Indoor Tomato Outperforming The Outdoors

A project log for MoAgriS: Modular Agriculture System

Growing food crops and other plants in small indoor spaces using established containers like regular plant pots and very little money.

Prof. FartsparkleProf. Fartsparkle 05/12/2018 at 11:560 Comments

My experiment started a few weeks ago to see how the growth of a tomato from the same pack of seeds would compare by being grown indoors with MoAgriS vs. being grown outdoors in the sun.

The difference is quite staggering. Even though I live in a very mild area where there is even wine growing and the fact that we had the warmest April in the history of temperature recording; The outdoor tomato(s) are very far behind compare to the indoor tomato.

Both plants started out as seedlings in the inside grown with the lamp modules, when it got regularly over 20°c outside and not much under 15°c at night I put all but one tomatoes outside in a spot that would get sunlight all day. While the indoor tomato would get light for about 10h a day (which of course comes with a slightly increased energy bill vs free sunlight outdoors, so if you can grow outside, I always recommend that economically and ecologically wise).

On the left you can see the outdoor tomato, on the right the MoAgriS grown tomato.

The difference is quite staggering. The indoor tomato is about twice as large, same goes for branch length.

Though it remains to be seen how much this will affect amount of fruits and if the indoor plant will develop fruits at all. While the stem thickness seems healthy for the indoor plant a large plant does not necessarily mean that the plant will bear a lot of fruits, it could also mean it tries to reach the light and puts more energy into growing fast and produces a very thin stem..

Though I think this time around this doesn't seem to be the case, usually the plant will bend towards the light when there isn't enough and the light source is not perfectly above the plant, when I offset the light position for a day the plant would not alter its growing angle or the angle of its branches to get more light.

I did some measurements with a lux meter to see how the new LEDs mentioned in an earlier log perform in terms of light output. The results are pretty great. I measured more than 40k Lux on two 3W LEDs 5cm away. Still far away from the brightest sunlight which is about 100k Lux but given that you never get a perfectly sunny day every day and you can easily add a few more modules to the plant to maximise light output.

I think is might still perform better than growing outside given the consistency of the light output and the consistent warmth inside, plants don't grow if the temp. drops below a certain threshold which is around 15°c for many plants growing in the Mediterranean.

I did not use the automatic watering for this particular plant so far as the water consumption at this stage is very minimal and the sun is not drying out the soil so you only need to water it every few weeks, not a very good test case for watering but this will change once the plant hopefully start bearing fruits.