Hardy Water Lilies

• Hardy water lilies will behave as hardy perennial plants, given the right conditions. The plants are capable of withstanding winter weather and frost, once established, and planted at least 1 foot below the water surface. Flowers grow horizontally, and thus require at least 30 inches or more so the plant can spread across the water surface, unobstructed by other plants or pond features.
  
  

Tropical Water Lilies

• The behavior of tropical water lilies differs from hardy water lilies in terms of the plants' temperature tolerance and blooming characteristics. Tropical water lilies are not able to survive frost and cold weather and plants thrive best when the water temperature is at least 70 degrees Fahrenheit. Otherwise, the plants might stay dormant and have a stunted blooming period. Flowers on tropical water lilies bloom on stems that extend above the water surface.
  
  

Blooming Season

• The start and duration of blooms for both hardy and tropical water lilies will depend on the water temperature, air temperature, depth of planting and amount of sunlight the plants receive. All water lilies need at least five hours of sunlight each day for optimal blooming. When all conditions are right, a water lily can produce 40 or more blooms during its first season. Tropical water lilies typically bloom from late spring through early fall or once the water temperature is over 70 degrees Fahrenheit. Hardy water lilies bloom from summer through fall.
  
  

Potting Medium and Location Cautions

• Water lilies behave best when planted in either plastic, mesh or aquatic fabric pots so the plants are surrounded by soil, and tubers and root systems are protected. They also prefer soil that is neutral to slightly alkaline, and a pH level between 7.0 and 8.0. Do not use organic matter because it can decompose and poison the water lily plant. Avoid planting near water features that empty or spray into the pond, as this can tear leaves away from the stems of the plants, and the water can drown the flowers and plants.
  
  

Fertilizing

• Water lilies are heavy feeders and will demonstrate the most optimal growth characteristics with regular fertilizing. Signs of under-fertilization include a decline in flower production and lifeless-looking leaves. Feed water lilies on a monthly basis with a slow-release fertilizer made for aquatic plants. Poke a hole at least 1 or 2 inches deep into the potting soil, being sure to avoid placing the tablet near growing tips of tuber roots so the plants don't develop root burn. Set the tablet into the soil to release nutrients to the plants.
  
  

Compatibility

• Water lilies have lateral, horizontal root systems. This growth behavior makes it perfectly fine to plant different varieties. If you live in USDA zone 9 and higher, you can experiment with a mixture of hardy and tropical plants, to observe how they behave together and expand your enjoyment of water lilies in your water pond.