Microclimates for Rooftops

For the EnergieKas, the Roof Plantery, a 120 m2 greenhouse on a 2000 m2 roof in the middle of the Old Center of The Hague, the Laboratory for Microclimates has built six mini greenhouses to grow tropical edible and usable crops throughout the year that usually come from far away. In this way, residents of The Hague and the surrounding area can get acquainted with edible cacti or succulents and get started with mini microclimate greenhouses for home windowsills. The Energy Greenhouse is a project by architects Iris Schutten and Erik de Jong and for innovative heating solutions we work together with the WarmteLab of Joeri Oudshoorn.

Small Rainforest, (Sub)tropical microclimate greenhouse

In a (sub)tropical climate, the average temperature is above 22°C and in winter between -3 and 18°C. We keep it as warm as possible in this greenhouse with salt batteries (WarmteLab) and compost barrels filled with wood chips that compost slowly so that the soil stays nice and warm, especially in winter time. We also use heat mats if the temperature drops too much during the winter months. The soil in this microclimate greenhouse is woody, compost and humus-rich and moist, like in a tropical rainforest.

What do we see here?

We see heat and moisture-loving plants that like to form a small (sub)tropical rainforest together. For example, the coffee plants in this greenhouse are protected from bright sunlight by Lemongrass or the Banana plant (outside the greenhouse). This also happens in the rainforest.

Dwarf coffee (Coffea Arabica 'nana’) remains small and produces the first coffee berries after 3 or 4 years. Sowing instructions: Soak the seeds in warm water for 24 hours and plant them 1.5 centimetres deep with the flat side facing down. The bean will start to germinate after 3 months.

Tea plant (Camellia sinensis) Young light green leaves are preferably used for the production of tea. These have short white hairs on the underside. Older leaves are darker green in colour and produce a different tea flavour due to a different chemical composition.

Kaffir lime (Citrus hystrix Daon), Djeroek Poeroet. The best citrus tree to sow yourself is the kaffir lime tree. Simply dry the seeds and put them in the ground. You can use the leaves of the Kaffir lime tree as a flavouring, in the same way as a bay leaf.

Lemongrass or Sereh (Cymbopogon citratus) is a plant from the grass family. The species is used in Asian cuisine, especially Thai, Indian, Vietnamese and Indonesian cuisine. How do I grow Lemongrass? Cut a very thin slice from the bottom of the lemongrass and place in warm water, after about three weeks the roots will appear then repot.

Clitoria ternatea: a tropical climbing plant with beautiful, deep blue flowers. We use this natural dye to make ink. In Thailand, a tea is made from the flowers with the same blue effect.

Sesame (Sesamum indicum) Sesame has been grown for thousands of years for its tasty and oily seeds. A small, annual plant Here in the greenhouse or in a good summer in your own garden.

How do I create a (sub)tropical climate at home?

You can make a mini greenhouse from a PET bottle yourself. Cut the plastic bottle halfway, fill with soil, sow, water and put the top of the bottle back on the bottom and secure with tape all around. Place this greenhouse on the windowsill and watering is not necessary.

Mini Sahara, desert microclimate greenhouse

In a place where drought and heat determine the climate, succulents or cacti will mainly occur. A succulent is a plant that stores water, this can happen in the root, stem or leaf. In this desert microclimate, only edible or usable desert plants are growing.

What do we see here?

Here we see plants that can withstand drought well and like some extra sun, the soil in which the plants are grown mainly consists of sand because this drains water well and retains heat;

Aloe Vera (Aloe Vera)
The plant juice is processed in cosmetics such as creams and lotions. The gel has a refreshing taste and can be used in various recipes such as smoothies and sauces. When you harvest the Aloe Vera, it is important to rinse the latex from the gel because it gives a bitter taste. First let cuttings of the Aloe root in water before you put them in the ground.

Agave, both leaves, flowers and seeds are edible. The young flower stems were roasted and considered a delicacy. The fibres are used to make brooms. Well-known is the agave syrup and not to forget the alcoholic drink Tequila.

Disc cactus (Opuntia Ficus Indica) both the leaves (fried or grilled) and the figs can be eaten.

Saguaro cactus (Carnegiea gigantea) is the largest cactus in the world with a height of sometimes more than 12 meters! Occurs in the Sonoran desert in Mexico and the U.S. can become 250 years old. The prickly pears can be used for making jam, jelly, cake and bread.

How do I create a desert climate at home?
Cut a plastic bottle in half, fill with soil, sow, water and put the top of the bottle back on the bottom and secure with tape all around. Place this greenhouse on the windowsill (a south-facing windowsill is ideal) and watering is not necessary.

Only water your cactus or succulent when the soil has completely dried out. Also, cacti and succulents generally need more water in the summer than in the winter.

Note: if you see plants in the microclimate greenhouse that are not described here or if you have other tips or questions, please contact:Note: if you see plants in the microclimate greenhouse that are not described here or do you have other tips or questions?

Contact:

Laboratory for Microclimates, Annechien Meier, Joost Suasso