Article 5-3 Growing for Maximum Yield
Growing for Maximum Yield
By Robert Graves
In every aspect of their lives, people love to tweak, tinker or tamper. If someone even suspects that whatever they are doing is not operating at peak efficiency, they will try to push that extra 5% out of their endeavors. Don't think this is so? Well, if you are a woman, hand a man a remote control with a fine tuning button on it, and if you are a man, hand a woman a Cosmopolitan with "Rate your Mate" quiz in it.
Hydroponics is a very exact science. Following the basic principles can achieve great results, but you can fine-tune your system for maximum results. Regis Philbin's face may still look a little too purple, or your boyfriend may not "intuitively respect your wishes before even you know what they are," but you can give your already thriving garden a further leg up with a little added attention. Let's dissect your garden and its components, and see where we might be able to nudge the scales a little further in your favor.
First off, let's look at the nutrient supply. Rate of flow is an important variable, which should be controlled mainly by the nature of your substrate. Consider the characteristics of your grow medium, as its water retention ability (or the industry coined term "wetability") should determine how quickly or how often it should be flooded. Excessive moisture, especially without proper ventilation, can cause infection problems in the form of mold, rot and other contaminants. Make sure that you maintain stable root zone conditions. If you are using an ebb and flood table or comparable product, make sure that your timed releases of nutrient do not overflow, causing your substrate to shift. If the aggregate pieces grate upon each other, they can sever your plant's fragile roots. Also, ensure that the air-water ratio is in the medium and a moderate temperature control (19° - 21° Celsius / 68° - 70° Fahrenheit) is in effect 24 hours a day. Also, ensure that the pH level is stable and in the optimum range for the type of crop you are growing.
Different crops prefer different nutrients. Determining the optimum "juice" for your crop can give it a healthy shot in the arm. Also, as your plants mature, just like a human being, they have different wants and needs during their different stages of growth. Always match the food strength to growing conditions and the growth stage of plants, and always supply the correct nutrient formula for the needs of your crop. Depending on the circumstances, the correct food strength for your crop may vary from 2600 PPM to 0 PPM! In the following few paragraphs, we will explore the various plant stages and the needs associated with them.
Stage 1: Initial Transition (Rooted cuttings / Seedlings to green growth)
This is the formative stage of your plants, where you have cloned a cutting from a parent plant, or planted a seed, and begun the growth process. When a plant is at this stage, it is at its most fragile. Your plant is just realizing it's potential, and is vulnerable to excesses in its environment. Rooted cuttings and seedlings are generally fed a mild (1/3 strength : 300-400 PPM) flowering food mix while under fluorescent lamps. Soft light and mild nutrients ensure that your young plants are not burned out. This nutrient formula encourages good, early root growth, while the low nitrogen / low light levels provided by the fluorescent tubes keep top growth compact. Under these conditions, your plants will manufacture a strong, healthy formative root system, and develop a thick, sturdy stalk.
When your young plants have developed their first couple leaves and are ready to be moved to green-growth conditions, switch to a mild (700-900 PPM) green growth fertilizer mix. The increased light spectrum, stronger nutrient and increased air flow will encourage the plant to expand to fill its new environment. Your crops will become established during this stage as they grow accustomed to their new growing conditions.
As they mature, slowly increase the food strength up to a full strength green-growth mixture (1400 PPM). A larger plant requires more nutrient to fuel it. At this point, your plants have graduated from transition to full green growth stage. This period of development generally requires seven to 10 days for plants to fully realize their potential and acclimate themselves to their new growing conditions.
A plant's formative stage is like a child's formative years. They use this time to strengthen themselves, learn their environment and become adept at functioning within it. Managing this stage well can ensure a healthy, happy mature plant.
Stage 2: Green Growth
Your crop has flourished through a healthy initial transition stage, and has become established. The environment should now be available to the plant at 100% efficiency, in the form of full light levels, full strength air flow through the crops and full strength nutrient solution (1400-1800 PPM). Stable growing conditions such as temperatures, pH and crop spacing have been addressed and new root and shoot growth is progressing. Also, the healthy, balanced environment you have provided your crops should ensure that your plants are pest and disease free.
It is now time to evaluate your nutrient strength levels, as increasing food strength may result in fuller, faster growth. This has two benefits to you, the grower:
- Faster Green Growth Stage (Crops reach "target" size sooner)
- Potential for greater crop yield later
But, before increasing the food strength available to your crop, ensure your garden will benefit from these higher levels. An overly-rich nutrient level can damage your crop. There are some tricks that you can tweak in other areas of your garden to help support the introduction of a higher food strength. Provide higher light levels (1000 watts per 32 sq ft / 3 square meters). Ensure proper ventilation and increased airflow through the plant mass. Regulate your temperature. Above ground zero, keep it moderate, 30°C / 85°F during the light cycle and 21°C / 70°F during the dark cycle. A regulated temperature in the root zone is also key. Try to keep it between 21°C / 70°F 24 hours a day.
