Bottom watering means the pot sits in a basin of water and the soil pulls the water up through the drainage holes. The roots get a full drink. The surface of the soil stays drier than it does with top watering.
It is a simple method. It needs a pot with drainage holes, a sink or tub, and about half an hour.
What you need
A pot with drainage holes. Bottom watering does not work without them.
A sink, bathtub, bucket, or deep tray. It must be wide enough to hold the pot and deep enough for a few inches of water.
Room temperature water. Cold water can shock tropical roots. Hot water can damage them.
How to bottom water, step by step
1. Check the soil first. Push a finger two inches into the soil. Water when it feels dry at that depth. A dry pot also feels light when you lift it. If you are not sure whether the plant needs water at all, read how to tell if a houseplant is overwatered or underwatered.
2. Fill the basin. Add two to three inches of water. For a small pot, one or two inches is enough. The water should come up the side of the pot but stay below the rim.
3. Set the pot in the water. If the plant sits in a decorative pot with no holes, lift the plastic nursery pot out and water that. Do not leave the plant in the outer pot while you fill it.
4. Let it soak. Most pots take 10 to 30 minutes. Small pots with loose soil finish fast. Large pots with dense soil take longer. Touch the top of the soil now and then. When the surface feels damp, the soil has taken up enough water.
5. Let it drain. Lift the pot out and set it on a rack or in the empty sink. Wait 10 to 15 minutes while the extra water drips out.
6. Put the plant back. Place it in its saucer or decorative pot. Pour out any water that collects in the next hour.
Which plants do well with bottom watering
African violets. Water on the leaves and crown can cause spots and rot. Bottom watering keeps the foliage dry.
Plants with thick, crowded leaves. When leaves cover the soil, it is hard to aim a watering can. Bottom watering skips the problem.
Plants with soil that has pulled away from the pot. Dry potting mix, especially mix with a lot of peat, can shrink and repel water. Top water runs down the gap at the edge and out the bottom. The root ball stays dry. Bottom watering gives the whole mix time to soak.
Plants with fungus gnats. Gnats lay eggs in damp topsoil. A drier surface makes the pot less inviting to them. It will not clear an infestation by itself. Read how to get rid of fungus gnats in houseplants for the full plan.
Limits of bottom watering
Salts build up in the soil
Water moves up through the soil and evaporates at the surface. The minerals in tap water and fertilizer stay behind. Over many bottom waterings, they collect in the top layer. A white or yellow crust is the sign.
Water from the top every few months. Pour water through the pot until it runs freely from the drainage holes. This flushes the minerals out. Buildup is one cause of brown tips, covered in why are my houseplant leaf tips turning brown.
Roots need air
A pot left in water for hours keeps the soil soaked. Roots in soggy soil rot. Set a timer and take the pot out when the surface is damp.
Heavy pots are hard to move
A large floor plant in a ceramic pot may be too heavy to lift in and out of a tub. Water those from the top, slowly, until water runs from the bottom.
Cacti and succulents need a short soak
These plants store water and rot in wet soil. Soak them for a few minutes only. Let the soil dry out completely before the next watering.
Common mistakes
Soaking too long. More time in the water does not mean a healthier plant. Stop when the topsoil is damp.
Watering on a schedule. The plant’s need changes with light, season, and pot size. Check the soil each time.
Skipping the drain. A pot that goes straight from the basin to a saucer sits in a puddle. Drain it first.
Using a pot with no drainage holes. Water has no way to leave the soil, and the roots stay wet. Use a pot with holes, or keep the plant in a nursery pot inside the decorative one.
What if the soil will not take up water
Water should climb the soil within 10 to 15 minutes. If the surface stays dry after 30 minutes, the soil may be compacted, or the roots may fill the pot. Roots that circle the inside and push out of the drainage holes mean the plant needs more room. Follow how to repot a houseplant step by step and use fresh mix.