Alternative Organics - Reese Tipis as Alternative Greenhouses II
As I have traveled the world I have seen all types of greenhouses. They have varied from the low cost, wood frame with plastic to the bent tubing wrapped with visqueen that may last a single season. Some of the more sophisticated were made of steel or aluminum with shatterproof glass or Lexan. In our last issue we were exposed to a new innovation based on an ancient idea--a tipi as an alternative style of greenhouse.
I was asked to follow up on two demonstration sites in Colorado. First I interviewed Greg Smith in Rocky Ford. Greg has great plans but has experienced weather too cold to do anything other than plan since the Reese Tipis were erected in mid December.
He intends in the coming weeks to incorporate drip irrigation and use a pre-emergent to prevent weeds from developing. Once that is accomplished, he plans to grow Chinese cabbage, cauliflower, two-leaf lettuce, basil and parsley along with other herbs.
His experience in agriculture has tempered his eagerness with reality. He knows that allowing too much sunlight into the Reese Tipis may cause a problem causing an earlier start with his seedlings. One of the tipis will be over a manure pit that will help "kick start" those plants or seeds that are planted in the native soil. The tipis will be located about 100 feet apart. Because Greg was concerned about too much sunlight, he wanted to ensure that afternoon shade will fall on the tipis to prevent the burning of his plants. At present, temperatures in midwinter have hovered around a low of 20 degrees to a high of 60 degrees without any auxiliary heat or heat storage media in the tipis. Temperatures in the summer are anticipated to be over 100 degrees in the day and 60 degrees at night where the outside temperature can drop to 25 degrees.
Not knowing how a tipi could become a greenhouse, I envisioned that the heat would rise up and out of the top of the tipi. However, that is not the case for the modified tipis. Although the tipi design has been around for hundreds, if not thousands of years, the insight and creativity of Richard Reese have added two important components that includes a second wall that is 6 inches inside of the outer wall and that acts as an insulator to the outdoor temperatures while coming in contact with a heat-saving false ceiling, or cold cap, that keeps the warm air in the growing area and insulates the ceiling. And like a winter hat that is not needed in summer, it is easily adjusted to control the venting or completely removed to allow relief from the high temperatures that could occur in the summer.
Further, Greg placed straw around the base of the outside of the tipi, that is also staked down for air tightness and further reduces exposure to the elements. Later, supplemental heat may come in the form of portable propane heaters that would not be vented.
Greg had some difficulties with the LaCrosse Technology WS-8610 Data Logger with three sensors that was coordinated by ChroniTech.com, one of our advertisers. Greg called the 800 number of the LaCrosse Technology customer service department, which got the problems resolved. Greg was already experienced with older and discontinued LaCrosse Technology equipment and recently upgraded to one of the LaCrosse Technology WS-2315 Professional Weather Stations. The combination of this equipment allows the WS-8610 to monitor temperature and humidity in three locations wirelessly. The WS-2310, or any of the Professional Weather Stations, adds wind speed and direction, rainfall (not too important in Colorado), along with barometric pressure, indoor and outdoor temperatures and humidity and can be used wirelessly or connected with modular connectors similar to telephone cords. The WS-2310 and WS-8610 are separate systems and do not communicate with each other, but each can be connected to your computer to build Excel databases of your history along with positing it to your Web site if desired.
Richard Reese also installed two tipis at Steve Cole and Audrey Liu’s farm in Alamosa, Colo. One is over a hot bed with deep watering provisions, whereas the other is intended to be more conventional. Organic compost will be used as needed. Steve and Audrey are also being sent a WS-8610 to monitor their tipis. ChroniTech.com is providing two WS-2310s for the UniMORF Research Facility where one will be used to monitor the Reese Greenhouse Tipis at that location. They may also provide an inexpensive, UPS-shippable geodesic solar dome for testing. The proposed geodesic dome is in sharp contrast to the expensive British greenhouse domes I viewed while traveling in the UK.
Steve indicated that he has observed a 35-degree F temperature differential between inside and outside of the tipis. Steve and Audrey have established a history with a conventional 1,500 square foot cold frame greenhouse that has provided them with a foundation of experience in their use. He is also admiring the technology of one of the nearby community adobe greenhouses which also reaps the benefit of warmer soil four feet below the surface by being dug into the native ground. He likes the ingenuity of the Reese Tipi because it is smaller and easier to heat and manage. He anticipates that his growing season may be extended by as much as two months on each end of the season. The acid test will be to see what is actually realized vs. planned.
Steve’s concern for the bad wind storms in his area necessitated his positioning of the tipis with the door on the east side. The tipis are more oval than round which enhances their stability as Native Americans discovered long ago. Even today we recognize that the circle and the oval, along with the triangle, are our strongest and most economical geometric shapes, much more so than the square and rectangle.
Steve will be growing tomatoes, peas, squash and golden bamboo. One idea Steve is considering is insulating the back side of the tipi with some type of insulating bats, packaging popcorn or other materials that could minimize the need for supplemental heat and reduce the heat loss at night. Richard Reese advises against using any organic materials in this application, like straw or hay, because rodents will nest in the straw
and dine on the fresh fruits, vegetables and other vegetation available in the greenhouse.
Richard also clarified that the exterior and interior panels of the Greenhouse Tipis are composed of one of two types of materials provided by Odin International/Thor Tarp Division. One is the DuraShield 6000 ASFR, which is 6.5 mils in thickness and is frosty-clear. The other is ThoroShield 950, which is clearer and is 10.5 mils in thickness. Both have a high resistance to tearing due to the reinforcing scrim (like reinforcing threads) placed uniformly throughout its surface and laminated between the two layers of high-density polyethylene sheets containing high levels of UV inhibitors and thermal stabilizers.
In our next issue we will update the planting process as well as introduce the installation of the INOV8 furnace that will be used to heat some of the greenhouses in the demonstration project.