When to water houseplants
Watering houseplants can be challenging due to the diverse needs of different plant varieties and the influence of factors such as soil type, indoor humidity, temperature, and sunlight intensity on soil moisture. A fixed watering schedule may not suit all plants. In this blog, I'd like to share my personal favorite method, along with two traditional methods that many gardeners use, to accurately determine when to water houseplants.
Regular observation is key to determining when to water your plants. Thirsty plants may display drooping leaves — a sign you will begin recognize with familiarity. By inspecting your houseplants daily, you can make informed watering decisions and detect early signs of other issues.
Determining When to Water: Two Reliable Tests
Two Inch Test
To assess soil moisture, insert your finger or a chopstick 2 inches deep into the soil. Water the plant if dry, wait if slightly damp, and avoid watering if wet. Use the dampness on your finger or chopstick as a guide.
A houseplant's weight can indicate its watering needs. Lift the pot to assess its heaviness. A well-watered pot feels heavier, while a dry pot feels lighter. By learning the weight difference, you can intuitively determine when to water the plant.
What is Top Watering?
Top watering, the practice of pouring water onto the soil's surface, is a standard method for watering houseplants. Let the soil dry completely between waterings, then water thoroughly until it drains from the container's bottom. For standard pots with saucers, empty any excess water from the saucers post-watering. (1)
Advantages and disadvantages of top watering
Top-watering, when done correctly, is a straightforward and efficient way to water plants. This practice is especially beneficial after fertilizing, as it flushes out excess salts and minerals, promoting overall plant health.
Plants with delicate foliage or stems are susceptible to damage from direct water contact during top watering, potentially leading to rot or fungal infections. Careless top watering also risks overwatering, which can cause root rot and related problems. Another challenge is uneven water distribution.
What is bottom watering?
Bottom watering is a technique for hydrating houseplants in which the pot's bottom is submerged in water, allowing the soil to absorb moisture through the drainage holes. This process occurs through capillary action, which naturally draws water upward into the soil.
Advantages and Disadvantages of Bottom Watering
Bottom watering directs water to the roots, safeguarding leaves and stems from water damage and reducing the likelihood of rot and fungal infections. By allowing soil to absorb only the necessary water, this method minimizes overwatering and prevents saturation. It also fosters deep root growth as roots seek water downward, contributing to a robust root system. Moreover, bottom watering ensures uniform moisture distribution in the soil—a key advantage for larger pots where even hydration is crucial.
A potential risk of bottom watering is overwatering if plants remain submerged too long. To avoid this, remove the plant when the soil's top layer becomes moist, signaling complete water absorption. Proper drainage is vital to prevent water pooling at the pot's bottom, which could cause root rot. Additionally, bottom watering may lead to mineral build-up in the soil, creating salt-like deposits on the surface, particularly if the water contains heavy mineral deposits. To mitigate this, occasionally use top watering to flush out accumulated minerals.
Plants that prefer bottom watering
Houseplants that prefer bottom-watering typcially have fragile leaves or sensitive stems which are prone to rot if they get wet.
Bottom watering is ideal for Tradescantia plants because it avoids getting water on their rot-prone leaves and stems.
African Violets prefer to be bottom watered because the crown and stems are susceptible to rot if they get wet.
Many carnivorous plants would prefer to be bottom watering because it avoids getting water on their sensitive leaves.
Can Humidity Water Plants?
Believe it or not, some plants have a remarkable ability to quench their thirst by absorbing moisture directly from the air! Humidity plays a key role in keeping many plants hydrated and can even help maintain soil moisture.
The easiest way to increase humidity, you can place the plant on a pebble tray filled with water or use a humidifier. Grouping your plants together can also help but be cautious of spreading pests or diseases!
But don't put away your watering can just yet! While humidity can be a helpful ally, most plants still rely on traditional watering to meet their hydration needs. And be mindful—too much of a good thing can be troublesome and excessive humidity may lead to the growth of unwanted fungi and bacteria.
