Hydro Houseplants - How to transplant from soil to hydroponics
April 16, 20213 min read
Hydroponics is the art of growing plants in water rather than soil.
Hydroponic cultivation will save you from having to keep on top of different watering schedules for different plant species. The plant takes up as much water as it needs, and you only need to change the water infrequently. Hydroponics also does away with the soil-borne pests and diseases that afflict houseplants.
Hydroponic cultivation also adds great beauty to any space. You can experiment with different types of vessels to show off mesmerizing root patterns.
Technically, hydroponics refers to a horticultural technique where plant roots are suspended in nutrient-enriched water. This ‘true’ form of hydroponics does not require any solid medium. Purpose-built equipment holds plants upright as well as oxygenates and circulates water around their roots.
The simplest hydroponic setup involves placing a plant in a glass container filled with nutrient-infused water plus some solid medium. This is often known as ‘soilless culture’ instead of hydroponics proper, whereonly water is required.
If the shape of your container doesn't keep your plant upright, you may also need to insert solid, inorganic materials to anchor the plant. You can use perlite, vermiculite, expanded clay, geolite, coconut coir, haydite, pumice, and rockwool. Rockwool is a fiber made from molten rock, cut into cubes or blocks. These mediums do not contain nutrients as soil does and simply act as anchorage for the plant.
The Pothos plant in the photo below is held in place by the narrow neck of the container, and does not require any solid medium. Some plants like the pitcher plant actively prefer to have their roots clinging to a substrate.
The simpler, ‘soilless culture’ version of hydroponics played an important role in developing the science of plant nutrition during the nineteenth century. Culturing plants in water allowed scientists to easily add and remove particular minerals so that they could determine the effects of each mineral on plants. The figure below is from an 1894 US Department of Agriculture paper on the effects of a particular nutritive solution upon black mustard plants. It shows mustard plants growing in a nutrient-enriched water solution, held in place by lids.
Many of the following species feature a large number of sub-varieties.
Female Dragon Philodendron
Chinese Money Plant (jade plant)
Miniature sweet flag (Acorus)
Screw pine (pandanus)
Herbs that grow well in water
Dark glass containers are best for hydroponics. It will prevent algae buildup in the water from excess sunlight.
To prepare the water, leave tap-water standing for two days. This will remove chlorine.
Liquid plant food or soluble plant food should be added to the water. Use a quarter to half the amount of product per volume than is suggested by the manufacturer’s instructions. It’s always better to underfeed than overfeed your plants.
Top up the water with a few tablespoons of fertilizer water every couple of months. Make up a bottle of this ahead of time for convenience.
Transferring plants to water
To transfer the whole plant to water, remove your soil-grown plant from its pot and submerge the root ball in water to remove any soil. Be careful not to damage the root system when you do this. Once the roots are soil-free, place the root system in your water-filled glass container.
You can also grow a new plant in water from cuttings taken from one of your existing plants. Snip a stem below a node, remove any leaves from the bottom quarter of the stem, and insert the tip of the stem into the water. Place in a sunny position and you will see roots forming.
Changing your water
Change the water in your container completely every month, adding some of the fertilizer solution each time. This will aerate the water.
Oxygenating your water
By completely changing the container water, you will be providing oxygen for the roots. You should do this at least once per month.
You can also top up oxygen levels between water changes by using a bicycle pump to pass air through your water. You could also oxygenate the water by placing easy-maintenance aquatic plants like eelgrass or hornwort inside your container. Keep an eye on these to ensure that they don’t proliferate.