Growing citrus trees in containers offers the pleasure of fresh fruit, even in non-tropical climates. Proper watering is crucial for the health and productivity of a potted citrus tree. Unlike plants in the ground, container plants rely entirely on the grower for moisture, and the frequency of watering is dynamic. There is no fixed schedule because a tree’s water needs change constantly based on its environment and growth stage. Successfully keeping a citrus tree requires learning how to assess the soil’s moisture level rather than adhering to a rigid calendar.
Reading the Soil: How to Determine When to Water
The most reliable method for determining when to water is to physically check the moisture content of the potting mix. This process focuses on assessing the top few inches of soil, where moisture is lost first. A simple “finger test” is the most accessible technique for the home grower.
Insert your index finger two to three inches deep into the soil near the center of the pot. If the mix feels completely dry, crumbly, or dusty at this depth, it is time to water the tree thoroughly. Allowing the soil’s surface layer to dry out slightly before watering helps the roots receive necessary oxygen. However, the lower portion of the root ball should never dry out completely, as this causes significant stress and leaf loss.
As an alternative, a soil moisture meter can provide a more objective reading of the water content at various depths. For citrus, wait until the meter drops into the “dry” or lower “moist” range before rehydrating. A consistently high moisture reading deep in the pot signals poor drainage or overwatering, which can lead to root rot. Learning the weight of the pot when fully saturated versus when dry can also serve as a quick, non-invasive indicator of water need.
Environmental Variables That Change Frequency
The time it takes for the soil to dry out is constantly influenced by external factors. Seasonal changes, particularly temperature, have the largest impact on a tree’s water usage. During the active growing season of spring and summer, high temperatures increase the rate of transpiration (water evaporating from the leaves). This means the tree will require water far more frequently, sometimes even daily in extreme heat.
Dormancy and Temperature
When temperatures drop in fall and winter, especially if the tree is brought indoors, the plant enters a period of reduced growth or dormancy. During this time, the tree’s metabolic processes slow down, and it uses significantly less water. The grower must reduce the watering frequency to prevent the soil from remaining saturated for too long.
Pot Material
The material of the pot itself also influences moisture retention. Porous containers, such as unglazed terracotta, allow water to evaporate through the sides. This causes the soil to dry out much faster than non-porous plastic or glazed ceramic pots.
Air movement and humidity also play a role in the rate of water loss. Low humidity and high airflow, common in arid climates or near a heater vent indoors, increase the rate of evaporation from the soil surface and the leaves. A tree that is root-bound or large for its container will dry out much faster than a small tree because the ratio of root mass to soil volume is much higher. These factors necessitate continuous observation rather than a set schedule.
Effective Watering Practices for Potted Citrus
The method of application is important for promoting deep, healthy root growth. Water must be applied slowly and thoroughly to ensure the entire root ball is saturated. Continue watering until water flows freely from the drainage holes. This practice, known as leaching, is essential because it flushes out accumulated mineral salts that can burn the roots over time.
Avoid giving the tree small, shallow amounts of water. “Little sips” encourage the roots to stay near the surface, making the tree less resilient to heat and rapid drying. After a deep watering, ensure the container is not left sitting in a saucer of standing water for more than an hour. Prolonged contact with standing water can suffocate the roots, preventing oxygen uptake and leading to root rot. Observing the tree and adjusting your technique based on the soil’s moisture level remains the best strategy for a thriving potted citrus tree.