The current coriander and basil grow has been going quite well and the plants are well established, with a lot of healthy roots trailing along the bottom of the NFT channels.

However, the coriander started showing a few signs of tip burn (both inner and outer) in the last week, and so I have been trying to address this. EC and pH levels are firmly in the range of recommended values for coriander, so unless my data is wrong or the sensors are reading incorrectly, I think i can discount those as factors. My initial research suggests that the problem may be caused by calcium deficiency which could in turn be caused by a sub-optimal rate of transpiration from the plant leaves. To try and help solve this I added the fan you can see in the top left of the above photo, which I am having on for a few hours a day so see if this encourages greater rates of transpiration as fresh and drier air is constantly blowing over the plants. It will be helpful to automate this and perhaps have a smaller fan to gently get a current of air moving through the plants without using too much excess energy, though more research is required to get the right setup. I am currently not controlling humidity at all within the growing area, which is another area it may be beneficial to address in future.

The other tack I have taken is to reduce the intensity of the lighting. The LED light I have has a dimmer that allows, but it is a bit of an inexact science at the moment regarding light exposure rates and times, so I may end up getting a PAR (photosynthetically active radiation) sensor to measure how much light is falling on the various parts of the system, and adjusting these levels, plus the total number of hours of lighting per day, to achieve a more “debuggable” lighting set-up. The whole point of the other sensors is to be able to home in on an ideal set of conditions, so having such an important aspect as the lighting currently un-monitored is a bit of a hole in the system.

Hopefully the above changes will lead to a reduction in the tip burn in the coriander. The basil has not experienced any such problems, and growth is still strong. The basil grow may have it’s own slight issues but I will go more into that in a future post.