Aeroponics - Misting Frequency and The Root Systems
Aeroponic systems, which use a mist of nutrients over the plant roots, inside a growing chamber. Producing faster growth rates, high yields and healthy roots. As long as the plant rooting chamber is being kept between 62F - 71F consistently. Some of the more sophisticated commercial greenhouse systems are temperature linked. The temperature is continually monitored in the root chambers, when pre-set temperature is triggered the mister system is activated to bring temperatures down.
Simple Misting Time
One method of delivering nutrient spray in commercial aeroponic systems is the 'regular, intermittent misting cycle'. This is a burst of nutrient solution, misting 3 minutes every 5 minutes. By using this technique, which does not change during the life of the crop, the misting cycle never causes the plant's roots to dry out. The emphasis here, is on regularly delivery fresh aerated, temperature adjusted nutrient to the root zone.
Continual Misting with Proper "Conditions"
With proper oxygen and temperature ( 62F - 71F ) in the nutrient solution in the aeroponic growing chamber, the plant root system will not become water logged or root rot problems. The plants root system on continual misting cycle will produces extremely healthy roots and high yields of plant material. Continual misting eliminates the problems of roots drying out between misting cycles and is one way of ensuring temperatures in the root zone stay stable and do not fluctuate.
The Need for Tweaking
Aeroponic timers allows the grower ability to adjust the frequency of the on/off misting or spraying cycle as well as how long the roots are misted for. FHD has discovered that by changing the cycle timer during the plant stages of life, we received overall better production without adding higher cost in the systems. This idea is based on applying more oxygen to the root system than continual misting cycle. When using this type of system the following points should be taken into account.
1. There is not one set ideal misting program, the amount of nutrient mist time required, is largely depended on the plant, stage of development and more importantly the temperature in the root chamber during the plant stages.
2. Each growing environment is different. The need for experimenting is crucial in receiving eXtreme harvest. Take your time, set your timer 1 minute on and 1 minute off. Then watch the program in action allowing to repeat its self a few times making sure the plant leaves don't start to wilt from lack of nutrient mist. If no sign of wilting, increase off time for a minute. Continue until desired setting is reached or 10 minutes is reached. Repeat this programming once a week for that growing week. Ultimate would be 1 minute on and 2 minutes off, for first 2 weeks of vegetative stage. Then moving to a 1 minute on and 3 minutes off after shading the growing chamber and the whole duration of flowering a 1 minute on and 10 minutes off.
4. The major benefit of an adjustable misting program is its flexibility in the growing stages of the plant. When propagated in an aeroponic chamber, newly clipped clones need to be constantly misted until rooted with a dome on top to trap humidity to the plant leaves. Once rooted, the root system needs nutrients. The nutrient interval cycles are determined in vegetative and flowering stages by root temperature. As the plant matures, the plant leaves will begin to shadow the growing chamber, reducing temperature, allowing decreasing misting time. By utilizing this procedure, the plant is allowed more oxygen intake to the root hair between feedings, achieving faster and bushier growth. In flowering, the importance of oxygen intake to the root system is staggering. Plants will go from looking beautiful to looking sick and death is inevitable from oxygen starvation.
5. Always keep a close eye on the root system inside an aeroponic chamber - even slight drying of a portion of the root system will result in tissue damage and could lead to pathogen attack.
6. Make sure to use a quality sediment free nutrient, as it's very important not to have a mister plug up. Remember that in aeroponics, the ppm (EC) in the nutrient solution needs to be less concentrated, than other soil-less systems as the roots intakes the nutrients much more easier.
Nutrient Uptake - Day and Night
Most plants take up nutrients by both day and night. With night time being the more dominant side. Commercial hydroponic growers of 'heavy feeder' crops such as cucumbers and tomatoes, experience higher nutrient uptake in the evening and into the night as the temperatures cool down the plants are able to take up more water and nutrients through increased root pressure and more suitable environmental conditions. Warmer conditions during the day, the plant will shut down photosynthesis and transpiration and thus reduce nutrient uptake, and will then feed rapidly in the evening as conditions become cooler. Calcium is taken up during the night when root pressure allows more water uptake and transpiration within the plant, carrying with it calcium into plant tissue.
The Root System
Plant roots, which end up continually submerged in a 'deep flow' or constant drip systems will commonly be long, thin, relatively unbranched, yellowing or brown in color and seem to be lacking in fine, fluffy root hairs. The roots which develop up above the flow or pond of nutrient with a mist are typically whiter in color, more branched out and often contain masses of very fluffy, fine, bright white root hairs.