1) Every ingredient that you listed for the Fox Farm soil is extremely fine. Since water retention is dependant primarily on particle size, you should expect a medium made of all fine particulates to be extremely water retentive, something I try very hard to avoid in containers. 2) You can read about soils and how durable soils that remain well-aerated long after peat/compost-based soils have collapsed can offer a greater margin for grower error and make things much simpler for the grower if you follow this link. 3) Not necessarily, but if you think about it, what will you do if your pH falls outside the favorable range? Start adding acids and bases to change it? In commercial situations, pH is usually tested frequently and adjusted by injecting a wide variety of chemicals that have elements plants need into the irrigation water. Since pH is affected by temperature, fertility, plant material, moisture level, even time of day (Plants help to control the pH in the rhizosphere to make it easier for them to uptake nutrients. This effect is reduced when plants are undergoing periods of reduced transpiration, which in turn has an effect on pH.) I'm not saying that because I ignore trying to control pH that you should, but I've never found it necessary to fret about it in any container planting. I might consider the plant prefers acidic conditions and forgo the use of lime and maybe use a urea-based fertilizer to take advantage of the acid reaction, but other than that, I don't worry. Remember that Media pH is far less important in container media than in mineral soils, and if you're supplying nutrients in soluble form, unless the pH is WAY outside favorable limits, your plant will be able to assimilate the nutrients. You can find considerable discussion about this in Dr C Whitcomb's work, "Plant Production in Containers II". 4) On average, plants use about 6-10x more N than P. Since the P in NPK is not a true measure of P supplied (P is reportted as the % of P2O5 [phosphorous pentaoxide]) you need to use a multiplier of .43 to tell the actual amount of P. In 3:1:2 ratio fertilizers, there is 7x as much N as P, so you actually have a considerable cush in 3:1:2 ratio fertilizers. Plants use roughly the same amount of nutrients throughout the growth cycle in relation to N, so I'm not sure where the idea they need larger doses of P during flowering/fruiting comes from. Tissue analysis of fruits and blooms show roughly the same levels of P as other plant organs, which meshes nicely with the idea that consistent P levels at approximately 1/6 that of N are entirely adequate throughout the growth cycle. I actually don't boost K by adding the ProTeKt, I reduce the amount of N, which also must reduce the levels of P and K. Since I can see by my plants that what I said above about P is true (also confirmed in the text cited above, which is essentially the Bible on container production) and P levels remain adequate at reduced application rates of 3:1:2 ratio fertilizers, I only need to be sure plants are getting adequate K. I can do this by incorporating some potash in the soil when I make it in anticipation of the reduced N applications for tomatoes, or simply forgo the increase in TDC by supplying it later as needed by using the ProTeKt. Al

strawberry hill, your post is so interesting. I've never tested my soil but knowing that it's basically decomposed granite (in some places solid granite just 1 1/2 feet down) is a good clue. Growing the right roses for your area, as has been emphasized on this forum over and over, is in my opinion the most important lesson to learn. Having once chosen the right ones, there are still steps that can be taken, as you point out, to fine-tune the results. A lot depends on how much you can or are willing to do. I've found that coffee grounds from my husband's coffee consumption, alfalfa meal and adequate water are the simplest way for me to have good-looking roses. Judicious pruning also has its place. Poisons never will; I'd give up roses first. It's part art, part science and part the will of the roses to live and thrive. It's a little different for everyone, and it is endlessly fascinating. Ingrid

Call your local water provider and ask them what the pH is. They might have a web site with that information on it. Unless you get your water from a well, there is no reason to go to the expense of having it tested yourself.

Hello Lucas, Thank you for your input and questions :o) I will now try to answer some of them here : So let me ask by paraphrasing: you say that the only difference between Distilled ad RO-water is no ions at all compared to some ions, right? - Yes effectively this is the most important difference, since the reverse osmosis procedure is not 100% efficient, a lof more ions are left inside the water when compared to distillation. That in fact is more like basic - but is there a difference between RO- and distilled water in terms of susceptibility for drastic PH changes with the add of (as you call it) "a very very slight amount of acid"? And, what about other actual and pragmatical differences between RO-water and distilled water and their affinity for carbon dioxide out of the atmosphere? Is the difference notable, drastic or does it depend on how much and what kind of ions some specific RO-water still has? - Of course, as RO water has some ions it can have some added buffer ability. Depending on the nature of these ions the interaction with carbon dioxide might be very different. For example, if some carbonates are left within the water this will tend to creat a carbonate-bicarbonate buffer with time as carbon dioxide from the atmosphere is introduced. However some RO systems include ion-exchange columns that may in fact make the output water acidic. The final ionic composition of your RO water varies depending on the initial water source and the actual purification system. Let's say RO-water has between 15 and 50 ppm, just to have some workable figures handy. Is there a real difference with a highly purified (10-15 ppm) RO-water and distilled water in this context, and will a content of let's say 40-60 ppm of "impurities" change anything? - Yes, of course. distilled water has a conductivity that is for most practical purposes very close to 0 ppm. Just having and additional 1 ppm changes the buffer and pH responses of the water significantly. The more impurities you have, the lower the response will be to atmospheric carbon dioxide. However, this difference is not extremely important when using the water for hydroponics since the amount of salts is in either case small and the actual pH will be set by the hydroponic nutrients. What is the "final" conclusion, do you recommend RO-water for the use with nutrient solutions, either for commercial nutrients or for adequate "self-made" nutrients? - I would recommend RO water because distillation is a much more energy intensive process that yields water quality which is simply "unecessarily pure" for hydroponics. The additional 40-60 ppm of salts dissolved in RO water will most probably not make any noticeable difference while the process to obtain RO water is much less energy intensive. And finally, if using your recommended "Ion-exchange resin pH regulation" what would be the outcome if using them with RO-versus distilled water (without the add of any nutrients) - from a purely theoretical point of view of course, because it's not an actual practice nor procedure? Would there be ions to exchange at all with distilled water, when there are no ions...? I am not rhetorical with anything I am asking, - just interested in conclusion I can put into or transfer to actual practice. ;-) - The outcome with both wouldn't be very different after the solutions are prepared. Certainly if you use an ion exchange resin with RO water before preparing the solutions the water will be further purified to eliminate ions in exchange for acidic protons of the resin but in the end, after the addition of nutrients both RO and distilled water sources will have the same response. I hope this answers your questions :o) Thank you very much for your comment, Best Regards, Daniel