The "Middle Atlantic" colonies of the original thirteen were considered to be New York, Pennsylvania, New Jersey and Delaware. We also include the District of Columbia, Maryland, Virginia, and West Virginia. The "Mid-Atlantic" is the area east of the Appalachian Mountains. The clearest picture of the "Mid Atlantic" can be seen in Rob Proctor's "Naturalizing with Bulbs". Zones in this region range from Zone 4 in northern New York State to Zone 8 south of Norfolk, Virginia. Plant cultivation information from the Mid-Atlantic forum may be applicable to Illinois, Indiana, Ohio, Kentucky, and Missouri. From the US National Arboretum in Washington, DC. Cold Hardiness Ratings for Selected Woody Plants Representative plants are listed under the coldest zones in which they normally succeed Zone Ratings -- Average Annual Minimum Temperature Range Zone 4 (-30 to -20 F) (-43.5 to -28.9 C): Acer saccharum (Sugar maple) Hydrangea paniculata (Panicle hydrangea) Juniperus chinensis (Chinese juniper) Ligustrum amurense (Amur River privet) Parthenocissus quinquefolia (Virginia creeper) Spiraea x vanhouttei (Vanhouffe spirea) Zone 5 (-20 to -10 F) (-28.9 to -23.3 C): Cornus florida (Flowering dogwood) Deutzia gracilis (Slender deutzia) Ligustrum vulgare (Common privet) Parthenocissus tricuspidata (Boston ivy) Rosa multiflora (Japanese rose) Taxus cuspidata (Japanese yew) Zone 6 (-10 to 0 F) (-23.3 to -17.8 C): Acer palmatum (Japanese maple) Buxus sempervirens (Common boxwood) Euonymus follunei (Winter creeper) Hedera helix (English ivy) Ilex opaca (American holly) Ligustrum ovalifolium (California privet) Zone 7 (0 to 10 F) (-17.8 to -12.3 C): Acer macrophylium (Bigleaf maple) Rhododendron Kurume hybrids (Kurume azalea) Cedrus atlantica (Atlas cedar) Cotoneaster microphylla (Small-leaf cotoneaster) Ilex aquifolium (English holly) Taxus baccata (English yew) Zone 8 (10 to 20 F) (-12.3 to -6.6 C) Arbutus unedo (Strawberry tree) Choisya temata (Mexican orange) Olearia haastii (New Zealand daisy-bush) Pittosporum tobira (Japanese pittosporum) Prunus laurocerasus (Cherry-laurel) Viburnum tinus (Laurestinus) (Source: USDA Miscellaneous Publication No. 1475. Issued January 1990. Authored by Henry M. Cathey while Director, U.S. National Arboretum. Edited, formatted and prepared for the US National Arboretum web site by Ramon Jordan, March 1998 & Revised March 2001. U.S. National Arboretum, Agricultural Research Service, U.S. Department of Agriculture, Washington, DC 20002. Note: USDA Miscellaneous Publication No. 1475 is not copyrighted, and permission to reproduce all or any part of it is not required.)

Hairmetal4ever, some of the information that has been the most useful to me in designing the SHCS for my relatively small planned greenhouse has come from people in the UK where the climate is definitely different from where I live in southern Arizona. My husband and I are just finishing digging the subterranean section and hope to finish that and start on the greenhouse structure this spring. Therefore, my responses to your questions are not based on personal knowledge. Much of what I understand has come from the following sites: http://www.permaculture.co.uk/articles/how-build-solar-greenhouse http://www.sunnyjohn.com/indexpages/shcs_faq.htm http://forums.gardenweb.com/discussions/1607983/subterranean-heating-cooling-system http://forums.gardenweb.com/discussions/1613384/subterranean-heating-cooling-system-continued?n=29 1. Hex2006 explained to me on one of the threads on this site how running the system at night using ouside air in the summer could cool down the underground storage space to increase the cooling capacity during the summer. This is essentially adding a means to take cool night air in underground and also exhausting it outside to drop some of the accumulated stored heat. During the day the air would come from inside the greenhouse and also exhaust into the greenhouse. 2. Definitely backup systems are a good idea. 3. One of the responses I read related to this was where the SHCS system was run in conjunction to the supplemental heat. There was a comment to the effect that it was cheaper to heat from a few degrees below freezing than from several degrees below freezing. Also, using the system to cool during sunny winter days helps recharge the system for the cold winter nights. 4. My understanding is that the temperature differential is affected by the number of greenhouse air changes per hour. This is controlled by fan speed and tube capacity. 5. The size of the system is related to the volume of the greenhouse. I will have to look up the ratio. Usually the system is under the greenhouse but my system will include some space outside the greenhouse.

This weekend, May 7, we are having our annual swap in Burtonsville, MD If you have extra winter sowns to share/swap please come on over. All details are over at the Mid Atlantic forum. Swaps and giveaways. Bring a dish to share at potluck.

Yay! I'm telling all my friends. I have such beautiful plants from the swap and Grandma's gardens are reason enough to come!