Thank you all: The most extreme (by far) chlorosis I'm seeing is on the 9th leaf Freedom tree, the rest are 3rd - 4th leaf now. I'm such a dope for not getting pic.s of the chlorosis symptoms but here is what I (REMEMBER) seeing - the cluster leaves never show any, it begins following fruit set on the new shoots (only I think) and continues on the new growth up until about mid Summer then ceases on the new growth as it peters out, it starts up again around harvest time and remains until leaf fall. I realize this may have some scratching their heads, my observations and recollections have been sub par and may therefore not make much sense. The leaves on a shoot appear destined to remain chlorotic once they have formed and never recover. I'll do a very good job this year of observation and documentation if it kills me, this is embarrassing. Fruitnut: aint our soils just dandy! My math, for what it's worth. 2.8% = 0.028, an a.f.s. of soil = 2,000,000 lbs. therefore 0.028 x 2M = 56k lb. of lime in the a.f.s.. I was aiming for a foot deep so we'll go 56k x 2 = 112k lb., 112k / 2 = appx. 56 tons/A, one ft. deep. I haven't nailed down my S amt. yet to neutralize the lime but am re-thinking the 1 ft. depth to just 6 - 7" for the first year of additions. I've seen the same comments about hoplessness but some are colored by the economic costs associated with adding large amounts of S. I take your point about pH variability in different locations. I did look at a number of pics. and descriptions of apple Fe and Zn deficiency in leaves last year and couldn't separate the 2 looking at my tree(s) it was frustrating and I figured it wouldn't be all that hard to figure out, I was wrong! Well aware of chelated iron and may go that route, my first inclination has been to correct the soil pH and lime issues in that they can cause other problems as well. CSU (and others) recommend a green tip Zn SO4 spray for Zn deficiency, I may give that a whirl this Spring on one side of the tree and leave the rest alone, or do the whole darned tree. H-man: after further reflection over the past few days I agree that I'd best not go for altering the entire soil profile down to a foot this year, probably calculate and amend for the top 6" this Spring then sample 0 - 6" and 6 - 12" next late Fall to see what happened and go from there. If I recall, the wood chips and leaves release a fair amount of Ca when they break down too. I've gone back and forth over the foliar feeding but haven't tried it so far except a very small trial on the pear tree with Fe EDTA, it burned the leaf margins and the rate and drying conditions were correct. After that experience it soured me some. The N source for me is just a matter of getting the most pH lowering for my buck while adding the N, in retrospect, ammonium sulfate has the highest CaCO3 neutralizing effect of all the N ferts., DUH. I don't expect the miniscule amount of amm. sulfate added to my soil to get the N I need this year to pack much of a punch to the pH but it's a step in the right direction, S will have to do the real heavy lifting on neutralizing all that lime. My target pH is 6.5, no plans to go below that, no real reason to that I can think of, point taken. Man I'm starving, thanks again all. there was probably more to write but the stomach has my full attention now.

