Planter Saucers and Drainage: Keep Water Off the Balcony Floor
Drainage holes, saucer sizing, pot feet and emptying routines that keep runoff off your balcony floor, off the neighbor below and away from mosquitoes.
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Good planter drainage on a balcony takes three things: a drainage hole in the pot, a detachable saucer wider than the pot’s base, and the habit of emptying it. Pot feet or bricks lift a pot so it drains freely. Empty standing water at least once a week, which the CDC advises to stop mosquitoes breeding.
Drips from above usually come from hanging baskets, covered in coco liners for hanging baskets. Pots that hold their own water are in self-watering planters, clay pots in ceramic and terracotta planters, and the full range on the balcony planters hub.
Why balcony pots need drainage holes
A drainage hole lets extra water leave the pot so the roots get air. University of Illinois Extension calls a hole in the bottom critical, because waterlogged mix has little room for air and invites root rot. If a pot has no hole, Illinois says to make one, for example by drilling. University of Maryland Extension says all containers need holes or slits to drain, and that more holes can be added depending on the material.
Skip the layer of gravel. Illinois calls gravel in the pot bottom a myth: water perches in the mix above it until the mix is saturated. UMD says rocks, gravel or broken shards can raise the water table and waterlog the mix. Its one exception is weight to steady a light pot that tips over.
For a decorative pot with no hole, Illinois suggests double potting: grow the plant in a liner pot with holes, set inside the decorative one. Check that the inner pot never stands in water, and lift it out to drain the outer pot when water collects.
Saucers, trays and pot feet compared
| Option | What it does | Watch for |
|---|---|---|
| Detachable saucer | Catches runoff under one pot; easier to empty than one fused to the pot (UMD) | Standing water left after watering |
| Attached saucer | Catches runoff but stays on the pot | Hard or impossible to empty, which can waterlog roots (Illinois) |
| Large tray | Catches runoff from several small pots or a grow bag | Weight when full; empty it like a saucer |
| Pot feet or bricks | Raise a pot so it drains freely (UMD) | On their own, runoff reaches the floor |
| Self-watering planter | Holds water in a built-in reservoir | Check where it overflows when overfilled or after rain |
UMD says drained water can stain concrete and wood decking, and that saucers help when you garden above a neighbor’s balcony. Pot feet help drainage, but by themselves they let the runoff onto the floor. On a balcony, set pots on feet inside a wide tray, or use feet only where runoff goes to a drain on your side.
Self-watering planters with a built-in reservoir
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What size saucer does a planter need?
A saucer should be wider than the base of the pot, not the rim, with enough room around it to catch water running down the outside. Depth matters as much as width. Water the pot once the way you normally would, and see whether the saucer overflows. If it does, move up a size or water more slowly.
Measure tapered pots at the bottom. A pot that is narrow at the base and wide at the top needs a smaller saucer than the rim suggests, while a straight-sided pot needs one about as wide as the rim. Grow bags drain through their fabric sides as well as the base, so give them a tray wider than the bag.
Choose a saucer you can lift. A full saucer under a large pot is awkward to empty, and a turkey baster or small sponge helps draw the water out without moving the pot.
How do you stop water dripping on the balcony below?
Water that reaches the balcony below usually comes from overfull saucers, hanging baskets or rail planters, so deal with each one.
- Water slowly. Stop when water first appears in the saucer instead of filling the saucer to the rim.
- Hanging baskets drain straight down. Iowa State University Extension says to water baskets until water runs out the bottom, so hang them where that water lands on your own floor, or water them over a tray.
- Rail planters can drain over the edge. Check where the drain holes sit before you hang a box on the outside of the rail; see railing planters.
A watering can with a long, narrow spout makes slow watering easier than a hose. For how often to water, see watering a balcony garden.
Watering cans for slow, even watering
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Emptying saucers to stop mosquitoes and rot
A simple saucer routine
- After watering or rain: tip out standing water. UMD says water left in saucers can cause root rot or breed mosquitoes.
- Once a week: the CDC advises emptying and scrubbing, turning over, covering or throwing out items that hold water, and it names flowerpot saucers.
- Before a hot spell: check every saucer and tray, including ones under pots you rarely water.
Full saucers and trays also add weight on top of the wet mix in each pot. If you are adding trays under a row of large containers, balcony weight limits explains how to add up the load and who to ask about it.
Frequently asked questions
Do balcony planters need saucers?
On most balconies, yes. University of Maryland Extension says water draining from pots can stain concrete and wood decking, that saucers avoid this, and that they help when you garden above a neighbor's balcony.
How often should I empty plant saucers?
Empty them whenever water stands in them after watering or rain. University of Maryland Extension says to empty saucers regularly so water does not cause root rot or breed mosquitoes, and the CDC advises emptying and scrubbing flowerpot saucers once a week.
Is it OK to use a pot without drainage holes?
Not for planting directly. University of Illinois Extension says a hole in the bottom is critical so roots get air, and suggests drilling one or growing the plant in a liner pot set inside the decorative one.
Does gravel in the bottom of a pot help drainage?
No. University of Illinois Extension calls it a myth, and University of Maryland Extension says gravel or pot shards can leave the mix above them waterlogged.
Sources
- Container Drainage OptionsUniversity of Illinois Extension
- Growing Vegetables in Containers and Salad TablesUniversity of Maryland Extension
- Preventing Mosquito BitesCenters for Disease Control and Prevention
- Creating and Growing Hanging BasketsIowa State University Extension and Outreach
Filed under Balcony Planters: Which Container Fits Each Spot.
