Avocado or Persea americana is very easy for experimenting with hydroponics.
Take the kernel or pit (this is actually the seed) from the avocado, let it soak in water to germinate the seed and plant it in earth or in passive hydroponics.
This one is placed in a recycled plastic smoothie cup, immersed in water.
Change the water (depending on how much sunlight it is exposed to) at least once per week.
After a few weeks the avocado seed germinates. It splits open, the germ appears at the top (pointed end of the avocado seed), the roots appear at the bottom end (the blunt side of the avocado seed).
This avocado seed may be planted in a passive hydroponic setup: fill the pot with hydroton (expanded clay pellets) and fill with water right up to the pit. The roots are not very long at this stage and you do not want the seed to dry out in the upper part of the clay pellets.The avocado seed may be fully or partially covered by the clay pellets, it does not matter.
I covered the smoothie cup with its lid. There is a hole at the top for the drinking straw, this ensures sufficient ventilation.
After about 1-2 months the stem and first leaves appear. The pot is now too small for the roots and the plant is transplanted into a larger pot.
I used a recycled plastic bottle, cut off the top part (about 1/3) in order to obtain a sufficiently high pot.
Source: Own work | CC BY 4.0
The avocado is removed from the cup and the roots are rinsed with tap water. The clay pellets stuck between the roots may be left there.
The avocado is transplanted into a new and bigger pot, until it has grown yet again so much that the roots are too tight and it needs a bigger pot.
- I did not use an inner grow pot for this plant: it is easily repotted without damaging the roots
- I have used translucent plastic pots used for the photos and because it is easier to control the growth of the root system but you should use a pot that does not let light through to prevent algae growth.
Click here for further information on avocado (Persea americana).