Chrysanthemums (mums) are a popular choice for adding color to patios and porches, especially during the autumn season. When kept in containers, their watering needs become more frequent and specific than those planted in the ground. There is no fixed schedule for keeping potted mums healthy; frequency depends entirely on the condition of the soil and the surrounding environment. Consistent moisture is necessary for vibrant blooms, but the time between waterings is highly variable.
How to Determine Soil Moisture
The first step in proper care for a potted mum is to assess the moisture level of the soil before applying any water. Because mums are typically full and often root-bound when purchased, the surface of the soil can be misleadingly dry or moist. The most reliable method is the “finger test,” which involves inserting an index finger about one to two inches deep into the potting mix near the edge of the container. If the soil at this depth feels dry to the touch, it is time to water; if it feels moist, the plant can wait.
Another practical method to gauge the moisture content is the “lift test,” which relies on the difference in weight between dry and saturated potting mix. Before watering, lift the pot to feel its weight; a light pot requires a thorough soaking. This technique is particularly useful for smaller containers, which can dry out completely in a single hot day. Specialized moisture meters offer a more precise reading, indicating the exact percentage of water content in the soil.
Environmental Factors Influencing Frequency
External conditions directly affect the rate at which a potted mum loses water, making a consistent watering schedule impractical. Direct exposure to intense sunlight and high temperatures accelerate evapotranspiration, where water evaporates from the soil and transpires from the leaves. During a heatwave or on sunny days, this increased water loss can necessitate daily watering, or sometimes even twice a day.
Wind is another factor that increases water loss, even when temperatures are moderate, by rapidly moving humid air away from the plant’s surface. The container material influences how quickly the soil dries out. Porous materials like unglazed terracotta allow water to evaporate through the pot walls, requiring more frequent watering than plastic or glazed ceramic containers. Smaller containers hold a limited volume of soil and will dry out much faster than larger pots.
Proper Watering Application and Technique
Once the soil test indicates that a potted mum is dry, the application of water should be done thoroughly. The aim is to achieve “deep watering,” which means continuing to apply water until it flows freely out of the drainage holes at the bottom of the pot. This ensures that the entire root ball is saturated, which encourages the development of a deeper, stronger root system. Shallow watering, in contrast, only wets the top layer and promotes weak, surface-level roots.
Watering early in the morning is the preferred time, as it prepares the plant with a full reserve of moisture to withstand the heat of the day. This timing also allows any water that may have splashed onto the foliage to dry quickly in the morning sun, reducing the risk of fungal diseases like powdery mildew. Direct the water stream only to the soil at the base of the plant, rather than spraying the leaves and flowers from above.
Finally, always check that the pot is not left sitting in a saucer full of standing water. This prevents the roots from accessing oxygen and leads to root rot.