Keep monitoring the growing conditions, keeping an eye on pest or disease. Ensuring the optimum conditions discussed earlier help eliminate these intrusions into your garden, but accidents can happen. Also, introducing regular applications of a growth mix or booster treatments could prove beneficial at this stage and CO2 enrichment may also be an option to explore. If you have not altered any of these environmental boosters to your plants, do NOT increase the food strength. Your plant requires all of these factors to be operating at peak efficiency or it cannot process a greater food strength. And if you introduce greater food strengths to a crop that cannot process it, the end result will be the magnification of any problems in your garden.
Modifying your food strength should always be introduced only once your crops have become fully established in their green growth stage. You should introduce gradual increases in the strength of your nutrient, so that you do not stress your plant; an additional 200ppm increase every two or three days should suffice. During this strengthening phase, watch your crops closely. If your plants show any signs of stress whatsoever, reduce the food strength immediately. It is always better to catch any problem early, as recovery is more easily accomplished.
The maximum food strength of your nutrients depends on the type of crop you are harvesting and the environment you have supplied. If you have maximized your environment by introducing and increasing all of the factors discussed earlier, fast growing crops can easily adjust to gradually introduced nutrient-rich mixtures. If your chosen medium is a Sunshine mix or potting soil, you can achieve an ultimate nutrient strength of up to 2100 PPM. Should you be using rockwool, hydro-corn or comparable product you can achieve a nutrient strength of 2300 PPM.
Stage 3: Secondary Transition (Green Growth to Flowering Stage)
This is where some of the growth output of your plant shifts from vertical lift, stalk stability and root structure to the production of flowers. There are some adjustments you may make to your lighting and your nutrient during this stage to maximize your yield. It is especially important to change the nutrient mixture of your food if you are harvesting a short-day crop plant, where the day length has been reduced from 18 to 12 hours. These plants tend to "stretch" during this transition stage and this elongated, spindly growth can complicate plant spacing and create crowding and heat problems later. Another nasty by-product of a plant with spindly stalks and tiny leaves is a susceptibility to pests and disease. To avoid these unnecessary problems, adjust your nutrient solution by lowering the total strength. When the light cycle of your plants drops, drop your food strength by about 200-400 PPM to balance it out. Also, you should lower your nitrogen levels until flowers start to appear. These two modifications will help keep your plants sturdy and compact through the transition stage.
Stage 4: Flowering and Crop Production Stage
This is the beginning of the crop production for your garden. Once you start to notice flowers appearing, all of your hard work is beginning to bear fruit (Please excuse the pun). The appearance of these flowers signals the end of the secondary transition stage and the beginning of the production stage. Be proud parents, your little ones have graduated and are ready to get a job.
At this point, gradually increase food strength again to the levels prevalent in the green-growth stage. You can use the guidelines there to keep a healthy level. Again, just like in that prior stage, monitor your crops closely for stress during the adjustment. And, as always, maintain the healthy, productive growing conditions your plants have been thriving under to this point. One small change you may want to institute is lowering your temperatures slightly. During the light cycle, keep the temperature at 24°C / 80°F and during the dark cycle, drop it to about 18° - 20° C / 60° - 68° F above ground zero. Adjust the root zone temperature to reflect 21°C / 70°F 24 hours a day.
If you went the extra mile during the green-growth stage and introduced all of the environmental boosters to strengthen the nutrient mixture, feel free to do the same here. If during the green-growth stage, your plants thrived with the strong nutrient mixture, now is another time you can apply that boost. Simply match the PPM strength of the flowering mixture to the PPM strength of the green-growth mixture that exhibited the optimum results. As you begin to notice growth slowing up near the end of the flowering stage, lower the strength of the nutrient mix to compensate.
Your plants have now realized their entire growth cycle. All that is left now is to harvest the fruits, or vegetables, of your labour. Maintain a healthy environment through these last periods of your crop's growth, and monitor their stems, leaves and roots for any negative signs. Vigilance, perseverance and hard work can build an amazing garden, but don't forget that like so many other areas of your life, indoor gardening is a learn-while-you-go experience. If one "experiment" fails, you have learned what not to do. Simply start over and apply this new knowledge to make sure the mistake doesn't reappear. Hardly anyone will have a resounding success with their first crop, but by the time they are harvesting their tenth it is all old hat. Roll up your sleeves, dig in and learn.