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Image by thomas heintz

Planter experiment @ Hortus

Planter project Hortus and Tulip Mania

In addition to the citizen science project, where tulips are planted in various gardens of Leiden's residents, Tulip Mania Leiden is working closely with the Hortus Botanicus and the Leiden Center for Applied Sciences on a more controlled experiment. On November 24, 2021, organic tulip grower and soil coach John Huiberts planted, together with Hortus employee Theo Houthoff, red organic Tulipa Masterpeace tulips in 11 planters, one of which is filled with just sand as a control, and the others with two different kinds of soil, i.e. soil from John's own tulips fields, or the "Leidse mix" soil that is used by the city of Leiden in green spaces. In the spring, when all tulips are growing and blooming, samples of the soil will be collected from each planter and analyzed using metagenomics. 


Theo Houthoff and John Huiberts fill the planters with different types of garden soil.


Organic tulip farmer John Huiberts with the bags of Masterpeace Tulipa bulbs, available at the Hortus.

Festive tulip planting in de Hortus!

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Behind the planters are people who are involved in the Tulip Mania project. On the right, initiator, Dr. Leonie Kaptein 

On December 14th, 2021, during the winter afternoon at the Hortus, the tulip bulbs with a different color were added to the planters with the previously planted red Tulipa Masterpeace tulips. This was done to show what that tulip will look like in the spring, because one in 25 sold tulip bulb bags contains one such a different tulip. Anyone who will see this tulip grow among the red Tulipa Masterpeace tulips can have their soil analyzed using metagenomics. The planting moment was a festive continuation of the earlier planting moments that took place in the fall. In addition to Tulip Mania initiator Leonie Kaptein, Arjen Speksnijder was present on behalf of the Leiden Centre for Applied Biosciences, Carla Teune and Theo Houthoff on behalf of the Hortus.  

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Carla Teune talks about the history of tulips and the role of the Hortus.

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De tulip bulbs with the deviating color are planted between the red Tulipa Masterpeace bulbs. In the spring everyone can see what color the tulip has! If you bought a bag with bulbs and this tulip shows up, you're the lucky winner to get your soil analyzed using metagenomics.

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Students of SV Nucleus selling the Tulip Mania bags at the Hortus.

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The goal of  the Tulip Mania project is to make the hidden life in the soil visible using metagenomics whereby the DNA of all the micro-organisms in the soil is analyzed.

Foto's: Simone Both

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