Tropical House

The summer of 2026 will be the year of the cruciferous plants. Brassicaceae (cruciferous plants) are a family of plants within the order Brassicales – best known for their numerous varieties of cabbage, which are among the world’s most important vegetable crops.

This family includes, amongst others, white cabbage, red cabbage, pointed cabbage, savoy cabbage, Brussels sprouts, kale, cauliflower, broccoli and kohlrabi – most of which have evolved from wild cabbage. Cabbage is rich in vitamins, fibre and minerals. Radishes, rocket, mustard and rapeseed also belong to this family. A characteristic feature is the four petals arranged in a cross-shaped pattern, which give the family its name.

The family comprises around 370 genera with some 4,000 species – including numerous cultivated varieties and breeds that differ in growth habit, leaf structure, colour, flavour and use.

Amaranth (Amaranthus) is a genus of plants in the amaranth family (Amaranthaceae) – versatile as both a food crop and an ornamental plant. The edible seeds are rich in protein, fibre and minerals and are used in cooking as a gluten-free alternative to cereals, for example in muesli, soups or baked goods. At the same time, amaranth delights with its bright red, purple or golden flowers. Thanks to its undemanding nature and hardiness, it thrives in many climatic zones and is a sustainable asset to agriculture and horticulture. The genus comprises around 60 to 80 species, as well as numerous varieties and cultivated forms.

The summer of 2024 was the year of the marigold. The marigold (Tagetes) belongs to the Asteraceae family. Also known as the marigold or, in the Lower Rhine region, as ‘Stinkerkes’, it is far more than just a colourful flowering plant.

Its characteristic scent repels insects such as mosquitoes and aphids. The natural pyrethroids it contains ward off aphids, spider mites and whiteflies, amongst others; marigolds also keep nematodes, which can damage plant roots, at bay. Through its roots, it enriches the soil with nitrogen, thereby benefiting neighbouring plants. As snails love it, it is often planted amongst vegetables as a distraction.

Among the 50–60 species, there are many edible varieties such as liquorice marigold (T. lucida) or lemon marigold (T. lemmonii). Oils – used, for example, to treat skin irritations – are extracted from the flowers; they can also be used as edible flowers or in tea. From May onwards, marigolds thrive in sunny to semi-shaded locations and are a favourite with bees and bumblebees.

In 2023, the sunflower was our ‘Crop of the Year’. With its magnificent blooms from July to October, the sunflower (Helianthus annuus) symbolises a sunny summer – and provides an important source of food for insects and birds. Many people use sunflower oil and sunflower seeds in their diet.

The Tropenhaus team has cultivated a wide variety of cultivars of this species, which originates from the Americas and belongs to the Asteraceae family: alongside ornamental varieties, these include varieties for food, oil and animal feed. As part of the compulsory elective module ‘Focus Field Plant’, students studying sustainable agriculture undertook two projects on sunflower cultivation and presented their findings to the public on 20 June 2023.

Bees are a vital part of our ecosystem – after cattle and pigs, they are the third most important livestock species in terms of their pollination services. Rhein-Waal University of Applied Sciences hopes that beekeeping will enhance its laboratory facilities and enrich its teaching, with all faculties able to contribute.

On 22 March 2017, a bee enclosure was set up in the orchard meadow by the greenhouse; at the same time, two bee colonies were moved into single-chamber hives. In the first year, beekeeper Marco Janßen from Bedburg-Hau looked after the colonies and taught the team the basics of beekeeping. Since 2018, master gardener Franz-Josef Kuhnigk and his team have been looking after the bees. The plan is to have two productive colonies and a display hive with a small colony for public engagement.

The university is a member of the Kleve-Kellen Beekeepers’ Association, which organises information events on bees, beekeeping and honey. Would you like to make your own surroundings more bee-friendly? We’d be happy to help.

Biodiversity is the alternative to monoculture – species diversity rather than mass production. Whether it be cocoa, coffee, cultivated bananas, wild bananas, sugar cane or baobab (monkey-bread tree): This state-of-the-art tropical greenhouse houses a wide variety of exotic plants within a small space and serves as a unique teaching and learning resource. Crops from temperate, tropical and subtropical regions provide direct access to the curriculum of the various degree programmes offered by the Faculty of Life Sciences.

Our strategy for combating pests and diseases is integrated pest management – incorporating crop hygiene, variety selection, optimal growing conditions, beneficial organisms and gentle liquid manures. In the demonstration gardens, we grow native plants according to organic principles: vegetables, fruit, cereals, arable crops, herbs and catch crops, as well as flowers and specific bee forage – and we are involved in beekeeping.

This means you can see and touch the plants we discuss first-hand, examine pests and diseases, and learn how to work with plants and conduct experiments through practical projects. The close proximity of the lecture theatres to the greenhouse makes it easy to tend to your own project even during lecture breaks.

Annual themes from previous years

• 2019 – Raised beds and urban gardening
• 2018 – Walnuts
• 2017 – Hops
• 2016 – Strawberries
• 2015 – Pumpkins
• 2014 – Potatoes
• 2013 – Tomato