Short answer: heavier than most people expect, and definitely not something you should carry up four flights while filled. A typical medium urban planter box, about 2 cubic feet, will weigh roughly 75–130 pounds when filled with moist potting mix. A large box—say 4 feet by 2 feet by 1 foot, or 8 cubic feet—can easily weigh 300–470 pounds or more. If it is filled with garden soil instead of lightweight potting mix, it can reach 600–900 pounds.
The math is simple. Total weight = empty container + soil + water + plants + any saucer or trellis. Soil weight depends on volume and moisture. Dry potting mix usually weighs 20–30 pounds per cubic foot. Moist potting mix is often 30–45 pounds per cubic foot. Saturated potting mix can be 50–60 pounds per cubic foot. Real garden soil or topsoil is much denser: about 75–100 pounds per cubic foot. Compost is around 40–50 pounds per cubic foot. Water adds about 8.34 pounds per gallon, so after rain or deep watering, a planter can gain a surprising amount of weight.
Container material matters too. A plastic or resin planter might add 5–20 pounds. A wooden or composite box might add 15–40 pounds. Ceramic, terracotta, concrete, or fiberstone planters can add 30–100 pounds or more before soil. Plants, trellises, and saucers add another 5–20 pounds. So for a fourth-floor walk-up, the filled weight is the number to plan around, but the empty weight and soil bags are what you actually carry.
Some examples:
- Small 18" x 12" x 12" box: about 1.5 cubic feet. Moist potting mix weighs 45–68 pounds; plus container and plants, total 60–95 pounds.
- Medium 24" x 12" x 12" box: about 2 cubic feet. Soil weighs 60–90 pounds; total 75–130 pounds.
- Large 36" x 18" x 18" box: about 6.75 cubic feet. Soil weighs 200–300 pounds; total 230–380 pounds.
- Raised bed 48" x 24" x 12": about 8 cubic feet. Soil weighs 240–360 pounds; total 285–470 pounds with a light container, and much more with dense soil or a heavy box.
For a fourth-floor walk-up, do not try to carry a filled planter upstairs. Carry the empty container, bags of potting mix, and plants separately. Fill and plant it on the balcony or landing. Use lightweight potting mix, not topsoil or heavy garden soil. Consider perlite, coco coir, or rice hulls to reduce density. Choose resin, plastic, fabric, or lightweight composite containers over ceramic or concrete. Use several smaller planters instead of one giant box, and distribute them near load-bearing areas if your building allows. Check with your building manager or a structural engineer about balcony load limits. And remember: water is heavy, so a planter that is easy to move when dry can become a two-person problem after a rainy week.
If you must move a filled planter, empty it into buckets first. That turns one impossible lift into several manageable trips. Your back, your stairs, and your neighbors will thank you.