Tropical water lilies and Victoria in Belgium: is it possible?

A blue water lily held on its stem thirty centimetres above the water, fragrant and open at midday: this is the image that makes every aquatic plant enthusiast dream. These flowers are not those of our hardy water lilies. They are tropical water lilies, and even higher on the dream scale is Victoria, with its giant leaves with raised edges. In Belgium, tropical water lilies can be successfully grown in a sunny tub during the summer, provided they are treated as warm-season plants; Victoria, on the other hand, remains a heated-greenhouse plant. Here is what is realistic and how to go about it.

Hardy and tropical water lilies: two different worlds

All garden water lilies belong to the genus Nymphaea, but the cultivated species and hybrids are divided into groups with very different requirements. Hardy varieties, mainly derived from species from temperate regions, can withstand frost as long as their rhizome remains below the ice. Tropical varieties come from warm regions of Africa, Asia, Australia, or America, and stop growing as soon as the water cools.

Nocturnal tropical water lilies open their flowers in the evening and keep them open until mid-morning the following day. They are spectacular, but even more demanding when it comes to heat. For beginners in Belgium, day-blooming tropical water lilies with blue or purple flowers are the most rewarding. Some hybrids are called viviparous: they produce small plantlets in the center of their leaves, a very useful characteristic for keeping the plant from one year to the next.

The real problem in our climate: water temperature

A Belgian garden pond measuring several cubic meters rarely maintains water temperatures above 20 °C, except during heat waves. Nights remain cool, even in July, and a large volume of water takes time to warm up. For a tropical water lily, this means slow growth, few leaves, and flower buds that abort.

The solution is to reverse the logic: instead of heating a large pond, grow the plant in a small volume that heats up quickly. A dark container holding a few hundred liters, in full sun and against a south-facing wall that releases heat in the evening, reaches temperatures in summer that are significantly higher than those of the main pond. That is exactly what tropical water lilies need.

A thermometer in the container is your best tool: as long as the water does not stay above 20 °C day and night, it is too early to put a tropical water lily outdoors. In practice, this generally means early or mid-June, well after the Ice Saints.

Growing in a container: the method that works

The container

A 300- to 500-liter container, 40 to 50 cm deep, is sufficient for a medium-sized tropical water lily. Rectangular, flat-bottomed models are easy to place on a terrace. A dark color absorbs heat more effectively. Avoid very small containers under 100 liters: they heat up quickly during the day but cool down just as quickly at night, subjecting the plant to sudden fluctuations.

The substrate and fertilization

Tropical water lilies are heavy feeders. Plant them in a wide pot (at least 30 to 40 cm in diameter) filled with a specific clay-based substrate for water lilies, covered with a few centimetres of gravel. Add fertilizer tablets for aquatic plants, pushed into the substrate at the start of the season and then approximately every three to four weeks during growth. Leaves that yellow quickly and smaller flowers almost always indicate a lack of fertilizer. To understand the benefit of this targeted fertilization, read why to use fertilizer for aquatic plants.

Planting depth

The tuber must not be buried: only the crown should be level with the surface, while the crown of buds remains exposed. Place the pot so that the top of the substrate is 15 or 30 cm below the surface. A young plant should be placed shallower, then the pot can be lowered as it grows. The basic steps remain those described in our guide to planting water lilies, with more heat and more fertilizer.

The typical calendar

Should you heat the water?

A small submersible or floating heater can extend the season by a few weeks and make cool nights in June or September safer. But let's be clear: a device of a few hundred watts, in an uninsulated outdoor container, will gain at most a few degrees. It will not turn a pond into tropical water, and the electricity costs quickly add up. Reasonable use is as follows:

• in a container holding a few hundred litres, optionally covered at night with a transparent panel;
• to smooth out the nights rather than to heat continuously;
• with an outlet protected by a 30 mA residual-current device and a thermometer to check the actual effect.

Sunshine, a heat-retaining wall, shelter from the wind, and a dark-coloured tank often do more than heating. Combined, they allow abundant flowering from July to September in good years.

Overwintering a tropical water lily

This is the step that discourages most amateurs, and for good reason: tropical water lilies cannot survive the winter outdoors in Belgium, and keeping them indoors requires some method. You have three options.

Option 1: preserving the tuber

At the end of the season, when growth slows, many day-blooming tropicals form a small, hard tuber at the base of the plant. Recover it, clean it, let it dry briefly, then store it in slightly damp sand or in a jar of water, somewhere cool but frost-free, in a temperate room. In spring, place it back in warm, bright water to restart growth. The success rate varies by variety: regularly check for signs of rot.

