Staggered Growth

A square foot garden can produce a surprising amount in a small space and those growing the ingredients for the secret family spaghetti sauce will naturally plant the box so they can harvest everything at once.   This a great practice when canning or preserving, but it does not translate so well to aquaponics.   After all, aquaponic plants aren't just a delight on the senses (I'm eyeing you dill), but also contribute to solid filtration and, of course, nitrate absorption;   in other words, they serve a critical role in the balance of the ecosystem.

Seeking to maximize the growing season, gardener's will already have seedlings ready to transplant in empty garden cells.   While you may view this as a bit zealous, this practive of staggered growth, alternating the timing of your transplants, is almost a necessity to maintaining balance in your aquaponics system.   As your fish age, ammonia production steadily increases, requiring an equally increasing ability to remove nitrate.   Look at the example below, where there is a small grow bed with three large plants and one small spinach, all of which are assumed to be fully mature.   Please note that these scenarios and their corresponding data are entirely fictitious and were chosen for conceptual purposes.

The nitrate data shows that over the course of 10 days, the four plants are keeping the nitrates relatively in check.

Shift the slider above to the right to simulate the removal of a spinach plant.   You will see that in the days after the removal of the spinach, you get get a small, yet perceptible, bump in the nitrate levels.   This is as you would expect from a small plant, despite the spinach being a nitrogen hog.   What is important to note is that the remaining plants are still holding the nitrate levels reasonably steady.

If you replay the scenario, but instead harvest the tomato, squash and cucumber, you are left with a lowly spinach to handle the volume of nitrate produced.   Again, slide the toggle below the red chart to the right.

As expected, the change in the nitrate readings is more dramatic.   Not only is the spinach unable to make up for the loss of its companions, but the difference begins to compound on itself.   The excess nitrates from yesterday are added to the new batch produced today and so on.

Staggered planting and maintaining a good ratio of small to large plants is key to avoiding this situation and is easily done by tracking plant ages.   The grow bed below is much like the situation above, where the tomato, squash and cucumber are all nearing their harvest date together, eventually leaving a small spinach to pick up the nitrate absorption slack.   In this case, I paid attention to staggering when I planted my grow bed, but I did not account for the growing cycle of each plant, hence all of my large plants are done around the same time.

Managing staggered growth is critical to maintaining a system balance and is easy to do when you account for harvest periods and plant sizes.

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