For people with a passion for gardening and fresh tomatoes with pesto, winters even in southern Arizona can seem long. Most of us read gardening magazines and seed catalogs, struggling to restrain our planting impulses through the cool months.
However, for those fortunate enough to have a solar greenhouse attached to their homes, fresh tomatoes become a year-round delight. They sow flower and vegetable seeds in fall, and gardening becomes a twelve month activity.
This new series will introduce you to many facets of greenhouse gardening, from design considerations and construction tips, to the management and use of a solar greenhouse.
For many, the cost of a greenhouse may be a primary concern. Don't let money stop you! I once designed a $500/five-year greenhouse plan for a woman on limited income. For about $100 a year over a five year period she constructed her solar room addition. Admittedly, this was a number of years ago, but even today a small usable greenhouse can be built at a fairly low cost, then improved and modified yearly until it becomes a comfortable, productive room.
The first question to ask yourself is: Do I really want a greenhouse? Your initial response will probably be a loud "Yes!" but take some time to reflect on your lifestyle, your energy, and other commitments. Do you travel in winter? Do you enjoy or maybe even need a few months off each winter to relax, work on other projects or pursue other interests? Are you willing to commit time and energy each week to keep your greenhouse clean and bug free?
If you're not sure you're really ready to do this, don't! A solar greenhouse isn't for everyone. I've seen more than one that's been turned into a storage room or ignored and left to deteriorate.
The second question is: Do you have adequate space to attach a greenhouse to your home in an area that receives more than six hours of sun on winter days? A solar greenhouse will not perform well if it's shaded by nearby buildings, fences or tall pines (or will be, when those pines grow up!).
The best site for an attached greenhouse is the south side of your home, although the east or west side could also be used. The south side of a greenhouse needs full winter sun. Trees and houses cast long winter shadows, shadows at least twice the height of the object creating the shadow. So when you check a potential site remember that a 20 foot tree south of your envisioned green house will create a 40 foot winter shadow. Trees and houses to the southeast or south west of your future greenhouse cast shadows even longer.
Next month I'll give you detailed information on how to evaluate your site. If you can't wait that long, go to the library and check out either The Solar Greenhouse Book edited by James C. McCullagh or The Passive Solar Energy Book by Edward Mazria.
Master Gardener Cathe Fish and I both worked for some time with the Arizona Solar Action Team conducting solar greenhouse design, use and construction work shops around the state. With a little prodding, who knows? Maybe there's a greenhouse workshop in the future!