Waterlilies and Other Deep-Water Aquatics

Some waterlilies have thick, flattish, creeping roots; others have pineapple-shaped roots. When planting, the fleshy rhizomes of the creeping root type should be laid horizontally under about 2.5 cm (1in) of soil, while the more upright, pineapple-shaped root is planted vertically or at a slight angle, with the crown or growing point almost exposed at the surface. Whatever the type of root, ensure the crown is planted shallowly.
Before planting, trim off the fibrous roots and examine the root carefully for any signs of damaged or diseased tissue. Cut out any suspicious material and dust the exposed tissue with fungicide.

The leaves are often damaged in transport, and it is far better to remove these leaves before planting than to allow them to rot off. Even if all the foliage is dead or damaged, the plant can still survive at planting time. During planting, keep the foliage cool and damp, and never leave plants exposed to sun or dying wind. When you are planting a waterlily in a container, choose a large size of crate, and firm the soil thoroughly around the root stock because, once all the air is expelled by firming and the soil is saturated, the volume will shrink considerably. If the soil has been inadequately firmed, containers will only be half full a short time after immersing.

It is, therefore, a good idea to water thoroughly before planting and to add any extra soil that may be needed. Finally, when the soil has been firmed, add a layer of pea gravel about 2.5 cm (1in) deep. Plant shallowly, using bricks under the container, which can be gradually removed when growth starts. Containerized planting for deep-water plants largely follows the method described above for waterlilies.

The technique for planting tropical waterlilies is similar to that for hardy plants, although it varies in a few important ways. The tropicals are generally more vigorous and faster growing than the hardy plants, and they should be given large containers. In most temperate climates their cultivation is restricted to pools in conservatories where water temperatures of 24-29˚C (75-85˚F) can be guaranteed. In the temperatures below 21˚C (70˚F) the young tropicals frequently go dormant. In temperate climates they should be planted later than the hardy waterlilies shat the warmer water will encourage rapid development.

The hardy plants are sold as rootstocks of the parent plant, but tropicals are sold as complete young plants. These are planted into containers as described for the hardies, but a sachet of slow-release fertilizer should be added to the planting medium, They are planted shallowly and, unlike the hardies, do not need to be gradually introduced to deeper water.

They flourish in surface water that warms up quickly in the sun. For both hardy and tropical waterlilies, anticipate the problem of reaching the deeper area of the pool with a container full of compost (soil mix) which is often heavy. For larger pools, you will need to wear waders to reach the deeper area.

Planting A Waterlily

Increasingly, waterlilies are being sold in aquatic baskets ready for planting; these will be adequate until the plant needs dividing.

1. Do not plant the young containerized plant too deeply until it is established. Build a temporary brick pier so that the top of the container will be approximately 15cm (6in) below the surface of the water.

2. Remove any old or damaged leaves which will soon rot in the water. Gently place the container on top of the support.

3. As the plant grows and the leaf stems elongate, remove on layer of bricks at a time until the plant is strong enough to be placed on the pool bottom.