There haven't been many updates regarding my hydroponic foray into growing tomatoes. The reason: well, I haven't really been checking up on them!
In early December of last year, I went on break along with the rest of my school and left my tomatoes to fend for themselves. They were left on a pure water diet, with no nutrients, and expected to look after themselves. The professor who lent me lab space over the past semester was kind enough to top off the reservoir a couple of times, and when I got back they were in good shape. They had sprung some new branches from their main stems, and even put out some flowers! I decided to leave them there, as they were coming up on the end of their normal lifespan and it wasn't costing me anything to keep them running on water. Ultimately, I decided that since they had past their prime and not fruited I was unlikely to get any actual tomatoes off of them and that it wasn't worth the investment of adding nutrients this late in the game.
Of course, nothing lasts forever. About two weeks ago, the same professor informed me that he would need me to move out of the lab to make room for new experiments. My tests were done, and I felt that I had learnt as much as possible with this particular venture, so I decided to take a gamble on moving the system to my room and having the plants live out the remainder of their lives there. Yesterday, we disassembled the support systems and moved everything to my room.
Unfortunately the weather was not on our side: 1F is not gentle on plants. The majority of the stems and leaves flash froze as we moved them outside, and the trip from the science building to my dormitory was not kind either. When I had them set up in my room and they defrosted, I noticed that much of the leaf structure had gone limp (similar to wilting). The explanation? When water freezes, it forms crystals. These crystals can be extremely minute, and when tissue freezes the water crystals that form can puncture cell walls and cause large amounts of damage. This effect is well known in frostbite cases, and a similar thing happened to the plants. The loss of the integrity of their cell walls and structural rigidity made the plants go limp and become quite pungent.
I determined this morning that the plants were unlikely to recover, and that they would certainly need a heavy investment of nutrient and time from me to do so. Today at 11:45 I disassembled the system, and committed the plants to their fate.
The experiment, however, was a success. I feel as though I've learnt a lot, and that the fact that these plants have survived so well and so long is a testament to the robustness of hydroponic cultivation. Some lessons learned:
Keeping an eye on nutrient is key. pH should be adjusted twice a day, otherwise it can get out of hand. Make sure that you prevent as much evaporation as possible - this will keep pH more stable.
Keeping your plants in a clean area will drastically reduce the amount of contaminants such as fungi, algae and bacteria that accumulate in your system.
Sometimes, less is more. If you're using a lot of nutrients and not getting the growth you want, cut back a little and see if it helps. Add nutrient sparingly.
Having good, fast procedures makes things go significantly smoother. Make sure you consider how you're going to fill the nutrient tank, adjust pH, and add nutrient.
For vining species, make sure you have an adequate support system.
Automation can be a huge help, but make sure you have error reporting and fault tolerance in your systems.
Keeping track of data is essential for fine-tuning your system.
Based on the last two points, I'm working on improving my automation systems and data collection. With the new experiences gained from this experiment, I expect things to be much more robust for my next crop. What should I grow? I'm thinking lettuce this time around!