Garden takes a turn

The garden is not doing well. The pH of the nutrient solution is almost always far too acidic (no matter what steps I take to adjust it), and if one plant isn’t suffering, then another is. I appear to have chosen a poor mix of plants—that is, an environment that makes one thrive (say, causing my peppers to flower) causes another one to fail (and my rosemary immediately turns black and curled). Here are some photos from a recent five-week checkup:

I have my doubts about the mechanical efficiency of the system I am using. It has two tiny air stones at the bottom that both oxygenate and circulate the nutrient solution. However, in practice I can see that very little circulation takes place. In a test, I half-emptied the system and refilled it with a new nutrient solution (whose light-red color made it easy to differentiate from the existing solution in the bed). I poured the entire gallon of solution in one corner—the airstones run down the center of the bed, so one corner is the same as any other—after five minutes the new solution had barely moved at all.

pH monitoring has also revealed some complications that may be impeding plant growth. It has been difficult to keep the acidity of the solution down to a normal level, which I didn’t initially think would be an issue. (Not that I didn’t think there wouldn’t be issues—I just anticipated wild swings in either direction, rather than a persistent acid problem…) I’ve posted the readings in a graph below; will Google Docs be smart enough to update it every time I add a new reading? We’ll have to see. I intend eventually to use my server to publish these graphs without needing Google.

These considerations spur me to two actions: to increase the size of the system (in order to better dampen it from shocks like the introduction of new nutrient solution), and to change its main method of circulation to flood-and-drain. This will involve sourcing two larger grow beds and installing them one over the other, much like this arrangement. Flood-drain will, I hope, circulate solution much more efficiently and get more oxygen to the roots. It is also convenient that flood-drain is also the eventual system we’d like to have running when we try adding an aquaculture element to the system.

I have also added a grow light to the setup, and have (but have not yet set up) a large solar panel and charge controller. More about these next time.