Garden & Greenhouse July 2017 Issue - Page 28

floor like pavers or flagstone. If you are stacking drums on top of one another be sure to use a strong and level surface between layers. Avoid Freezes Freezing a 55-gallon drum of water in a year- round greenhouse is rare; as this requires a very long period of freezing temperatures (which would likely kill plants). However, this can happen if the greenhouse is un-used and open through the winter. Freezing a barrel will likely break it. If you do not plan to use the greenhouse year-round (three-season growers), and live in a climate with harsh winters, you may need to drain the barrels, a cumbersome task. Thus, water walls are best suited for year-round growers. An additional tip is to leave a small air gap at the top of the barrel when filling it. This is because water expands when it warms up during the day. After bar- rels are installed in the greenhouse, fill them on site (since they are too heavy to lift) leaving a small gap at the top. Paint Drums a Dark Color Dark colors absorb more heat than lighter colors. Conventional wisdom says to paint drums black. This comes with the drawback that now the greenhouse has a large black wall, which can detract from the feeling of an open green space. Some studies show that blue or red colors absorb roughly the same amount of heat, and reflect light in the red and blue spectrum that plants need for growth. There is also the option to be creative with water barrels. The year round greenhouse at The Cheyenne Botanic Gardens in Cheyenne Wyoming, for example, incorporates tall light blue columns of water which bring both passive climate control and a beautiful aesthetic to the passive solar greenhouse. The blue color comes from a fungicide added to the water to prevent algae growth. If using a translucent con- tainer, consider using a fungicide, as algae will likely occur when water is exposed to light. Make Thermal Mass Part of the Floor Plan As mentioned above, the major drawback to large water containers is that they take up considerable room in the greenhouse. It is critical to plan the loca- tion and spacing of mass when designing your green- house floor plan so you don’t end up with too little growing room. GG Lindsey Schiller is author of The Year-Round Solar Greenhouse and co-founder of Ceres Greenhouse Solutions which designs and builds energy-efficient greenhouses for a range of growers. Visit Want ScrOG? but don’t want the hassle? Say GOODBYE to bamboo and sad, saggy trellis netting! P SCROG Pro (1 screen) 28 P SCROG 2x4 or 4x4 Optional leg clamp set* P SCROG Primary (2 screens) July 2017