Perhaps every gardener wants to control his own destiny -- and that of his plants. But he can only do this by controlling the environment.

Greenhouses are designed to do just that.Temperature remains the most limiting factor to growing plants in our area. Plants that thrived outdoors during the summer must succumb to Mother Nature's chills and either go dormant or, worse, die out.

One greenhouse owner who has done his best to modify the condition is Eldon Kearl. My friendship with him started with our mutual interest in growing plants out of season. While I developed a rather plain and passive design for mine, Eldon decided that hecould build a better greenhouse.

Like all good carpenters, he started with the frame. Because the wood gets wet and is likely to decay, he selected redwood, which is naturally decay resistant. Designing and locating the greenhouse was not a matter of mere chance but a scientific process to maximize the light by avoiding the shadows. Eldon managed to select the exact location in the yard where the greenhouse was in full sun, even during the winter solstice.

Eldon is one of the most innovative hobby greenhouse owners I know. While most are content to tend their greenhouses every day, opening and closing vents, turning the heater on and off and performing many other tasks by hand, Eldon has automated them. When temperatures get too warm, on come the fans. If it gets too cold, the gas heaters fire up to warm the plants. Likewise, the lighting, fertilization and much of the watering are all automatic.

"I automated as many things as I could," Eldon said. "While I enjoy my time in the greenhouse, my busy schedule means I have to have a building that will take care of itself, if necessary. Taking the time to set up mechanical and electrical equipment was fun, and it has worked well for many years."

He emphasized that quality workmanship is important, so that automated equipment is be dependable. "I built my greenhouse so it met every building code that was applicable. This is very important because you are working with electricity in a wet location, and you are also piping natural gas. If these are not done right, you could cause serious problems to the greenhouse and put yourself at risk for personal injury. I had Mountain Fuel come inspect the gas installation, and the city inspected the rest. I know that using it is safe for me and my family."

Eldon first got interested in greenhouses when he started growing tomato plants. Although the plants were OK, he knew they could be better, and could be grown more easily. He registered for a hobby greenhouse class and was on his way. A model student, he learned so much that he now helps teach the class every year.

"After I attended the greenhouse class, I used that information to design my greenhouse," Eldon said. "The handouts contained all the calculations I needed to design the heating and cooling systems, and the materials to build it with, and information on how to grow the plants."

Eldon loves to grow all kinds of plants. As he watches his garden all summer, he delights in knowing that he started those plants from tiny seeds. "My favorite holiday of the year is New Year's Day, because I spend the afternoon in the greenhouse starting the plants that take a long time to grow. I don't have a telephone or television, and enjoy myself in my little paradise of my greenhouse. I grow all kinds of flowers and vegetables. I really like to find some early tomato varieties and several others that do well in Utah.

"Whether you are a novice or an experienced grower, you will learn from the Utah State University Extension class. I have been a part of that class for more years than I can remember. I would highly recommend it anyone thinking of building or operating a hobby greenhouse."