Hydroponics: easy to start, hard to master
Hydroponics is undoubtedly an exciting hobby that will never bore me. That's because it isn't so inaccessible or cost prohibitive that I would have given up before even starting, but at the same time there are always ways in which you can improve.
It isn't difficult to get started with indoor hydroponics, but what if you truly want to master hydroponics? This is where things are endlessly challenging, and it can even be difficult to define what it means to succeed. Is it enough to say you were able to grow a couple of leafy greens for your salad? Or to harvest a head of lettuce within 30 days? Or to be profitable and yield enough produce to be cheaper than buying at a supermarket? What about all the different species and sub-species?
Plants have evolved under natural conditions to be relatively hardy and can usually withstand a variety of conditions - for baseline success, just provide them with environmental conditions that are sufficient for them to grow.
For indoor hydroponics, that typically means providing an acceptable nutrient solution and enough artificial lighting. Achieving these two is actually relatively straightforward and getting started is not very challenging, and one of the main reasons for this website is to help more people get started with and appreciate the joys of indoor hydroponics in their own home.
But what if you wanted to do better than just "acceptable" and "enough"? What makes indoor hydroponics so challenging and fun to try to master is that there are so many variables and factors that go into a plant's growth.
I've distilled the various factors that need to go into "mastering" hydroponics into an equation:
Success = (timing) x (lighting x solution x species x environment) - cost
This isn't literal mathematical function but simply a representation that shows the relationship between the factors that you would consider when asking what it takes to master indoor hydroponics.
First, the combination of 4 primary factors over time, namely lighting, solution, species and environment, will determine the amount and quality of what you grow. Note that these variables certainly are not linearly positive or constant - for example, increasing lighting levels may help until a certain point (e.g. 18 hours) but after that, you may see diminishing effects on growth or even harmful effects as you near 24 hours. The timing effect of when is also important. Should you give your seedlings 24 hours of light first, then lower it to 12 hours? How would that compare to if you just did 18 hours throughout its whole life cycle? Also keep in mind that success might not necessarily be total yield or quantity, but aesthetics or taste.
Second, you must subtract cost from your equation. The equation simply illustrates the fact that all else equal, as costs go up, your success will generally go down. To what extent this is important or weighed is a completely personal decision, but should nonetheless be factored in. Don't forget that your time also has value, although you may or may not want to factor that in if it is a hobby.
Below are additional details on how each of the factors might influence your indoor hydroponics success.
The main factors involved with lighting are energy intensity, duration and distribution of energy across wavelengths. You could have a lower intensity light shining for 18 hours, or a higher intensity lighting shining for 12 hours - which will result in better growth? Or make adjustments to your spectral power distribution to emphasize energy in particular wavelengths.
Solution (nutrients & pH)
The N-P-K balance and overall concentration would be the key factors to look at here in terms of nutrients. You might try a higher nitrogen concentration but lower PPM/EC overall, or vice versa. You will want to look at a variety of pH levels as well to see how it affects growth.
Species and genetics
While there is a significant amount of similarity among species, no two species will behave the same and each will have a slightly different reaction to the same conditions. For example, Boston Bibb lettuce may have perform slightly better with higher pH than regular butter lettuce. Even within a species, genetic mutations and selection will affect how they react to environmental changes. Harvesting seeds from lettuce heads that bolt early, for example, could lead to offspring that tend to bolt faster.
Temperature & humidity
Plants have adapted to a relatively wide range of temperatures. Cool season crops like lettuce and spinach are known to tolerate cooler temperatures down towards the 40s, but they also perform well in temperatures close to 70 degrees (very warm temperatures tend to cause them to bolt early). But which temperatures will they perform best in? What about humidity? Another difficult environmental aspect to measure is wind speed and ventilation.
Finally, what is your budget either overall or per unit of yield? Are you trying to make a profit or is this simply a hobby? Either way, all of the inputs above will affect your cost in some way or another - such as increased nutrient use or electricity usage for lighting or heating/cooling.
The point in listing out these factors is two-fold. First, to illustrate the endless possible combination of factors that could either improve or diminish your hydroponics success. Second, is to at least be able to know what we don't know, and to break down the potential factors.
I believe artificial intelligence and big data analysis systems will one day be able to do the heavy lifting, but until then, we will have to continue running our own experiments to try our best to unlock the deepest secrets to indoor hydroponic success!