Monday, February 7, 2011

Plant of the Month – Hardy Water Lilies

Water lilies are the jewels of nearly all water garden designs. These beautiful, low maintenance plants form the colour palette of the pond and now is the time of year they’re looking their best.

There are generally two types of water lilies that will grow in Australia, Tropical and Hardy, but being in the cooler regions here in Canberra your best option is the latter, a frost tolerant plant from the Nymphaea family.

At Bliss we have several varieties to choose from including apricots, pinks, reds, whites and yellows. Some even change colours and are referred to as changeable.

The majority of water lilies produce flowers 10-20cm wide. But there are also pygmy or miniature water lilies varieties with flowers as small as 4cm wide. Hardy water lilies flower during the daytime and generally have their flowers floating on the water surface or only just above it.

How do I keep my water lilies flowering?

Water lilies flower during the warmer months; the time and frequency depend on the variety and also the conditions that the plant is growing in. Some varieties flower more than others, but the key to good flowering is sunlight and food. Water lilies need at least 6 hours of direct sunlight in order to flower. Not filtered or reflected light, but directly in the sun's rays. They are also heavy feeders, and as such need a good source of nutrients to give the plant the vigour to grow and produce flowers. Each flower only blooms for 4-5 days so it is important to use good slow release fertilisers to encourage more flowers.

How deep can I plant my water lilies?

To get the best results you need to plant a water lily at the correct depth. Smaller miniature water lilies need only 5-10cm of water over the crown (the growing tip that produces the leaves), making them ideal for planting in bowls and smaller water features. Hardy water lilies prefer the deeper pond water and will grow happily in 40-60cm of water.

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.

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. In Canberra flowering tends to start late September and carry through to about late March.

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.

As with any garden plant, the larger the plant, the more flowers that can be produced. At Bliss we sell only the flowering sized plants, the majority of them in 20cm pots for easy transportation. 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, poorer performing plants.

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.

If you’ve ever considered a water lily for your pond or have been thinking of adding another then now is the time to get them in and established before the cooler months arrive.