Water Lilies

Water lilies (Nymphaea) are the queens of water plants, with their sumptuous, chalice-like flowers that sit on the water surface, but they also have a practical function as their large leaves keep the water cool in hot weather.

Water lilies must be grown in still, not
running, water in full sun.

How deep does the water need to be to grow water lilies?

A water depth of at least 45cm 
(18in) is needed to grow most 
water lilies successfully. Equally important is the water surface area. Water lilies are vigorous plants and some have a spread that can only be accommodated by larger ponds. Check the ultimate spread of any variety you buy. Miniature water lilies are available that will grow in shallower water in smaller ponds.

What is an aquatic basket?

An aquatic basket is a plant pot 
used for water lilies and other deep water plants. Unlike conventional plant pots, they are usually wider 
than they are deep, and often 
square in shape, with sides sloping outwards towards the top. The sides and base are perforated. They are always made of plastic or another synthetic material that will not rot in water. The mesh is usually fine, to retain the soil.

When is the best time to plant a water lily?

Water lilies die back in winter to an elongated, knobbly tuber. It is best to buy them as bare tubers in early spring when they are just beginning to put out fresh growth. This is the most practical time to handle what will be a large and unwieldy plant (if removed from the water by summer). You can also easily identify which way up to plant the tuber. Plant as soon as you can after purchase. Water lilies will not tolerate drying out, as they are adapted to permanent wet conditions.

Do I need a special potting mix for a water lily?

Although you can buy aquatic potting mix, ordinary garden soil is perfectly usable for growing water lilies. The soil should not be too fertile or have been recently manured – rich soil will turn the water green.

How do I plant a water lily?

Choose an aquatic basket that will easily accommodate the tuber with room to spare, and line it with 
hessian (burlap) or lawn turves (grass side outwards). Fill with garden soil, then the tuber, buds facing upwards. Add more soil around the tuber if necessary, but do not cover the top of the tuber or the buds. Place stones on top of the soil around the tuber.

Why do I need to put stones on top of the planting?

The stones fulfil two important functions. They help weight the basket down so that it sinks to 
the bottom and also prevent the soil from floating away into the water.

Nymphaea ‘Albert Greenberg’ is a
tropical water lily that requires a warm
temperature, otherwise it will not flower.

How do I get the water lily into the pond?

Actually, planting the water lily in 
the pond is a tricky business and 
may require the help of an assistant. Assuming you have room for only 
one water lily, it should be planted 
as near to the middle of the pond as possible. Working solo, this will mean stretching across the pond. It is easier to support the basket on two long canes, one in each hand, the assistant holding the other ends. Suspend the basket over the water in the desired position. Gradually lower the basket into the water, but do not submerge it fully. Wait until the soil in the basket is saturated with water, then gently release is so that it drops to the floor.

Can I grow tropical water lilies?

Tropical water lilies are very beautiful, with a wider colour range than hardy ones. Orange and blue varieties are available, and some are scented. 
As permanent plantings, they need a minimum temperature of 10ºC (50ºF) in winter. You can grow them successfully in frost-prone areas, 
but need to lift the tubers annually 
in autumn for overwintering in 
damp sand at a minimum temperature of 10ºC (50ºF). Return them to the pond in mid- to late spring once 
there is no longer any risk of the water freezing.

How do I divide a water lily?

In early to mid-spring, pull up the basket containing the water lily rhizome from the base of the pool. 
If very large, it may well have outgrown its basket. Wash the rhizome clean of mud under running water. Cut it into pieces, making sure each section has root and leaves (or leaf buds). Return one piece to the original basket, potted up in fresh 
soil topped with stones, then put 
this back in the pond. You can 
grow on smaller sections in pots of ordinary garden soil topped with grit. 
Put these in bowls of water and keep 
them in a shaded place. The plant needs to be kept permanently submerged, so keep adding water as necessary so that the leaves float on the surface. They should be big enough to plant out the following year. If you intend to give some of the cuttings away, simply seal them in plastic bags to retain moisture.

Dividing a water lily

1: Lift the rhizome from the pond in early spring, but before any leaves have reached the top of the pool. Cut this into sections, each one with at least one strong growth bud.

Picture of Patio Planting

2: Replant each section in its own basket, filled with ordinary garden soil or aquatic potting mix. 
Top with stones, then return the water lily to the pond.