Plants that love humidity
Orchids are epiphytes, which means they naturally grow on trees or other surfaces in their native habitats. In these environments, they are exposed to high humidity levels.
In their natural habitat, ferns often grow in shady areas where the air is moist and humid, such as in rainforests, and they require a consistent level of moisture in the air and soil to thrive.
Tillandsia, also known as air plants are epiphytes that grow without soil and absorb nutrients and moisture from the air. In their native habitats, air plants are often exposed to high humidity levels.
What is soilless gardening?
Soilless gardening methods allow plants to grow without the use of soil. Instead, plants are nurtured in a carefully balanced nutrient solution that supplies all the essential nutrients required for healthy growth. Along with providing the right nutrients, it's important to closely monitor the pH of the solution, ensuring it stays within the optimal range for plant development.
Advantages of Soilless Gardening
Soilless gardening has several advantages over soil-based gardening, such as water conservation, increased growth rate, better control over nutrient intake, fewer pest and disease problems, and no need for soil.
Plants that can grow soilless
Lucky bamboo is a plant that naturally grows in water, making it an excellent candidate for soilless growing which provides the plant with the consistent moisture and nutrients.
Soilless gardening provides basil with consistent moisture, nutrient delivery, oxygenation, and space optimization. These factors contribute to healthy growth and high yields of fresh, flavorful basil.
Spider plants produce baby plants or spiderettes on long stems. These spiderettes can be easily propagated by placing them in water or soil until they develop roots, and then potting them separately.
How to Grow Hydroponic
Select suitable plants: Choose houseplants that are compatible with soilless growing in water (hydroculture).
Fill with water: Add clean distilled or filtered water to the container, ensuring the water covers the plant's roots but doesn't submerge the stem or leaves. Avoid tap water, which may contain harmful chemicals.
Supply nutrients: Provide essential nutrients by adding hydroponic nutrient solutions or organic alternatives like seaweed extract to the water. Follow product instructions and monitor nutrient levels regularly.
Regular maintenance: Refresh the water every 2-4 weeks or as needed, maintaining a consistent water level. Replace water promptly if algae or contaminants are present.
(University of Minnesota Extension)
Water Quality: For hydroponic plants, use clean, filtered, or distilled water. Tap water may contain chlorine, fluoride, and minerals that can damage plants and cause mineral buildup on roots. Using filtered or distilled water mitigates these risks.
Nutrient Levels: Hydroponically grown plants don't receive nutrients from soil, so it's crucial to add hydroponic nutrients or liquid plant food to the water. Regularly monitor and adjust nutrient concentrations based on the manufacturer's instructions to prevent over-fertilization and nutrient deficiencies.
Air Circulation: Roots need oxygen to thrive. Ensure the hydroponic container allows air exchange or introduce oxygen into the water using an air pump or air stone. Proper aeration prevents root rot and supports healthy root growth.
Houseplant Watering Tips
Tap water can contain chemicals such as chlorine, fluoride and high mineral content, which can lead to a buildup of salts in the soil and cause root damage.
To avoid these issues, it is recommended to use distilled water, rainwater, or allow tap water to sit for 24 hours before using it to allow the chemicals to evaporate.
Using water that is too cold or too hot (room temperature is best).
Using a pot without proper drainage which causes water to pool and plants to become overwatered.
Not checking soil moisture levels (each plant has different needs depending on size, type, and growing conditions).
Yellowing Leaves - Be cautious of yellowing leaves, as this can be a sign of overwatering as well as many other things depending on the plant.
Placing an ice cube on the soil can lead to uneven watering and temperature shock which can damage the roots of the plant and lead to stunted growth.
Unlock your houseplants' growth and health potential by experimenting with different watering methods. Our adaptable pots facilitate both top and bottom watering, while also supporting hydroponic media. Happy Gardening! -Rikki
USGS - Capillary Action and Water Capillary Action and Water
Houseplant Resource Center - Bottom Watering Plants | How to Do it the Right Way
Plant Care Today - What Is the Soak and Dry Watering Method?
(University of Maryland) 1