Plan your balcony
Dimensions and exposure. The walkway you keep clear decides how much is left.
How this planner works
- Planting area = balcony area − (length × walkway width). The walkway is kept clear along the full length.
- The planting area is split 50% large, 35% medium, 15% small, at 4, 2 and 0.8 sq ft of footprint per planter respectively.
- Railing boxes = floor(length ÷ spacing), and they sit outside the floor area entirely.
- Soil volume is estimated at 2 cu ft per large planter, 1 per medium, 0.3 per small and 0.8 per railing box.
- Wet weight = soil volume × 45 kg, then divided by the balcony area in square metres to give a loading figure.
- Daily water = soil volume × 0.14 litres in full sun, 0.09 in part sun, 0.05 in shade.
| Exposure | What grows | Daily water per cu ft of soil | Planter material |
|---|---|---|---|
| Full sun, 6+ hours | Bougainvillea, adenium, curry leaf, chilli, lemongrass | 0.14 litres | Terracotta or light-coloured — never black plastic |
| Part sun, 3–5 hours | Tulsi, mint, aloe, jasmine, peace lily | 0.09 litres | Anything; terracotta breathes best |
| Shade, under 3 hours | Snake plant, ZZ, monstera, philodendron, ferns | 0.05 litres | Glazed or plastic; drying is slower |
| Any | Soil weight wet | 45 kg per cu ft | — |
| Any | Drip line on a timer | ₹6,000 – 9,000 installed | Needs a tap point and a socket |
Design and build under one accountable roof
Worked example — an 8 × 4 ft balcony
| Step | Arithmetic | Result |
|---|---|---|
| Balcony area | 8 × 4 | 32 sq ft |
| Walkway kept clear | 8 × 2.5 | 20 sq ft |
| Planting area | 32 − 20 | 12 sq ft |
| Large planters | floor(12 × 0.5 ÷ 4) | 1 |
| Medium planters | floor(12 × 0.35 ÷ 2) | 2 |
| Small planters | floor(12 × 0.15 ÷ 0.8) | 2 |
| Railing boxes | floor(8 ÷ 1) | 8 |
| Soil volume | 2 + 2 + 0.6 + 6.4 | 11 cu ft |
| Wet weight | 11 × 45 | 495 kg |
| Daily water, part sun | 11 × 0.09 | 1 litre |
The three things that kill a Mumbai balcony garden
Water, in both directions. A full-sun balcony in April needs watering twice a day, and a week away in May will kill everything in a terracotta pot. A drip line on a timer costs ₹6,000 to ₹9,000 for a small balcony and is the single intervention that makes a balcony garden survive more than one summer. It needs a tap point and a socket, both of which are trivial to add during a renovation and awkward afterwards.
Waterproofing is the second. A planter standing directly on a balcony slab holds a permanent damp patch under it, and the membrane below fails there first — usually showing up as a stain on the ceiling of the flat below eighteen months later. Every planter should sit on feet, in a tray, or on a raised deck with air beneath. And the balcony drain must never be blocked by a pot, a deck or a layer of fallen leaves; in a Mumbai downpour a blocked balcony drain puts water into the living room within minutes.
Third is the society. Many Mumbai societies restrict what can be hung on the external face of a railing, and some prohibit it outright after a pot has fallen. Railing boxes should always be fixed on the inside face with a mechanical bracket, not balanced or hung on the outside. It is a five-minute decision that removes a genuine risk to somebody below.
Every constant on this page comes from Greenbox site records — measured drawings, signed BOQs and completion certificates from projects delivered between 2023 and 2026 — rounded to the figures an estimator would actually write down. We publish them so the arithmetic can be audited rather than trusted. Treat the output as a planning figure: accurate enough to brief a landlord, a bank or a family, and not accurate enough to sign a contract against.
What this tool does not cover
- Structural capacity. A cantilevered balcony has a live load limit, and a heavily planted balcony with a water feature can approach it — take a structural opinion above about 150 kg/m².
- Society rules on external planters, awnings and screens, which vary widely and are worth reading before buying anything.
- Waterproofing condition. If the balcony membrane is old, deal with that before laying a deck over it — see the waterproofing area calculator.
- Decking, pergolas and screens, which are joinery and priced separately.
- Wind. Above about the fifteenth floor in Mumbai, tall plants and light pots are a hazard rather than a garden.
- Plant cost, soil, and the ongoing replacement that any balcony garden involves.
Selected work by Greenbox Design Studio. Tap any image to enlarge.
Frequently asked questions
How much weight can a balcony take?+
A Mumbai balcony slab is typically designed for around 300 kg per square metre of live load, but a cantilevered balcony deserves care. Wet soil is 45 kg per cubic foot, so a heavily planted 32 sq ft balcony can reach 500 kg. Above about 150 kg/m² it is worth a structural opinion.
What plants work on a Mumbai balcony?+
In full sun: bougainvillea, adenium, curry leaf, chilli and lemongrass. In part sun: tulsi, mint, aloe, jasmine and peace lily. In shade: snake plant, ZZ, monstera and ferns. Matching the plant to the exposure matters far more than anything else you do.
Can I put a planter directly on the balcony floor?+
No. A pot standing on the slab holds a permanent damp patch under it and the waterproofing fails there first, showing as a stain on the neighbour's ceiling a year or two later. Use pot feet, a tray, or a raised deck with air beneath.
How much water does a balcony garden need?+
About 0.14 litres per cubic foot of soil per day in full sun, 0.09 in part sun and 0.05 in shade. In April and May a full-sun balcony needs watering twice a day, which is exactly when most balcony gardens die — a drip line on a timer solves it for ₹6,000 to ₹9,000.
Should railing planters hang inside or outside?+
Inside, always, on a mechanical bracket. A pot hung on the outside face of a railing above a Mumbai street is a genuine hazard, and many societies now prohibit it outright after an incident. The plants grow just as well on the inside face.