Most houseplants grow perfectly well with top watering, pouring water onto the soil surface until it drains from the base. Bottom watering, where you place the pot in a tray of water and allow the compost to absorb moisture from below, is not universally better. It is, however, significantly better for certain plant types and situations, including plants sensitive to wet foliage, plants in very dense or hydrophobic compost that has stopped absorbing water from the top, and plants that tend to develop crown rot from water collecting at the base of the leaves.
This guide explains how both methods work, which plants genuinely benefit from bottom watering, and when to use each approach.
How Bottom Watering Works
Bottom watering involves placing your pot, which must have drainage holes, in a tray, bowl, or basin filled with 3 to 5 cm of water. The compost absorbs moisture upward through the drainage holes by capillary action. Leave the pot to soak for 20 to 45 minutes, then remove it, allow any excess water to drain from the holes, and return it to its position. Never leave a pot sitting in water indefinitely, prolonged submersion deprives roots of oxygen.
The key advantage of bottom watering is that it ensures the entire root zone receives moisture, including the lower compost that is often still dry after a light top watering. It also keeps the soil surface drier, which can help prevent fungus gnat infestations, as gnat larvae need moisture in the top few centimetres of compost to survive.
The main disadvantage is that bottom watering does not flush salts and mineral deposits from the compost. Fertiliser salts and hard water minerals accumulate in the compost over time. With exclusively bottom watering, these cannot be flushed downward and out through the drainage holes. Plants that are exclusively bottom watered should be top watered thoroughly once every six to eight weeks to flush accumulated minerals.
Which Plants Benefit Most From Bottom Watering
Several houseplant types benefit noticeably from bottom watering over top watering.
African Violets (Saintpaulia): Water on the leaves or crown causes brown spotting and rot. Bottom watering is the standard method for African Violets for this reason.
Plants with crown rot sensitivity: Cyclamen, Begonias, and some Bromeliads are prone to rot if water sits at the base of the leaves or in the crown. Bottom watering avoids this entirely.
Plants in very dense or compacted compost: If compost has become hydrophobic, water runs straight off the surface or around the edge of the pot without absorbing. Bottom watering forces moisture into the root zone from below. For severely hydrophobic compost, a thorough bottom soak combined with repotting into fresh mix is the most effective solution.
Succulents and cacti in shallow trays: Bottom watering is well-suited to shallow-rooted succulents in small pots that dry out very quickly. The soak method ensures the entire root mass gets moisture before the next watering cycle.
Orchids in bark: Orchids can be effectively watered by soaking the pot in water for 10 to 15 minutes to allow the bark to fully absorb. This is a form of bottom-and-side watering that ensures even moisture distribution through a medium that does not absorb water instantly. See our detailed guide to how to water an orchid.
When Top Watering Is Better
Top watering is adequate for the vast majority of houseplants, including Monsteras, Pothos, Philodendrons, Calatheas, Ferns, and most tropical foliage plants. It is faster, requires less setup, and, critically, flushes accumulated salts and minerals from the compost as the water percolates through and out of the drainage holes.
Top watering is also better for detecting how the compost drains. If water runs straight through without absorbing, the compost may be hydrophobic or the root system is so congested that water is bypassing it. These are useful signals that you would not detect with bottom watering alone.
For plants that dry out evenly and consistently, top watering done thoroughly, watering until it flows freely from the drainage holes, is equally effective to bottom watering and far less time-consuming for a large collection.
Semi-Hydro as an Alternative to Both Methods
Semi-hydroponics is a third approach that sidesteps the top versus bottom watering debate entirely. The plant grows in a mineral substrate, typically expanded clay pebbles (LECA), in a pot with a reservoir at the base. The plant draws water from the reservoir as needed, self-regulating its moisture intake.
Semi-hydro works well for Pothos, Monsteras, orchids, and many aroids. It dramatically reduces the risk of both overwatering and underwatering, and produces fast root growth once the plant has adapted to the system. The main adjustment period is two to four weeks while the plant transitions from soil to mineral substrate.
How to Top Water Houseplants Correctly
The most common top-watering mistake is giving a small amount of water, enough to wet the surface but not the entire root zone. This encourages shallow root development and leaves the lower compost permanently dry. Correct top watering means: pour water slowly around the base of the plant, not directly onto the centre, and continue until it flows freely and consistently from the drainage holes. Then stop, allow it to drain fully, and only return the pot to its saucer when no more water is running out.
Never leave the pot sitting in a saucer of standing water for more than an hour. Standing water around the drainage holes deprives roots of oxygen and is one of the most common contributors to root rot. See our guide to how often to water houseplants for advice on judging when the plant actually needs water, regardless of method.