Zone 8: Growing pains and how to avoid them

(page 3)

HID light growing is a proven effective method which has been in use since the Japanese developed hydroponic gardening shortly after World War II. However, in order to produce photosynthesis, palms also need water, CO2 and warmth. Water run off problems can easily be solved with inexpensive plastic tubs and plastic gutter systems which cost little, actually enabling the placement of a fabulous palm growing environment within an enclosed garage. Ventilation to provide CO2 is more of a problem. Traditionally, HID light growers have ventilated their growing areas with conventional ventilation systems such as mechanical draught exhaust fans which provide air exchanges in a matter of minutes. For growing palms, the air exchanges occur far too quickly, removing the warm air, and if it is cold outside, replacing the essential warm air with growth inhibiting cold air. The palms require two things in addition to water and radiant light. They need warmth and they need carbon dioxide and they need them in combination. The operative word here is combination. If you provide warm air depleted of carbon dioxide, or if you provide carbon dioxide replenished air which is cold, you will not obtain the growth which is so critical to maintaining your enthusiasm. If conventional ventilation is used, install a fan which provides a slow air exchange such as a 50 or 60 cubic foot/minute bathroom fan and place it on a timer so that you can limit and control the ventilation. The objective is to retain as much heat as possible, but to provide fresh air containing carbon dioxide at the same rate at which the palms deplete it. A rule of thumb is to run the exhaust only once or twice a day, just long enough to provide one air change every morning and once again during the warmest period of the day (around 3:00 p.m.), but provide the second air exchange only on days when the temperature reaches or exceeds 90 degrees F (30 deg.C).

The ultimate growing system might be HID light in combination with a CO2 generator. CO2 generators have yet to be proven, but they can be purchased for two to three hundred dollars. The smallest of these units should provide more than enough CO2 for palm cultivation. A CO2 generator enables a grower to retain heated air within an encapsulated (insulated) environment, by replacing only the CO2 that is extracted by the palms, without requiring the air exchanges which trigger the excessive cost of providing nighttime heat.

Perhaps it might seem like a burdensome financial outlay to purchase an HID light and a CO2 generator, but compare it to the cost of nighttime heat which can be so expensive during the winter months. So expensive in fact, that only a few heated greenhouses probably actually exist in the Pacific Northwest for the purpose of growing palms. A saving can be seen after the first season with several more seasons practically cost free. The manufacturer s estimated life expectancy of an HID bulb is two to five years, and only the bulb needs to be replaced when it burns out. Consider purchasing an HID light the first year, while making do with a cheap bathroom fan for exhaust, and then purchasing a CO2 generator the following year. There are less expensive ways to raise palms in cool winter areas, but they are much slower and much less gratifying.

If you are considering an HID light, here are a few basics. Hydroponic growers of tropical plants have already determined that the best growing format for tropicals (including most palms, tropical or otherwise) is that the HID light be on for 12 hours and off for twelve hours, turned on once per day for maximum growth results as well as maximum bulb life expectancy. Never splash water on a hot bulb or it will explode with the potential of causing serious injury, and it is strongly urged that a protective glass cover be purchased along with the HID apparatus to prevent this risk. The optimum growing temperatures for tropical palms is 93 degrees F. (33 deg.C). Above that it has been scientifically proven that almost no palms benefit in terms of showing faster growth, although many growers strongly claim otherwise. Heat loving palms (Sabals, etc.) can be placed on upper shelves, while palms requiring cooler conditions (Ceroxylons, etc.) can be placed on the floor with other palms in between. There will be a 15 to 30 degree F. difference between the floor and the top shelf space at any given time and two max-min thermometers should be installed at top and bottom locations for determining these differences and providing the correct temperature at any given time. It is also advisable to provide a circulating fan, and preference should be given to installing a ceiling fan as they do the job of circulating the air beautifully, and they are practically noise free, a welcome relief from the obnoxious noise created by conventional circulating fans.

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