Garden Variety: Several ways to water your indoor plants
What is the best way to water an indoor plant? Like so many things in gardening, the answer depends on a variety of factors. The most common methods are top watering, bottom watering and immersion watering. They all have pros and cons, but each one has a place in indoor plant care.
Top watering is the traditional method for providing water to indoor plants. With this method, water is poured from a watering can or other container to the surface of the soil in which the plant grows. Water soaks through the soil profile like rain soaks into the soil in nature.
Bottom watering for indoor plants means pouring water into a saucer, bowl, tray or similar container and setting a plant, still in its pot, in the tray. The water soaks into the bottom layer of soil and wicks its way up through the plant’s roots.
The immersion method of plant watering is like bottom watering but characterized by deeper water. Immersion watering is most useful for plants whose soil has dried to the point of becoming hydrophobic, or repelling water.
Top watering is the easiest method and works for most indoor plants. Gardeners should always check the moisture below the soil surface using touch or a sensor rather than relying on the appearance of the soil surface or a schedule.
With top watering, overwatering and underwatering are more common, but they can be prevented or alleviated with attention to subsurface soil moisture, an understanding of each specific plant’s needs and consideration for the environment in which the plant is growing. For example, cacti and succulents that prefer arid conditions may only need water after extended periods, while some tropicals might need water daily and special conditions to retain humidity.
Bottom watering is useful for plants that dislike moisture on their leaves. Some gardeners believe that this method reduces the likelihood of overwatering because the soil acts as a sponge and only soaks up what it can hold. The danger lies in filling saucer or tray and leaving the plant with standing water for extended periods. Most indoor plants dislike constant saturation. For plants whose roots have reached the bottom of the container, having them sit in water this way can lead to root rot and other problems.
Plants that have been underwatered through top and bottom applications are good candidates for immersion watering. Overly dry potting soil is like a hard, dry sponge that takes time to re-wet. During immersion, potting soil can soak up water and rehydrate.
With bottom watering and immersion watering, empty any excess water from the saucer or tray as soon as the soil is hydrated. Allow any excess water to drain before putting the plant back, or dump the saucer or tray again as needed to prevent the plant from sitting in water for too long.
With any watering method, pay attention to the moisture below the soil surface, be aware of the plants’ specific needs and consider the growing conditions. Avoid watering on a schedule, and remember that overwatering is more common than underwatering.
— Jennifer Smith works in regulatory horticulture and has worked as a horticulturist for various government entities. She has experience in landscape design and maintenance and as an educator.