The hydroponics community has embraced Emerald Harvest as an authentic reliable source of valuable indoor gardening advice, information, and technical know-how. Henceforth, we’ll be publishing common Frequently Asked Questions from our hydroponic gardening community every other week. Browse through this week’s FAQs and learn more about your passion with simple, easy success.
- Will the nitrogen source affect my pH?
The source of nitrogen in your fertilizer changes the pH of the medium you are growing in. When the nitrification process alters ammonium to nitrate, hydrogen ions are released and is one of the causative feature leading to acidification. So nitrogen sources (fertilizers, manure, legumes) containing or forming ammonium-N will augment soil acidification, unless all the ammonium-N is absorbed directly by plants. Also, when nitrate-N is leached, basic cations, such as calcium, magnesium, and potassium, are leached in association with the nitrate. The nitrate-nitrogen and cations move out together, and as these are removed and replaced by hydrogen ions, soils turn into more acid.
- What’re Mycorrhiza fungi and why is it so important?
It is a symbiotic association between a fungus and the roots of a vascular plant. These fungi are living organisms live with the plant, sourcing a continued nutrient supply for its entire lifetime – a truly sustainable plant nutrition solution. In exchange, the plant provides carbon and sugars to the fungi. Not unsurprisingly, 90% of all land plants employ this relationship to enhance their own root system’s capacity to deliver nutrients.
The benefits to your plants: mineral exchange, absorption of water, disease resistance and resistance to toxicity.
- What do I do once the sex of my plants is known?
Identification of a plant’s sex is carried out to distinguish males and females within the grow. This detection is essential since the males do not produce trichomes which are a standard feature within any female flower. These trichomes are the main source of THC, the primary cannabinoid responsible for the psychoactive effects. Thus male plants do not constitute a reasonable target to invest the resources like nutrients, space, and light. Even with the absence of trichomes, the presence of male plants in the cultivation presents a danger to the final yield. The male flowers are capable of producing pollens targeted to fertilize the female flowers whereas unfertilized marijuana buds are a more potent source of THC. In contrast, a fertilized female flower invests most of its energy in developing the seed rather than in producing more THC. The above reasons are the primary force behind the general approach to knock off the males. These plants are usually discarded or plucked to prevent pollination.
- Can I force my plants to determine sex, and then revert them back to the vegetative stage?
Many times, plants are forced into the flowering phase for early identification of their sex. This transition is done by putting them under a 12/12 – light/dark cycle. Once the plants have shown the appearance of pre-flowers, they are then ‘re-vegged’ by reverting to the 16/8 – light/dark cycle. However, this technique is not recommended due to massive physiological changes that take place in a plant’s body. When exposed to regular 12 hours of dark period, plant within their tissues, begin to accumulate optimal levels of hormones. These hormones which after reaching a required limit start the flowering process in plants. In this case, switching back to 16/8 light cycle can force the plants back to the vegetative phase at the notably slower rate. The time needed for the amount of hormone level to subside lengthens the overall grow cycle; thereby delaying the harvest. At the same time, the whole process puts tremendous stress on the plants, which in most of the case causes the plants to stretch. As the time required for identifying sex through the natural flowering process is much lesser than the course of forcing them to flower; this particular method is usually accepted to be non- viable.
- Is molasses used in DWC system?
In a DWC system, the nutrient water is in a static condition, and special care needs to be taken to prevent breeding of unwanted organisms. Use of molasses in a DWC system is often not recommended, due to its ability to settle down at the bottom of the scheme. This stay gives rise to a breeding ground for many harmful bacteria and algae; hence resulting in a lot of undesired effects. However, molasses can be used in a DWC system; given that few precautions are taken and preventive measures are followed. The maximum amount of molasses allowed for a DWC system is one teaspoon for a gallon of water. The molasses needs to be dissolved properly before adding it to the plants; to prevent any aggregation of solid particles in water. Molasses is recommended to be used only in the late stages of flowering before the final flushing. The water needs to be changed more often when using the molasses; as bacteria growth tends to be higher in such solutions. Thus reservoir temperature and oxygen concentration should be in complete control. Temperature below 700F is often maintained to restrict bacterial growth; while the addition of beneficial bacteria produces competitive stress among the wild ones, thus limiting their amplification. Use of molasses successfully in a DWC system is not uncommon; however, the precautionary measures are imperative to ensure the safety.
- Which of this is best-NFT/flood & drain?
In a hydroponics set up, systems like NFT and ‘Flood and drain’ shows substantial similarities in their functioning and the end results. However, there are specific areas where an individual system, score much better than the other. Electricity use: As NFT involves a continuous flow of nutrient solution through the built-in channels; power is being consistently utilized. This is not the case in ‘Flood and Drain’ system, as periodical flooding of the nutrient solution takes place; which used far less electricity than the previous method. Nutrients Availability: NFT presents a comprehensive method of nutrient supply with the continuous provision of nutrients and oxygen. As a result, growth rates were observed to be better, when compared to a similar setup with ‘Flood and Drain’ method.
Maintenance: ‘Flood and Drain’ system is much easier to maintain than the NFT system. In NFT, failure in any component such as pump, timer or electricity can result in disaster. However, a ‘Flood and Drain’ system can be kept maintained in such a case with manual flooding of the nutrient mixture. The choice between the two options, however, is largely influenced by the personal choice of a grower and the type of cultivation one is practicing.
- How do I manage my excessively tall plant during flowering? Will the size have an effect on my buds?
You can manage or limit marijuana plant height by using the following methods:
1. Light Intensity- Plants stretch because gibberellins (plant hormones) promote longer and quicker cell growth between the nodes when plants are exposed to low light. To prevent this, make sure you have adequate light for the area in which you are growing. Keep the lights as close to the tops of the plants as possible without burning them. Maintain proper plant spacing so that all of the branches are under the direct intense light. To be sure you have enough light, you might consider purchasing alightmeter.
2. Air Movement- Oscillating fans in your grow room simulate a breeze moving the leaves and stems. This movement disrupts plant cell elongation, causing the cells to exchange length for thicker cell walls. The plant is making natural adjustments to stand up to the breeze so that the first big wind does not flatten it. As an added benefit, oscillating fans help stir CO2 up off the floor and reduce pest problems.
3. Temperature- The growth activity of many plants, including marijuana, is affected by temperature differences. If the temperature during the day (lights on) is lower than at night (lights out), this is called negative differential or neg. diff. You can use this to keep your plants short and stocky by increasing the temperature during the dark to a few degrees warmer than the light period. Be careful not to overdo it: a five-degree difference is a plenty. Some strains will respond to neg. Diff. More than others, depending on the climate to which the landrace is accustomed. You need to be keeping track of temperature and humidity anyway so make sure you have a good thermometer and humidistat.
4. Topping- Topping marijuana plants helps to keep them short for two reasons. Firstly, because you have removed at least some of their physical height(It is not efficient to let your plants grow tall and then cut the tops off to make them short again, but it does work). The better reason to cut your plants is that auxins (plant hormones) collect in the tips of the leading shoots and drive continued growth. When you pinch these tips off, the concentration of auxins is redistributed to the tips of the other branches. By dividing these auxins among many branches, you can promote shorter, bushier growth.
5. Training- Branches and tops can be pulled down and forced to grow horizontally either with trellis netting or cages. Low-stress training is not a skill you will learn overnight. You will likely break some branches before you master the skill. Not all garden setups easily accommodate heavy training. If it is the only method you use to control a height problem, you have your work cut out for you.
6. PGR: several plant growth regulators (PGR’s) to help monitor the height of various ornamental crops.