Article 2-3 Effective Use of co2Good gardeners say great things about C02. There's no question that increasing carbon dioxide levels in the garden has tremendous potential for creating faster, more productive crop plants. The trick is to use C02 wisely-knowing when and how to add C02 for maximum results. The first step is to create such great growing conditions in your garden that your crops will benefit from extra carbon dioxide! Careful attention to light levels, temperature, air flow through the garden, exhaust fan capability, air intake, crop spacing and nutrient supply will result - in a first class garden with healthy, vigorous plants; ready and willing to take up and use extra C02 efficiently. Overheated, crowded and bug-infested plants are so busy just trying to survive that adding C02 would be wasteful. Whip your gardens into shape first-then plan when and where to add C02 to get the greatest benefits. Our plants go through several growth stages during their lives seedling/cutting stage, transplant, green growth, transition (to flowering and crop production) and production stages. Each growth stage has its own "cultural requirements" seedlings need different light levels and fertilizer strengths than established crop plants, for example - and extra C02 is more useful during some growth stages than others. Generally, adding C02 helps the most during periods of rapid growth, but researchers have discovered some surprising and useful facts about carbon dioxide's effect on specific stages of growth and how extra C02 early in a plant's life brings unexpected benefits months later! And once again, it was a Canadian team of University researchers and commercial growers who broke new ground in effective uses of C02 enrichment. C02 APPLICATION: The Canadians discovered that adding C02 to plants at the seedling-rooted cutting stage - for about two weeks - produced two benefits: faster early growth and greater final crop yield, even without extra C02 during green growth or crop production! This is useful information for hobby gardeners since a little extra carbon dioxide for rooted cuttings and seedlings can help plants so much. If you use tall, clear covers over your baby plants, release a little C02 under the cover to raise the C02 levels to about 1500 PPM. Remove covers to let in fresh air after a few hours, and be sure plants have only fresh air (no extra C02) during dark periods. The two-week period leading up to transplanting is the most effective time for this C02 technique. If you are already using C02 for other purposes, try treating your 'small fry' with this proven growth and crop stimulator. C02 APPLICATION: Adding carbon dioxide during transplanting stage is not recommended, since plants are adjusting to new growing conditions and can make do with regular C02 levels in the air. C02 APPLICATION: Once plants are 'established' in green growth stage (full light levels, full strength fertilizers, spreading roots and new top growth), it's time to consider adding C02 to your rapidly-growing green plants. Your decision should be based on the length of time your crop will be in green growth, as well as an impartial evaluation of the garden's growing conditions. Plants with a long green-growth period (30 days and more) would benefit from C02 enrichment, growing to the desired size more quickly. Growth hormone used along with extra C02 and increased food strength, results in faster, healthier green growth plants. C02 APPLICATION: Some crops, called 'long day plants', produce their crops during summer, while continuing to put out new leaves and stems-tomatoes and roses are typical long-day crops which benefit from supplemental C02 right through green growth/crop production stages. These plants do not go through a separate transition stage like short-day crops, so additional C02 can be applied (during the light cycle) through the life of the plants. C02 APPLICATION: 'Short-day' crops have a definite 'transition' stage before flower or crop production begins, affecting C02 applications. (Short-day plants produce green growth during spring and summer, and flowers and crop in autumn, responding to the longer nights by beginning crop production. Chrysanthemum and hardy hibiscus are examples of this category of plant). Since C02 is most useful when established plants are actively growing, shut off your tank until crops pass through this transition stage and save the extra C02 for use when crops begin producing flowers. Holding off on extra carbon dioxide while plants go through the transition from green growth to crop production should help keep plants bushy and compact while they decide what they're supposed to do next and reduce 'stretching' problems so common to the early transition period. In fact, if your short-day crop has a history of stretching, cut off the extra C02 two weeks before the end of green growth stage. FLOWER AND CROP PRODUCTION Once crops are 'established' into crop production stage (full light levels, full strength food, plants actively producing crop) resume C02 enrichment - if all goes well you could consider increasing the nutrient strength gradually for periods of maximum growth during this stage. As growth slows and crop is finishing up, cut back on C02. FINE-TUNING THE HORIZONTAL C02 DELIVERY SYSTEM After 7-14 days, your crops will tell you: how many plants are gaining from the extra C02. How much it is helping your crop plants. You can reposition oscillating fans, add C02 airlines to more oscillating fans, or increase C02 flow rate if growth rate is uneven or some plants need more C02. Usually growers become very enthusiastic about adding C02 at this point, since they can see how it's helping their gardens. If little or no effect on growth is seen, check growing conditions for limiting factors, high garden temperatures, poor air movement, bugs, disease or incorrect nutrient mix all interfere with C02 uptake and growth. C02 GENERATORS The C02 generators we use for carbon dioxide enrichment are very efficient burners of propane or natural gas. By completely oxidizing the fuel, the generator gives off pure carbon dioxide - and lots of heat and water vapor! Growers planning to install C02 generators in their gardens should anticipate having to deal with excess heat and humidity from their new equipment. We approach this problem a number of ways. One method involves placing the generator in a remote location and moving the C02 through ducting to the air intake where it is delivered to the crop by oscillating fans. A fan attached to the duct draws the C02-rich air from the generator, helping to dissipate heat and causing some of the water vapor to condense inside the duct. Sloping the duct slightly and placing a tray or bucket at the end to catch condensation run-offs helps in removing condensation from the duct. Another method is to suspend the generator overhead above the garden and use timers or control systems to supply C02 for brief periods during the light hours. All fans are shut off, the C02 generator goes on, carbon dioxide drifts downward onto the garden, and when the generator shuts off (by a timer or thermostat) the fans are turned back on to cool the garden. The disadvantages of this method are: |
|
Hydroponics University is brought to you as a service of Simply Hydroponics and Organics On-line as part of our consumer education program. We welcome your feedback, your ideas are what makes this site work for you. Click here to CONTACT US with any ideas or questions. |