If all the plants are short, then row orientation is irrelevant. Taller plants cast a shadow, and the footprint of that shadow - and its movement throughout the day - needs to be taken into account. I use both N-S and E-W orientation in my gardens. Whenever possible, I place the tallest plants in the North side of a bed, in E-W orientation. This results in a zone of permanent shadow, so E-W orientation in the middle of a bed will result in loss of usable space. Because of that, I often place paths in that location, or a block of corn. (And BTW, those shaded paths are most welcome in the dog days of summer.) If I use tall trellises in a N-S orientation, then I try to grow plants of medium height adjacent to them, so that shading will be less of an issue. These might be shorter trellises of cucumbers, or caged tomatoes. In areas with hot summers (such as when I gardened in SoCal) some plants can benefit from being planted on the East side of tall crops, so they will be protected from the afternoon heat. Tomatoes really seemed to like that arrangement, it caused a major reduction of sunscald. If you are planting a lot of tall crops, then the amount of shade increases, and wider row spacing is required to compensate for it. I often plant adjacent 6-foot trellises for various beans & gourds. With E-W orientation, the plants get full sun all day, but only on one side; and rows need to be spaced 3 1/2-4' apart. With N-S orientation, plants get equal sunlight on both sides... but the rows will shade each other both early & late in the day. If spaced too closely in either orientation, then the plants will be top heavy late in the season, with little growth - or yield - in the shaded zone. Shebear brought up a good reason to use tall crops, which is as wind breaks. I plant tall trellises on both the North side (running E-W) and the West side (running N-S) of my gardens, to protect from cool NW winds. Here in the North, heat-loving crops (such as okra, eggplant, and watermelon) do better in those protected micro-climates. Furthermore, those outside barriers usually sacrifice themselves to protect the interior from the first frost. I also use tall trellises as baffles, to block or re-direct pollinators for seed saving. In various locations, both N-S and E-W rows serve that purpose. So really, the question of row orientation is dependent upon your gardening philosophy. If you have limited space, then using only short crops - or a row of tall crops on the N side - is the best utilization of space. Rows can be closer together, so you can grow a greater variety... and orientation won't matter. But if you have more space, enjoy picking without bending over, or prefer to grow varieties that climb (as I do), then just consider that planting tall crops is planting shade, and plan for the shadows accordingly.

I just wanted to post that I was out at the National Arboretum a few weeks ago. The large Q. acutas looked like they sustained some damage from teh past winter. Some twig and a few branches died back. Sad to see. But they will certainly survive. The Q. salicina looked like it had NO damage at all surprisingly. I have never seen acorns on them. Interestingly the Q. phillyreoides had some acorns. No apparent dieback. They all looked rather shrubby to me and not large single trunked trees. L. henyri and Q. myrsinifolias looked just fine. Q. glauca specimens at the Arboretum have all had a rough go of it over the years. Numerous diebacks. Pretty pathetic. They should really not be grown up here. But maybe they got some northern provenance stock that they wanted to try. I didn't see where they were from. Unrelated, but all the hollies looked great. Even Ilex latifolia. The Ilex latifolia in my yard looks great as well. No apparent winter damage. A small amount of leaf spot but overall I was very pleased. This post was edited by dave_in_nova on Fri, Oct 17, 14 at 10:33