Option 2: keeping the plant growing

A young plant, or a seedling from a viviparous hybrid, can spend the winter in a heated, illuminated aquarium. This is the safest method, provided you have enough space and lighting.

Option 3: growing it as an annual

Many gardeners accept having to buy their tropical water lily again every spring, as they do with certain patio annuals. Given the spectacle it provides for three months, it is a defensible choice.

Do not confuse this work with overwintering hardy water lilies, which simply remain at the bottom of the pool. For the latter, the general water lily growing advice applies without any special precautions.

Victoria: a greenhouse dream

Victoria (genus Victoria) is a giant water lily from South America, famous for its circular leaves with raised edges that can far exceed one metre in diameter, and for its large flowers, which open white at dusk and turn pink the following night. Victoria amazonica, Victoria cruziana, and hybrids of the two are the main species grown.

Why is it so difficult? Because Victoria combines every requirement: water that is very warm at all times, significantly warmer than for tropical water lilies, intense light, a pond several meters in diameter, and a long growing season. In botanical gardens, it is generally sown every winter in a heated greenhouse and grown as an annual. Victoria cruziana is considered slightly less cold-sensitive than Victoria amazonica, but remains beyond the reach of an outdoor pond in Belgium.

The simplest way to admire it is therefore to visit a botanical garden. In Belgium, Meise Botanic Garden displays Victoria cruziana in the tropical wetlands greenhouse of its Plant Palace. For a private individual, Victoria is only feasible with a heated greenhouse and a spacious indoor pond - in other words, a project on an entirely different scale from a tub on the terrace.

Common mistakes

• Moving the plant outdoors too early: in May, the water is still too cold; the plant stagnates or rots.
• Planting it in the large pond: the water remains too cool there, and the fish, especially koi, damage the leaves and roots.
• Forgetting the fertilizer: a hungry tropical water lily produces a few small flowers, then runs out of steam.
• Burying the tuber: the crown must remain uncovered.
• Adding water hyacinth “to make it look tropical”: this plant is included on the list of invasive alien species under Regulation (EU) 1143/2014 and must not be introduced.
• Leaving the plant outdoors in October: one or two cold nights are enough to compromise the tuber.

Generic practical cases

Common scenario: a south-facing city terrace

A 400- to 500-liter tub against a light-colored, south-facing wall, a blue tropical water lily in a large pot of water-lily substrate, and fertilizer tablets every few weeks. Set up in mid-June, it flowers from July to September. In autumn, the tuber is retrieved and kept in a jar of water in a temperate room.

Common scenario: a hobbyist with a veranda

The plant is started in April in a heated, illuminated indoor tub, moved outdoors for the summer, then brought back under the veranda in September to extend flowering. A seedling of a viviparous hybrid is kept in an aquarium as insurance for the following year.

A common case: the Victoria dream

A hobbyist wants Victoria in his pond. After discussion, he opts for a tropical water lily in a container for the terrace, and a summer visit to a botanical garden for Victoria. The enjoyment is there, without an excessive heating bill.

Read also

Growing in a container, step by step: How to grow water lilies in a barrel.

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Frequently asked questions

— Can a tropical water lily stay outdoors all year round in Belgium?

No. It stops growing as soon as the water cools and does not survive the winter outdoors. Bring it indoors in autumn, preserve its tuber or grow it as an annual.

— When can you put a tropical water lily outside?

When the water in the container stays above approximately 20 °C day and night, which generally corresponds to June. A thermometer in the water makes it possible to decide without guessing.

— Can you grow Victoria in a garden pond?

Not in our climate. Victoria requires very warm water at all times, strong light and plenty of space: it is grown in a heated greenhouse, as in botanical gardens.

— How can you tell a tropical water lily from a hardy one?

Its flowers are often held well above the water, may be blue or purple, and its leaves frequently have toothed or wavy edges, unlike hardy water lilies.

In summary

• Tropical water lilies require water above approximately 20 °C to grow and flower.
• Growing it in a dark container, in full sun and sheltered from the wind, is the key in Belgium.
• Specialist substrate, a large pot and regular fertiliser: these are hungry plants.
• Overwintering by preserving the tuber, in a heated aquarium or as an annual.
• Victoria remains a heated greenhouse plant, best admired in a botanical garden.

Last updated: October 3, 2026.