Chrysanthemums, often called mums, are popular garden plants prized for their vibrant, late-season blooms. Achieving a spectacular display depends heavily on managing their moisture levels throughout the growing season. Because chrysanthemums have a relatively shallow root system, they are sensitive to both drought and overly saturated soil conditions. Proper hydration is the most important factor for ensuring their survival and maximizing flower production.
The Essential Baseline Watering Requirement
For a mature chrysanthemum planted directly in the ground during its active growing phase, a good starting point is to aim for a total of one inch of water per week. This quantity includes any rainfall the plant receives, meaning supplemental watering is only necessary to meet this weekly quota. This amount is generally sufficient to penetrate the soil deeply enough to reach the plant’s root zone without causing saturation.
The goal is to keep the soil consistently moist but never waterlogged, which prevents the shallow roots from drying out. Inconsistent moisture—alternating between parched soil and sudden drenching—can stress the plant, negatively impacting growth and future bloom quality.
Environmental and Situational Factors That Alter Needs
The standard one-inch rule must be adjusted based on the plant’s environment. The composition of the garden soil significantly influences water retention; for instance, sandy soils allow water to drain away rapidly, requiring more frequent, though potentially smaller, applications of water. Conversely, heavy clay soils hold moisture for longer periods, necessitating a less frequent schedule to prevent the development of root rot.
Sun exposure and ambient temperature increase water loss through evaporation and transpiration. Plants in full, intense sun or those subjected to prolonged periods of warm weather will need a greater volume of water to compensate for the accelerated moisture depletion. These conditions can sometimes demand watering twice a week instead of the standard once-weekly schedule.
Mums grown in containers dry out much faster than those in the ground. The limited soil volume and excellent drainage of a pot mean containerized chrysanthemums may require watering every other day, or even daily when temperatures are especially high. This rapid drying rate requires constant monitoring to prevent the plant from becoming irreparably stressed.
Best Practices for Watering Technique and Timing
Determining when to water should involve physically checking the soil moisture rather than relying on a fixed calendar schedule. The simplest method is the “finger test,” where you push a finger about one to two inches into the soil near the base of the plant. If the soil at that depth feels dry to the touch, it is time to apply water; if it still feels damp, postpone watering for another day.
The best time of day to water chrysanthemums is in the early morning, which allows any excess moisture on the foliage to evaporate throughout the day. Watering in the evening or at night can leave the leaves wet for extended periods, creating an environment highly conducive to fungal diseases like powdery mildew.
When watering, focus the stream or spray directly at the base of the plant, saturating the soil deeply to reach the root zone. Deep, thorough watering encourages the roots to grow downward, making the plant more resilient to dry spells. Shallow sprinkling, which only wets the top layer of soil, is ineffective and can promote weak, surface-level roots.
Adjusting Water Needs Through the Plant’s Life Cycle
The watering regimen must evolve through the chrysanthemum’s annual growth cycle. Newly planted mums require more attentive watering until their root systems become established in the surrounding soil. During this initial phase, more frequent, lighter applications of water are necessary to keep the fragile, young roots consistently moist.
Water requirements peak during active growth and heavy blooming, as the plant uses moisture to support flower development. Maintaining consistent soil moisture during this stage is important for maximizing the size and longevity of the autumn display.
Once the flowering period is over and the plant enters dormancy, water needs decrease dramatically. For in-ground mums, once the ground freezes, watering can be suspended entirely until the soil warms in the spring. Potted mums that are overwintered in a garage or cool space still need occasional, minimal watering to prevent the roots from completely desiccating, but they should never be kept wet.