How much water should I give a plant?

Water slowly until a little drains from the bottom of the pot, which is roughly a quarter of the soil volume. Empty the saucer so roots do not sit in water.

How do I know when a plant needs water?

Push a finger about one inch into the soil. If it feels dry, it is time to water. Light pots and drooping leaves are other signs.

Is overwatering worse than underwatering?

For most houseplants, yes. Soggy soil starves roots of air and causes root rot, while a thirsty plant usually recovers quickly after a drink.

Do plants need less water in winter?

Yes. Shorter days and cooler rooms slow growth, so most plants need about half again as long between waterings in fall and winter.

Plant Watering Calculator

Get a starting watering schedule for your houseplants based on plant type, light, season and pot size, with an estimate of how much water to give each time.

Plant type

Light

Season

Pot diameter

A starting schedule only. Always check that the top inch of soil is dry before watering.

Water every

7 days

About 4.3 times a month

Each watering

Water amount: 2.2 cups
In fluid ounces: 18 fl oz
Approx. soil volume: 127 cu in

How to calculate plant watering

Pick the group that best matches your plant. Succulents and cacti store water in their leaves and prefer to dry out fully. Tropical plants such as pothos, monstera and philodendron like the top inch of soil to dry before watering. Ferns prefer soil that stays lightly moist, and herbs in small pots dry out fastest of all.
Light and season change how quickly a plant uses water. A plant in direct sun drinks faster than one in a dim corner, so the calculator shortens the interval for strong light and lengthens it for low light. In fall and winter most houseplants grow slowly and need about half again as long between drinks.
Pot size matters too. Small pots hold little soil and dry out quickly, while large pots stay damp longer. The calculator adjusts the interval for pot diameter and estimates the water per session as about a quarter of the soil volume, which is roughly enough to soak the root ball and let a little drain out the bottom.

Formula: days = round(base days × light factor × season factor × pot factor) soil volume = π × (diameter ÷ 2)² × diameter × 0.75 water per session = soil volume × 0.25

Formula

days = round(base days × light factor × season factor × pot factor) soil volume = π × (diameter ÷ 2)² × diameter × 0.75 water per session = soil volume × 0.25

Where:

base days: = Succulent 14, tropical 7, fern 4, herb 3
light factor: = Low 1.5, bright indirect 1, direct sun 0.75
season factor: = Spring and summer 1, fall and winter 1.5
pot factor: = Up to 4 in 0.8, up to 8 in 1, larger 1.25

Worked example

A tropical plant in bright indirect light during summer, growing in a 6 inch pot, uses 7 × 1 × 1 × 1 = 7 days, so water about once a week.

A succulent in low light during winter in a 10 inch pot uses 14 × 1.5 × 1.5 × 1.25 = 39.4, so roughly every 39 days, only after the soil is completely dry.

Simple habits for healthy houseplants

Use pots with drainage holes and a light, well draining potting mix suited to the plant. Water in the morning with room temperature water, soaking the soil evenly rather than splashing only one side. Group plants with similar needs together so one watering routine fits them all.

Treat any schedule as a starting point and adjust it by watching the plant. Yellow, soft leaves usually mean too much water, while crispy brown tips and curling leaves often mean too little. Repot when roots circle the bottom of the pot, and expect to water a little more often once the plant is in fresh soil and growing again.

Frequently asked questions

Most tropical houseplants need water about once a week in summer and every 10 to 14 days in winter. Succulents may only need water every two to four weeks.