H2O, Aqua, water. One of the sources of all life! Also sometimes used on its own to grow plants in. All you need is a clean container, without drainage holes, and some water. The cleaner water the better!

Fill up your container and place your soilless plant in the water and watch it grow.  

If the container is see-through, some algae may start growing, especially if you fertilize your plant. So, don’t forget to clean the container and change the water now and then.