Balcony and Patio Planters: Size, Weight and Drainage

On a balcony or patio, three numbers decide whether a planter works: its footprint, its filled weight and where its water goes. Measure before you shop: the floor you can spare, door swings, the path to the railing, hours of sun, wind, and the distance to the nearest tap.

Size: start from the floor you can spare

Our stocked Rectangular Planter comes in 40 × 12 × 20 in and 40 × 12 × 30 in (length × width × height). The narrow footprint leaves most of a balcony free, and the taller size lifts planting toward a seated eye line and gives roots more depth.

If neither fits, made-to-order sizes are priced instantly at 16–228 in long, 12–72 in wide and 11–48 in high in 0.25 in steps; larger sizes are built on a written quote. For an instant estimate on your size: Price your sizes.

Leave room to reach every side for watering and pruning, and keep planters back from railing edges so nothing can be knocked or blown over.

Weight: the soil is the load

Aluminum keeps the empty planter light. Filled with wet soil, it is a different object:

• 40 × 12 × 20 in: about 25 lb empty; filled, 350–460 lb with lightweight rooftop mix (105–135 lb/ft²) and 565–700 lb with standard soil (170–210 lb/ft²).
• 40 × 12 × 30 in: about 35 lb empty; filled, 525–685 lb with lightweight rooftop mix (155–205 lb/ft²) and 850–1,050 lb with standard soil (255–315 lb/ft²).

Filled weights assume saturated media up to the rim, at published densities of 60–80 lb/ft³ for lightweight rooftop mix and 100–125 lb/ft³ for standard soil; the lb/ft² figure spreads the weight over the planter's footprint. They are planning estimates, not a structural rating. Your building's owner or engineer decides what a balcony can carry and where; they may ask you to keep heavy planters near the building wall rather than at the outer edge. Try your own size in the planter weight calculator.

Drainage: know where the water lands

Water that drains out of a planter lands on the deck under it, and on a balcony it can reach the unit below. Drain holes are an option on made-to-order sizes; hole count and spacing follow the chosen dimensions. Before you plant, decide where the water goes:

• a drip tray under the planter, emptied after heavy rain; we make an aluminum drip tray that can be quoted with a planter order;
• pads under the planter, so water runs to the deck drain instead of pooling beneath it;
• your strata or building rules on runoff and on what may sit on the membrane.

Standing water in trays breeds mosquitoes and stains decks. Damage from blocked drainage and standing water is also excluded from our warranty, so keep outlets clear.

Wind, sun and heat

Higher balconies get more wind, and tall plants in a tall planter catch it. Choose compact planting for exposed corners and keep loose items off railings. In full sun a dark finish runs hotter than a light one; stock planters come in Semi-Gloss Black and Semi-Gloss White. Water containers in sun and wind more often, and check the soil rather than the calendar.

Growing media

Use a container mix, not garden soil, which is heavier and drains poorly in a container. A lightweight mix cuts the load. Ask the supplier for the saturated weight: a dry bag tells you little about the weight on your deck after a week of rain.

Before you order

• Building or strata approval, if your building requires it.
• Allowable load and placement, from the building's owner or engineer.
• A drainage plan for every planter.
• Water within reach of a hose or watering can.
• A way to get the empty planter in: lift, stairs and door widths.

Ready to choose: Shop stock sizes, or Price your sizes for a custom size.