With the plants you overwinter, do you partition off only the part with the overwintering plants and heat it, or do you heat the entire greenhouse? Unfortunately, i have to heat the entire greenhouse. With the exhaust fan on one end of the GH and the vents on the other end of the GH, i would not be able to regulate the temperature. Is your foilback wall permanent or do you put it up for winter and take it down when the weather warms up? I have tried it both ways, i just leave it up now. I'm not gaining or loosing any light either way and i dont have to worry about storing it somewhere else. What percentage of light does your shadecloth block? Honestly i dont know, it was used when i got it. I did'nt know much about shadecloth at the time. I would guess it is around the 50% mark. I had bought some remnents that were 60% and it was darker then what i had already. Can you shade the greenhouse enough to use it at all in the warmer months, or does it just retain too much heat? During the cooler months, it is alot easier to pull the heat out without the use of shadecloth. Mainly because the outside air is much cooler and does'nt have to exhaust as long. I usually take the shadecloth down during the winter months. during the summer months,even with shadecloth it will still be 100+ degrees inside with the exhaust fan running. It is pulling warm air inside(slightly cooler) then the inside air.there is not much you can do in it in the summer. According to the size and shape of my greenhouse i have the exhaust and vents sized right. In the winter months, I hope to set up a cold frame and grow some cold-season crops that overwinter well. I may not heat the greenhouse at all except once I start raising seedlings in it. I would try and go that route if at all posible. unless you have money to burn, i would'nt run the greenhouse when not needed.Not that i have money to burn.Usually the only time heat is needed is cold clowdy days and nighttime. When you said your greenhouse runs east to west, do you mean your 16' wall faces the east and the west or that the 48' wall faces the east and west? My 16' wall faces the east. that is why i said i leave the foilback insulation up. I dont loose enough sunlight on the north side to worry about. My greenhouse runs east-west, so the shorter 12' wall faces east and west and the 24' wall faces north and south. That is the way mine is set up also. I have limited flat land also, and water and electricty was another determining factor in why it had to be set up like that. I dont remember if i mentioned it or not, but i also ran a frost free water hydrant inside the GH. I dont have to worry about frozen water hoses. I also have an old kitchen sink on a stand inside also. It come in mighty handy when it is freezing outside and you need to rinse something off. One of those mud room/utility sinks would not take up much room, you might think about that. And for all of you thinking I am crazy to be mentioning a second greenhouse when the first one isn't even finished yet....don't blame me! Tim put the thought of a second greenhouse in my head by saying, several times, "the next greenhouse that we build, we'll......blah, blah, blah....". So, even though we aren't through building the first one yet, he's already thinking of what he might do either the same or differently the next time. How can a gardener's heart not rejoice when the non-gardening spouse is already planning a second greenhouse? I know 12x24 will look big while it is empty, once the plants start filling it up, you will want another and another.... I turned one of those portable carports(12'x21') into a Gh in town at my business to use as a holding GH.So i have a pretty good idea of the space you have available. I used some leftover GH film to cover it. If i can remember to take the camera(if i can find it)i will post some photos of how and why i did it the way it is.It really turned out nice. I wished i knew how to use a different color when answering back. Robert

Hi Mabb From my perspective you need to understand several things for this to be successful...it works in nature...on the otherhand a garden setting is a long way from a natural setting...fences for example prevent a lot of air flow and make your garden prone to fungal attack As far as soil pH goes ....most vegetables do pretty well in a general range of pH levels but do not do well in extreme pH soils....so you get leeks and onions doing well enough in the same soil as potatoes In nature you find plants that have non airborne seeds having to grow in the space their parents did and that seems to work...I would suggest because the decomposed plant material stays on site and thus the nutrients in that are ready to supply the new generation of seedlings...a reason why I advocate sheet muching when ever one feels the compulsion to "weed" I have also found that pests and diseases (seem) to be pretty well nonexistant when the flora is of greater diversity...it is much harder for pests to find and move from one host plant to the next in a "jungle" of diverse plant types I think that the concern that some people have of weeds using water at the expense of vegetables is also misplaced because I feel that evaporation levels are lower when the moisture is trapped under foliage (as in a rainforest) and the sunlight cannot reach the soil (where it kills off soil micro-organisms to the detrement of soil fertility) The greater energy conversion from sunlight to plant matter means an increase in soil fertility over an extended period Fukuoka suggests that soils do change over time (in his experience it takes about 10yrs.) and that one finds a change in the success rates of some plants when the soil has had one type of plant in a succession in one area...this can be beneficial of course but when diversity is maximised and mass is also maximised at the same time you can only gain The greatest problems I can envisage is that of toxic root exudates which some plants have and also that of autotoxicity which occasionally occurs It all sure beats buying in your fertility cheers Peter