How to grow waterlilies

What are waterlilies?

These are aquatic plants, of various sizes, for growing in ponds and lakes. They range from large, vigorous cultivars that spread several metres wide, to dwarf forms for small ponds or even a half-barrel. They are one of the most popular and instantly recognisable pond plants.

The opulent, many-petalled flowers come in a choice of colours, including white, pink, red and yellow. They sit on or just above the surface, among the glossy lily pads. 

Waterlilies are perennials, so live for many years, dying down in autumn and re-sprouting in spring. The most widely available waterlilies are hardy, for growing outdoors all year. 

There are also tropical waterlilies, which have large, vibrant flowers. These are tender and need warm water – at least 21˚C (70˚F) in summer.

Choosing the right waterlily

There is a huge range of waterlilies to choose from, with flowers in various colours, adding elegance to both formal and informal ponds. They are beneficial as well as decorative, as they provide shelter for pondlife and the shade they cast helps to deter algae. 

A key factor when choosing a waterlily is the size and depth of your pond. Many waterlilies are vigorous and can spread to cover several square metres, although there are options for all pond sizes. If you don't have a pond, you can still grow a dwarf waterlily in a large container of water (at least 30cm/1ft deep).

Hardy waterlilies are easy to grow outdoors all year round. Tropical waterlilies can be more tricky, as they need warm water and frost-free conditions in winter.

To find out about the various species and cultivars, go to RHS Plant Finder. Search for 'Nymphaea' and you can browse the photographs and descriptions, and find out where to buy them.

For more inspiration and tips, see our guide to pond plants.

How and what to buy

Waterlilies are mainly available from specialist aquatic plant nurseries and online suppliers. 

They may be sold as bare-root plants (without soil) while dormant in early spring, or as growing plants in spring and summer.

They are sometimes available pre-planted into aquatic baskets, ready for placing directly in a pond. Waterlilies need to be planted in aquatic compost or heavy loam, so buying ready-planted specimens is an easy and time-saving option, requiring no specialist products. 

Where to plant

• Waterlilies prefer calm, still water, away from fountains, pumps, cascades or other turbulence.

• Plant in full sun to promote flowering.

• They are best planted in aquatic compost, or heavy clay-based loam, in an aquatic basket.

• Choose a cultivar to suit the size and depth of your pond – check plant labels/descriptions before buying.

• Aim to cover no more than half the pond's surface with leaves.

Most waterlilies are hardy, but tender tropical waterlilies are also available. These need a water temperature of at least 21˚C (70˚F) during the growing season, and 10˚C (50˚F) in winter, so are best grown in pool in a warm greenhouse or conservatory.

Plant sizes and water depths

Dwarf/small cultivars  reach 30–60cm (1–2ft) wide, and need water 30–45cm (12–18in) deep.
Medium cultivars  reach 60–120cm (2–4ft) wide, and need water 45–75cm (18–30in) deep.
Large cultivars  reach up to 2.4m (8ft) wide, and need water 75–120cm (30in–4ft) deep.

When to plant

From late spring to late summer.

How to plant

Waterlilies should be planted into an aquatic basket, with mesh sides, filled with aquatic compost or heavy clay-based loam.

The basket prevents the roots spreading unchecked and makes plant care easier, as it can be lifted out relatively easily. Most waterlilies need a large basket, usually 5–10 litres, although a dwarf plant should be fine in a 2 litre basket.

To plant a waterlily:

• Line the basket with hessian and fill with aquatic compost or loamy soil. 

• Trim back any long roots and cut off old or damaged leaves.

• Plant so the crown is at the compost surface, and firm in well. Add a layer of washed pea shingle to hold the compost in place. Water thoroughly.

• Place the basket carefully into the pond so the crown is covered with 15–25cm (6–10in) of water, and the young leaves float on the surface. You may need to stand it on bricks initially.

• As the plant grows, lower the basket in stages until it sits on the bottom of the pond.

Tropical waterlilies can be planted at their permanent depth immediately as they grow quickly.

For more details, see our guide to planting aquatics.

Feeding

Waterlilies are vigorous, hungry plants. To promote strong growth and flowering, add slow-release aquatic feed every spring. This comes in tablet form, to be pushed down into the compost, so it feeds the plant, not the water.

You can also add these aquatic feed tablets at planting time and when dividing or re-potting plants.

Deadheading

When flowers start to fade, it's best to remove them, if practical, so they don't sink down into the water and rot. If you can reach them safely, cut off spent flowers as low down on the stem as possible.

See our guide to pond care.

