Growing Victoria Outdoors
in The Netherlands

by André S.J. van Proosdij, Scientific Keeper Hortus Botanicus Amsterdam
Click images to enlarge

History of Victoria and the Amsterdam Hortus

In 1849 Victoria amazonica flowered for the first time in Europe. This happened at the English estate of Chatsworth. The size, beauty and fascinating story of Victoria made many people want to grow a Victoria themselves. Several tried to obtain seeds or plants. Within two decades dozens of people succeeded in growing a Victoria from seeds to full bloom. In 1859 the Hortus Botanicus in Amsterdam was the first garden in the Netherlands that produced a flowering Victoria. Since then, Victoria amazonica has been a special plant in the Hortus. The flowering of this giant waterlily has always attracted many visitors.

Similar to other botanic gardens, the Amsterdam Hortus too had a special Victoria greenhouse in which a Victoria was cultivated every year. In 1968 the old greenhouse had to be closed as it literally fell apart and there was no money to renovate it. In 1987 and 1993 Victoria amazonica returned to the Amsterdam Hortus. In 1987 it flowered in a temporary plastic tunnel greenhouse. In 1993 it flowered in the new three-climate greenhouse. Unfortunately, the pond in that greenhouse is too shaded, so flowering only occurred in the first year when all the trees surrounding it were still very small.

Victoria Returns

In 2002 the Hortus tried to grow Victoria in a heated outdoor pond. The first year Victoria amazonica was grown. The plants were raised from seeds in an aquarium tank in a greenhouse. By mid-May, the biggest was planted out. To keep the air above the pond warm, the pond was covered at night with a plastic tent. Unfortunately, water condensing on the plastic and dripping down on the Victoria pads caused burned spots. Hence we removed the tent and crossed our fingers that the weather would be nice. Hard winds can damage the large pads and hail is a problem too.

Fortunately, the plant grew quite well without any protection. It produced several flowers and fruits. In 2003 the experiment was repeated successfully, this time using Victoria cruziana. V. cruziana can tolerate lower temperatures than V. amazonica and therefore is better suited for colder conditions. For the past five years we have grown Victorias: in 2002 and 2004 V. amazonica, in 2003, 2005, and 2006 V. cruziana. In 2005 the V. cruziana plant produced 30 flowers between May 29 and October 16.

Cultivation Conditions

The picture at the right shows the outdoor pond. It measures 6 m in diameter and is approximately 1 m deep. On the bottom of the pond is a 20-30 cm layer of sand and mud. In the pond grows a lot of Elodea, Ceratophyllym and a Nelumbo, providing well-stabilized aquatic conditions. The pond is warmed by means of circular heating, connected to the heating system of the adjacent greenhouse.

In the centre a one cubic meter container is situated. The container is filled with a mixture of compost, sand and elephant manure (Artis Zoo is nearby!). Throughout the growing season, additional fertilization (Osmocote) is added. Water temperature ranges from 28 to 30ºC (82-86ºF) and the pH fluctuates between 6.5 and 7.5.

By mid-May, as the Victoria is planted out, the average maximum day temperature is 17 to 20ºC (63-68ºF) and the average minimum night temperature is 8 to 11ºC (46-52ºF). The first flowers appear in late June or early July. New leaves and flowers are produced until October. By then, temperatures become too low for the flowers to open and autumn winds damage the leaves.


The round pond in the Hortus' summer location of Victoria cruziana.
Image by André van Proosdij / de Hortus.


The pond in winter.
Image by and © Yolente Verbeek / de Hortus

The mild and wet Dutch climate is strongly influenced by the Atlantic Ocean and the North Sea. Temperatures are classified in hardiness zones 7 to 8. Amsterdam, situated in the western part of the Netherlands, 52º 22' N, 04º 54' E, fits in zone 8. In addition, the microclimate in the city centre makes temperatures in the Hortus slightly higher.

Outdoor Characteristics of Victoria amazonica and V. cruziana


Victoria cruziana
Image by André van Proosdij / de Hortus.
Outdoor cultivated Victorias show some differences compared to plants cultivated in a greenhouse. The leaves and flowers of both Victoria species are a bit smaller compared to plants grown in a greenhouse. The rims of the leaves are smaller, too. V. amazonica leaves sometimes completely lack a rim. V. cruziana, the leaves of which normally have a much higher rim, produces a rim of 3-8 cm outdoors. Generally speaking, V. cruziana grows slightly better and looks stronger than V. amazonica. This is not surprising, as in nature V. cruziana grows in areas less tropical than V. amazonica. In the Hortus we prefer to grow V. cruziana, as our plant is used for public display and simply has to look good.

Conclusions

The Hortus Botanicus in Amsterdam is the only garden in the Netherlands that grows Victoria outdoors. It is very possible to grow Victoria in an outdoor pond in the Netherlands as long as one creates a situation that answers the plants' demands: high water temperature, lots of sunlight and a rich soil. Covering the pond at night is not necessary, although heavy wind and hail can severely damage the leaves. Plants are smaller compared to plants grown indoors.

Future

In 2006 we tried to raise plants from seeds one generation removed from the wild in Paraguay and Argentina. The parents were collected from populations growing in relatively cold areas. Hopefully, plants from these populations are better adapted to the colder climate in which we grow them. Unfortunately, not a single seed germinated. In 2007 we will try again. It will be interesting to compare the Hortus Victoria results with other outdoor Victoria outcomes in Europe and North America.

More Information

Website of the Hortus Botanicus Amsterdam 
 

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