planter box renovation HDB rules for newer flats

Newer flats have a second set of limits. HDB's window works guidelines say that for flats under its newer window rules, where an open balcony or pure planter box is provided, windows, full-height sliding doors and glass panels are not allowed at the balcony or planter box. The same HDB page sets the cut-off for which flats these rules cover, so check your flat against it first.

This often comes up with new BTO owners who want to keep rain or road dust off their plants. A glass panel may look like a neat fix, but at a pure planter box under these rules you cannot have one.

You can still work inside the open box: choose pots that fit the depth, trim plants back from the edge and leave the opening clear. For frames, grilles and replacements elsewhere in the flat, see HDB window replacement rules.

Weight and drainage

Soil gets heavier when it is wet, and large glazed pots, a raised bed or a decorative water bowl add up quickly. Keep the load modest with lighter plastic or fibreglass pots, a lighter potting mix and fewer big containers. If you are not sure something is too heavy, ask HDB before you put it in.

Find the drain outlet before you place any pots, and space or raise them slightly so water can reach it. Soil, roots and fallen leaves creep in and slow it down. An hour or two after a heavy downpour, check the box. If water is still sitting there, the outlet needs clearing.

Water that cannot drain has to go somewhere. A damp patch, bubbling paint or a stain on the wall beside or below the box can point to seepage. Our guide to water seepage on the wall explains the signs.

Planter box mosquito checks

Pots, saucers and leaf litter give stagnant water plenty of small, hard-to-see places to collect.

NEA's dengue prevention measures ask you to remove water from plant pot plates every other day, and to change the water in vases and scrub the insides. In a planter box, that means lifting each pot and tipping out and wiping the saucer, not just glancing over the ledge. NEA also says not to place trays or containers under or on an aircon unit, as they can let mosquitoes breed. If you need a tray, NEA points to a patented air-conditioner tray and asks you to check it so the drain point does not choke and hold water.

Also check a cracked pot holding a puddle, a plastic bag caught behind a planter, an upturned lid and a leaf-clogged drain outlet.

For the rest of the flat, see how to prevent mosquito breeding at home.

Cleaning and pests

Dead flowers, dry leaves, litter dropped from upper floors and dust from corridor sweeping all settle in planter boxes. Once a week, put on gloves and scoop it out with a small dustpan. Bag the debris rather than hosing it towards the outlet, where it only causes a choke.

Pigeons perch among pots, nest in quiet corners and leave droppings that stain the box. Our guide to pigeon deterrents in HDB flats covers the options. Before you fit anything, make sure it would not enclose or seal the box.

Help with grilles or drains

A handyman can often clear a choked outlet, lift out heavy pots or reset loose drain gratings. If the choke keeps coming back, a licensed plumber can check the pipe beyond the outlet. Quotes depend on the job, so tell them the size of the box, how many pots it holds and where the water ends up.

If anyone suggests grilles, glass or a cover, stop and check the rules first. Our HDB balcony rules guide covers open spaces in the flat, and the renovation rules FAQ answers wider questions about what needs approval.

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