Overwintering

Hardy waterlilies need no protection in winter. The leaves will die in late autumn, and should be cut off as low down as possible and fished out, to prevent them decaying in the water.

The plant will stay dormant over winter, then start into growth once the water temperature rises. Leaves usually appear on the surface by mid-spring, depending on your local conditions.

Tropical waterlilies need a water temperature of at least 10˚C (50˚F) over winter. Alternatively, take them out of the pond, remove the fading foliage, then store the tubers in damp sand at a minimum of 10˚C (50˚F).

Caring for older plants

Most waterlilies should be divided every four to five years, to prevent them becoming overgrown and congested, which can reduce flowering. If leaves are pushed up out of the water, rather than floating on the surface, the plant is in need of dividing. 

See our guide to propagating pond plants.

• Remove old yellowing leaves and fading flowers regularly, so they don't sink down into the water and decay.

• In late autumn, cut off all the fading foliage as the plant goes into its winter dormancy.

• It is important to remove fading leaves and flowers, as decaying plant material raises nutrient levels in the water, which encourages algae. It may also deplete the oxygen, which can be harmful to pondlife.

See our guide to pond care.

With hardy waterlilies, the easiest way to make new plants is by dividing established clumps. Tropical species may be grown from bud cuttings, plantlets or seeds. 

By division

Most hardy waterlilies can be divided every four to five years. This not only gives you new plants, but also improves performance, as these vigorous plants soon get overgrown and congested, which reduces flowering.

• Remove the plant from the pond in late spring or early summer.

• Cut the clump into several smaller sections using a sharp knife. Make sure each has at least one young shoot and plenty of fibrous roots.

• Plant the small sections into aquatic baskets filled with aquatic compost. Position the growing point at the surface and spread out the fibrous roots.

• Cover the surface with washed pea shingle, to hold the compost in place. 

• Place the baskets in shallow water initially, until the new plants are producing fresh leaves. Then gradually increase the depth as they grow.

By bud cuttings and plantlets

Tropical waterlilies that grow from tubers can be propagated by bud cuttings:

• Cut sideshoots or new young tubers from the main tuber in spring.

• Plant into a prepared aquatic basket, cover the surface with washed gravel, and immerse in warm water, at 15–18°C (59–64°F).

• As the new plants grow, pot them on, increasing the water depth gradually. 

Some tropical waterlilies produce young plantlets from a node in the centre of the leaves:

• ​Cut off the plantlets in spring or early summer.

• Plant into shallow pans of aquatic compost and immerse in warm water at 15–18°C (59–64°F).

• Gradually increase the depth of water as they grow.

By seeds

• Tropical waterlilies often produce large quantities of seed – these are best sown in spring.

• Hardy species rarely set seed, but if they do, sow as soon as they are ripe, before they dry out. 

The method is similar for both:

• Sow seeds in a pan of seed compost and submerge in 2.5–5cm (1–2in) of water.

• Hardy waterlily seeds need at least 13°C (55°F) to germinate, tropical seeds 23–27°C (73–81°F).

• Transplant them into larger containers as they grow, and gradually increase the depth of water.

Waterlilies don't generally suffer major problems when grown in suitable conditions. However, these can be vigorous plants, so it's important to choose a cultivar to suit the size and depth of your pond – check plant labels/descriptions before buying. 

• Leaves rising above the surface – this may be a sign that the water is too shallow, or the plant is congested and needs dividing or repotting into a larger basket. See our guide to propagating pond plants and planting pond plants.
• Poor flowering or prematurely yellowing leaves – may indicate a lack of nutrients. Insert a slow-release aquatic fertiliser tablet into the compost. Also check that the plant is getting enough sun – most need at least six hours per day.

The main disease to look out for is:

• Waterlily leaf spot – reddish or grey-brown concentrically marked spots on the leaves. Promptly remove and destroy affected leaves to limit spread. 

Several pests can attack waterlilies, however they usually only do superficial, short-term damage and don't generally require treatment:

• Waterlily beetles – adults and larvae eat elongated holes in leaves.
• Waterlily aphids – these can infest the foliage and buds, soiling them with cast skins and sooty mould.
• Leaf-mining midges – larvae can cause extensive damage to leaves in new or refilled ponds.
• Brown china-mark moths – caterpillars make regular rounded holes in leaf margins.

For more details, see our guide to waterlily pests.

Avoid using pesticides on aquatic plants, because of the danger to pond wildlife. Instead you can:

• Hose down the foliage with a jet of water.

• Remove the pests by hand, if you can safely reach them.

• Cut off heavily infested leaves.

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