[quote]R2 as we know it in America is quite low for house insulation. I used that number to allow for our test greenhouse to have 6mm twinwall on the south and south roof and some insulation on the North walls etc.[/quote] Heh, perhaps I'm just weird then, but I have metric R2 on my north wall (+parts of east and west, +underground) and about metric R 1.4 for the glazing. Metric R values are about 0.17 times US R values. [quote]I am sorry but many here with small greenhouses are infact coming as close to an hermetically sealed structure as possible. 10-20 tubes of calking... on a 6x8ft? [/quote] Well, it depends on what the caulk is being used for. I caulked my insulation on. Let me tell you, that takes a lot of caulk. Even if you seal up all of the cracks, I would be surprised if the small amount of circulation couldn't occur through things like: * The drainage system * Between panes of closed vents * Through the zipper or doorframe. Sure, a vent is a good idea. But we're talking about needing a very small amount of air indeed. [quote]Also in this thread nobody has mentioned the water. Unvented heater, sealed up as best you can, no air exchange. Adding CO2 by burning propane makes it wet in there too.[/quote] That is true. The moisture beads on the glazing and runs down to the floor; it's like a jungle in there (when I wear glasses, it's instant fogging when I walk in). I haven't grown any plants that are sensitive to moisture-related diseases before, but I've got some in the seedling stage right now, so we'll see if they complain. They're doing quite beautifully so far (I could get pictures if you like), but moisture-loving diseases like powdery mildew take some time to get established. I'll get back to you about them in a month or so and let you know how they compare to the equivalent plants grown outside this summer. [quote]stressbaby, Gladly. Greenhouse cucumber operation in Calif. with newly installed unvented heaters. After a cold winter period, severe damage was noted on the crop. Air samples analyzed showed elevated levels of ethylene and mercaptan.[/quote] Elevated *mercaptan* levels? Wow, that heater must have been doing an awful job. Mercaptans are only in PPM quantities to begin with, so if you're having measurable amounts *after* combustion, something is seriously wrong there. [quote]economic losses to greenhouse growers from ethylene pollution are reported each year[/quote] You do realize, I presume, that ethylene pollution can happen even when no heater is used. Decaying plant matter is an especially bad ethylene producer, but even healthy plants produce it (some species more than others). [quote]For an interesting thread from about a year ago, complete with more examples of problems with unvented heaters, use the search function, type "carbon dioxide" and read the posts on "plants suffering from propane". Some noted problems in other "real-life" situations.[/quote] Well, for your information, with Thanksgiving dinner, my main course was a delicious vegetarian lasagne made with a heaping handful of basil from my "suffering" greenhouse basil plants. Last night for dinner, I had pasta primavera made using some of my "suffering" tomatoes. My point? A proper installation doesn't have problems. An improper installation does. Notice how you haven't gotten into the risks of the other common hobby greenhouse heating system, electric. You know, a box of resistors with large amounts of current flowing through it, in a moist environment that usually has a metal frame, and plenty of combustables within, possibly even standing water? I read the "suffering from propane" thread before I got my heater. I read enough from elsewhere to realize that this person had an improper installation. Notice -- it only took a few days of use of their heater for problems to occur. Mine has been running for two months this winter. Note what was mentioned in the thread: "Sometimes the smell is very strong." Huge red flag right there. Properly combusted propane/natural gas has no smell. The instant they smelled it, they should have disconnected the heater -- it sounds like a leak. Note what others said in the comments trail, such as Orchiddude and trigger_m (who also provided pictures). [quote]One factor missed in this thread was ethylene.[/quote] Ethylene was already mentioned several times in this thread. Use your browser's search function; you'll find it.

Well, pdshop(5), I hope you had more success with your dahlias this year than you did last. I just wanted to add a note or two to all the advice you have already received. As I'm sure you know, there are a lot of different growing climates as well as different soils in Colorado. If you're up in the mountains near Dillon or Aspen, you're going to face very different problems from the folks here along the front range, such as a very short growing season and very sandy, rocky soils. Where I grow dahlias here on the front range, I'm fortunate to have well drained loamy soil, and my dahlias from Swan Island reliably grow five to eight feet tall and bloom profusely. I water them almost every day in the heat of the summer, and not with a sprinkler. I use a three foot water wand, hand watering and make sure that the water is directed onto the ground, not on the plants. And I don't just wet the surface, I give them a good soaking. Of course, if you have much clay in your soil, you wouldn't want to water as much as I do. Another thing that I suspect aids with my success--I dig the soil pretty deep, maybe ten inches, in the spring before adding my fertilizer and any amendments, and then mix them in well with a rototiller. There are people here in Colorado who grow big, tall, thick dahlias, you know. Surely there must be some neighbors somewhere around you who grow dahlias with some degree of success. Stop by and strike up a conversation with them and see what they do. Hope some of this might help.

Eh? Oh, yes, I/we had a great time, thank you Deb! We played 12 rounds of (96 games) euchre and for me the cards were brutal....I won the consolation prize for the ladies :(. We all sang a great anthem though!!! Lol