How do Hardy water lilies differ from Tropical water lilies?
Most hardy water lilies have been grown and bred from varieties that originated in the cooler parts of the Northern Hemisphere. They will survive severe frost provided that the rhizome’s (the crown / root stocks) do not freeze. There are no hardy water lilies native to Australia.
The flowers tend to float on the water surface or only just above and can come in a range of colours including – apricots, pinks, reds, whites and yellows. Some even change colours and are referred to as changeable.
Tropical water lilies grow in warmer climates and produce flowers that stand up, typically 30cm high, out of the pond water. Some of the flower colours range from pinks to reds, whites and yellow, but also purples and blues.
The leaves of hardy water lilies tend to have smooth rounded edges, whereas tropical water lilies produce leaves with toothed or scalloped edges.
The 4 key factors to successfully get hardy water lilies flowering.
Hardy water lilies vary greatly in their flowering performance. Some will only produce a few flowers per month while others can produce many each week. The white and paler pink varieties tend to produce fewer flowers. Most hardy water lilies will produce flowers within the first year of being planted, however there are some varieties that only flower once they have almost over grown the container. They need to form a colony (multiple) of rhizomes before they can flower.
Day length is probably the number one factor affecting the ability of hardy water lilies to flower. In the southern states of Australia, the day length change is far greater than in the tropical northern regions. At Oz Watergardens (based in Victoria) we have noticed that flowering coincides with the equinox (when day and night lengths are the same). Hence flowering tends to start late September and carry through to about late March.
The further north (closer to the equator) where the day lengths tend to remain longer, flowering can start earlier and continue for many more months.
Temperature is the second factor that affects flowering. Typically hardy water lilies start to flower at temperatures above 16-18°C. Many of the darker coloured red-pink varieties are susceptible to petal burn at temperatures above 32°C, others that have been bred from colder climate varieties may even slow or stop flowering, in the heights of summer, as it becomes too hot for them.
Plant size. As with any garden plant, the larger the plant, the more flowers that can be produced. At Oz Watergardens we only plant strong, healthy waterlily rhizomes. We strive to sell only the flowering sized plants, growing the majority of our hardy water lilies in 20cm pots. This is the smallest container that you should grow them in. A smaller container will only allow a smaller root system to grow, resulting in weaker, poor performing plants. Ideally, a larger container would be better, but we still need to transport them economically.
Plant vigour. A plant that is growing vigorously is able to produce more leaves and in turn produce not only more flowers but also larger sized flowers. For best performance hardy water lilies need room to grow and lots of food. We recommend using slow release fertiliser tablets inserted into the soil.
- Hardy water lilies need at least 6 hours of direct sunlight to flower. Some varieties such as Nymphaea ‘Chromatella’ can tolerate light shade.