The question of how often to water lilies has a complex answer because the term “lily” is used for two fundamentally different types of plants: aquatic species that live submerged in water, and terrestrial varieties that live in soil. Their care routines are entirely separate. The frequency of watering depends entirely on whether the plant is a true aquatic species or one of the many terrestrial varieties that simply share the common name.
Clarifying the Term Lilies
The plant most commonly associated with the name is the aquatic water lily, belonging to the genus Nymphaea. This plant is a true hydrophyte, adapted to living in an aquatic environment where its roots are anchored in submerged soil and its leaves float on the water’s surface. True water lilies do not require traditional watering; instead, they need their surrounding water level to be constantly maintained.
In contrast, many garden plants are also called lilies, but they are terrestrial plants requiring soil and regular irrigation. These include Daylilies (Hemerocallis), Canna Lilies, and true Lilies (Lilium), which grow from bulbs or tubers in garden beds. These land-based varieties would quickly rot if submerged like a water lily, so their care involves managing soil moisture.
Maintaining Water Levels for Aquatic Water Lilies
Caring for true water lilies (Nymphaea) involves managing the depth of the water column above the plant’s crown, not watering the plant itself. The ideal water depth varies significantly depending on the cultivar. Dwarf varieties need 15 to 25 centimeters (6 to 10 inches) of water over the crown, while medium-sized water lilies require 45 to 75 centimeters (18 to 30 inches) to thrive.
The water level must be checked frequently, especially during the active growing season due to high rates of evaporation. Ponds or containers exposed to full sun and wind will lose water daily, requiring regular topping off with fresh water. Insufficient water depth can cause the pads to become exposed to the air or cause the water temperature to fluctuate, which stresses the plant.
Water should be added to the pond or container as soon as the level drops noticeably. This could be daily in a small container during a heatwave, or weekly in a larger, established pond. The objective is to keep the water level consistent to ensure the floating pads are supported and the plant’s crown is submerged. If the water level drops too low, the plant’s leaves may rise above the surface or display signs of wilting, indicating immediate refilling is necessary.
Watering Schedules for Potted and Garden Lilies
Terrestrial plants commonly referred to as lilies, such as Daylilies, require a watering schedule that focuses on maintaining consistent soil moisture. These plants are watered by applying moisture directly to the soil surrounding the roots. A guideline is to provide roughly 2.5 centimeters (1 inch) of water per week during the growing season if rainfall is insufficient.
The frequency of watering is best determined by checking the soil condition using the “finger test.” Push a finger 2.5 to 5 centimeters (1 to 2 inches) deep into the soil near the plant; if the soil at that depth feels dry, it is time to water again. Potted lilies will dry out faster than those planted in the ground and may need water every few days, especially in hot conditions.
It is beneficial to water deeply and less frequently rather than applying shallow, daily sprinkles, as this encourages the development of a strong, deep root system. Deep watering ensures that the moisture penetrates 20 to 25 centimeters (8 to 10 inches) down into the root zone. Watering during the early morning is recommended to allow the foliage to dry before nightfall, which helps minimize the risk of fungal disease.