YOU ENTER THE GROWING ROOM at 6 am. It is dark and the atmosphere is buoyant. The first thing you hear is the clicking of the fertilizer proportioner, then almost instantly the room is enveloped in a cloud of fog and mist. Every plant is completely saturated. Based on the lush growth and abundance of flowers, they obviously have found a home to their liking. They flourish in a simulated tropical rainforest in a former garage in a town house on Long Island.

Many orchid enthusiasts fear to expand beyond a limited collection only because they are unable to expend the time needed to provide for the day-to-day functions of watering and fertilization. Or they feel they would be unable to travel for more than a few days at a time without jeopardizing the health of their orchids.

Fortunately, these functions can be fully automated. With some experimentation and persistence, it is possible to assemble a water-and-fertilization-delivery system that needs only casual monitoring and attention once it is set up. It can offer a much more consistent and dependable job of delivering water and fertilizer to plants than many growers can provide manually.

The heart of such a system is a waterdriven piston-type fertilizer proportioner such as the Plus made by Dosamatic, Inc. These units cost approximately $250 to $500, depending on flow capacity.

The most significant advantage for these nonelectric types of units is their ability to deliver precisely metered dosages of liquid fertilizers (they can also be used effectively to apply fungicides, bactericides and insecticides) even at low pressures or flow rates (they will even operate effectively at flow rates as low as 1/3 pint per minute).

The following is a brief description of how these units operate. The proportioner is positioned in line after the backflow preventer and water timer. A water-pressure-driven piston moves up and down whenever the water flows, pulling a secondary piston that accurately injects the prepared solution through a mixing chamber to the outlet of the unit. Because of its volumetric operation, the proportion of solution to water remains constant, regardless of variations in water flow or pressure.

There are much less expensive and simpler units available, such as the "Siphon mixer" by Hyponex (which is simply a fitting placed on the water line with a tube that is placed in a container with pre-mix). I was unsuccessful in getting it to operate with a backflow preventer and timer without a large volume of water with high pressure and even then the results were erratic. Other products are "Add it" or "Grow pro" by TFS Systems, but they have several disadvantages. They operate at only one dosage, the dosage is only accurate at one flow rate or pressure (which may be difficult to measure) and they require a much higher flow rate to operate at all.

No special skills are required to set up a system. Carefully determine the proper size unit for your application and additional fixtures, piping and equipment that are necessary. Draw the system on paper before purchasing the materials. Assemble all supplies before beginning.

The system outlined below is one of two that I utilize in an indoor growing area in a garage with two 1,000, two 400 and one 250 watt HID lights (which was described in a previous article on HID lighting in the November 1993 issue of the A.O.S. Bulletin). The system has been in use continually since April 1991. It consists of a backflow preventer (this is important when you are connected into your household drinking-water system), a Gardena water timer, a Plus by Dosamatic fertilizer proportioner, about 30 feet of schedule 40 plastic tubing (which I prefer because it is threaded so it is much easier to assemble or easily take apart and reassemble into a different configuration, and is available in many different sizes), approximately 30 mistheads of various sizes, a "Y" line splitter with individual shutoffs, and end caps at the end of each line. My favorite misthead is the "Fogg-it" superfine: these are set about 2 1/2 feet apart.

My orchids are grown primarily in open baskets, or on tree-fern or cork plaques. Due to their ability to dry quickly, and the intense light and heat provided by the HID lights, they are misted for two minutes every 60 to 90 minutes one to three times a day. (In the last six months I have switched most of my mistheads to "Foggit" superfine, which can saturate the plants quickly. When I used lower-capacity mistheads, six shorter cycles a day were necessary). The first misting cycle is at approximately 6 to 7 am and the last never later than 10 am to ensure that everything is dry when the lights go off (6:30 to 8:30 pm).

Four ounces of Dyna-Gro 7-7-7 and 4 ounces of Dyna-Gro Magpro (a blossom booster) are combined with 5 gallons of water with the Plus by Dosamatic set at 100:1, resulting in a weak fertilizer solution. It takes approximately two to three weeks to use up this solution (depending on the number of daily mist/water cycles). After the fertilizer solution is depleted, I let the system flush for several days with water only to cleanse it and leach accumulated salt residue on the plants. Next, I make a solution of I gallon of water and 1 ounce of Dyna-Gro ProTeKt (a potassium and silicon formulation that hardens the plants and helps provide increased resistance to disease and insects). When this solution is used up I flush again with clean water for two days and then begin with the fertilizer premix again. This schedule has been followed for the last three years. The only variation has been in the number of daily misting cycles, which are decreased in the winter when many of the plants are resting and increased the rest of the year when most are in active growth. Some of the mistheads are closed to create an area that is not misted for plants that require a dry rest period.

In the Spring of 1994 I set up a second system utilizing the new Plus by Dosamatic, which is now even easier to assemble because it comes with adapters for several different sizes of piping. It is set up in the same configuration as the original system and also is run at 100 to one with the same fertilizer regimen. This water-delivery and fertilization system is used when I summer my plants outside. It is similar to the one described above except that I combine the mistheads with a drip system to water plants in containers or pots. I have been satisfied with the Dosamatic units; they have never malfunctioned in any way and the company has been cooperative in providing technical support for determining flow rates.

Whenever I go on vacation or away on business, l mix a full 5 gallon premix of fertilizer solution that will last about 2 1/2 weeks at two misting cycles per day. When the premix runs out, the system will deliver plain water until I return. Since the plants are fertilized almost continuously when I am home, an occasional week or so without fertilizer does not appear to set them back at all.

I have been using Dyna-Gro for four years and have been satisfied with the results. I particularly like the ability to mix more than one formulation with no problem of their coming out of solution (do not mix the two formulations together at full strength; put the water in the container first, then mix in each fertilizer formulation). A formulation with a broad spectrum of trace elements is recommended for proper growth.

I use a utility pump on a timer that follows the misting cycles by 15 minutes and runs from one to two minutes to drain off most of the excess water. The rest evaporates by nighttime. The room is constructed of cedar planking and ceramic tile and needs only occasional cleaning to keep the algae under control.

An important key to ensuring success is to experiment with the timing between cycles while closely monitoring your plants, particularly if you are growing in pots, to see that those plants needing to dry out in between waterings are doing so. Make sure the batteries in the timer are fresh; they last six to nine months depending on the number of watering cycles, but I change them before a trip.

This type of system is flexible. The (Gardena timer is capable of a range from one cycle every seven days to six variable length cycles every day and each cycle can vary from one minute to 59 minutes. It could consist of many different types of misters or drip emitters or combinations of both. It can be used in an indoor growing area, outdoors or in a greenhouse. If you have been frustrated about expanding your own collection because of time constraints or fear of being tied down to a heavy maintenance schedule, this could be the solution.

Many of the items necessary to construct an automated water and fertilizer delivery system are available from Charley's Greenhouse Supply (1-800-322-4707), Dosamatic (1-800-344-6767) and Dyna Gro (1-800-365-4769). Other items or alternative brands may be obtained through plumbing or lawn sprinkler suppliers, or at local garden centers and hardware stores.