No, it's not a gimmick. It's pretty effective at correcting iron deficiency in the short term. The content of the formulation isn't as important in terms of how well and fast it works as the form of iron. Some iron is a lot more soluble and available to the plants faster than others. Products like ironite (there are other brands, and generics as well) have chelated iron or other forms of iron that are rapidly taken up by the plant. Long run, you still need to correct the underlying imbalance in your soil chemistry. With your particular situation, part of it is just timing. Sulfur can take up to a year, from what I've read, to lower the soil pH, because it's not broken down very fast. You might want to use something faster acting, like aluminum sulphate, to get the pH down faster. But, the ironite will definitely help in the meantime. Be sure to mix per label and follow all directions, because this stuff can burn if you overdo it. Finally, there used to be a product on the market called S.T.E.M. (Soluble Trace Element Mixture) that was made by Sierra Grace, the people who made Peters brand fertilizers. I think Sierra Grace went belly up due to environmental lawsuits in the 1990's, but I think Peters brand name might have been taken over by someone else (Scott's Miracle Grow?). Anyway, I bought a big bag of S.T.E.M. many years ago, and it is good stuff. Alas, it's gone now, but it goes a long way. If it's still on the market, it would be a good thing for your blueberry. It contains all kinds of stuff, not just iron. One other thing I have heard of, but never tried, is to crush up a handful of multi-vitamin and mineral supplements with iron (like Flintstones with Iron, Geritol, Centrum with iron) and put those around the base of the plant. Probably couldn't hurt.

I found the link below. I quote in part ".... iron [that is] not water-soluble ... cannot be absorbed by plant roots. Such iron will be tied up indefinitely unless soil conditions change. This ... explains why rusty nails or iron shavings do not correct iron deficiency.... "Several methods are available for treating iron deficiency. These are: 1) soil application of elemental sulfur combined with ferrous (iron) sulfate; 2) soil application of iron chelates; 3) foliarsprays containing ferrous sulfate or chelated iron; or 4) trunk injection of ferric ammonium citrate or iron sulfate (trees only).... The link is to an extension.usu.edu file and has much more information and explainations. (The link is to .pdf file. If you don't want to bother with that you may google for "control of iron chlorosis" and get a link to display in HTTP.) Here is a link that might be useful: CONTROL OF IRON CHLOROSIS IN ORNAMENTAL AND CROP PLANTS

Over twenty elements are needed for a plant to grow. Carbon, hydrogen & oxygen are absorbed from the air & water while the rest are obtained from the nutrient solution. The rest of the nutrients & their source in nutrient solutions are: Primary nutrients: Primary nutrients are designated on the front label of fertilizers as the N-P-K ratio. Nitrogen Calcium nitrate Ca(NO3)2 Potassium nitrate KNO3 or Saltpetre Ammonium compounds (NH>sub>4) (see pH FAQ) Phosphate Potassium phosphate MonoPotassium phosphate KH2PO4 Potassium Potassium nitrate Secondary nutrients Secondary nutrients are used by plants in smaller amounts. Calcium Calcium nitrate [Ca(NO3) 2] Calcium chloride (CaCl2): May be used but adds extra chlorine. Some hydroponically grown plants are very sensitive to chlorine. Calcium Sulfate (CaSO42H2O): Can precipitate Magnesium Magnesium sulfate (Epsom salts) MgSO47H2O Trace elements (micronutrients) Trace elements are nutrients needed in small quantities. Boron Boric acid (H3BO3) Sodium borate (Borax) Chlorine Water Copper Cupric sulfate CuSO4 Copper chelate Copper sulfate CuSO4 5H2O Iron Iron ethylene-diaminetetraacetic acid (FeEDTA) Iron Diethylenetriaminepentaacetic acid (FeDPTA) Manganese Manganese sulfate MnSO4 4H2O Molybdum Ammonium molybdate (NH4)6Mo7O24 Sulfur (S) is taken up as sulfate (S04-) by plants Magnesium sulfate (Epsom salts) Potassium sulfate Zinc Zinc sulfate ZnSO4 7H2O Zinc EDTA Types of nutrient Hydroponic growers can mix their own fertilizer or purchase special hydroponic fertilizers. Hydroponic solutions need to be water soluble or their ingredients may precipitate. Nutrients that precipitate come out of solution, are not available for absorption by plants, & can result in deficiencies. Soil fertilizers are generally not advised since they are not water soluble. An example is N in the form of ammonia (NH4), and nitrate (NO3) discussed in the PH FAQ. Furthermore, soil fertilizers may not contain calcium & or all the trace elements since soil based plants take part of their nutrition from the soil. Hydroponic formulations are available in single or separate parts to avoid precipitation. Although there are some formulations that combine all the nutrients into a single mix most products separate them. Ions which can precipitate are kept apart until the final mixing. Generally, Ca is kept separate from the sulfate and phosphate salts. Hydroponic nutrients are available in grow & bloom formulas. Grow formulas promote vegetation & provide a higher N:K ratio. This means the first number on the front of the bottle (or the NPK ratio) is greater than the last. Bloom formulas will usually have more potassium (K) or a higher K:N ratio than the grow formula. This means the last number of the NPK on the bottle should be larger than the first. Bloom formulas promote budding, flowering, fruitset and vegetable production. They are used when budding starts & throughout the fruiting stage. Bloom is also good for plants that do not require nitrogen, such as cacti, succulents, & legumes. Different nutrients contain ingredients that have different purity & grades (pharmaceutical, pure, technical, food, or fertilizer) of its ingredients. This can affect the cost & solubility of the ingredients. Purity of the nutrient materials or chemicals is important in preparing a solution. Although fertilizer grades of chemicals may be used for some crops they have impurities. The higher grades of chemicals in the nutrient are less likely to result in impurities & precipitation. pH & nutrients See the pH FAQ. Mixing nutrient Nutrient, like acids require attention to safety in mixing. As discussed in the pH FAQ, mixing mineral salts can result in an exothermic reaction. These reactions can cause skin & eye injuries, & safety precautions (eyewear, protective clothing, etc.) are necessary. Manufacturer directions for mixing should be followed. In general, one should fill the container about ¾ full of water & slowly stir in the salt. When the particles disappear, add water & stir or let stand for several minutes to a day. It is important to wait until the particles are dissolved since they can clog pumps &/or cause deficiencies. Any material that comes into contact with the nutrient should be non reactive (stainless steel, glass, & non toxic plastic). Plant toxicity can occur when the nutrient is exposed to toxic metals or minerals. Nutrient interactions Nutrient interactions Plant deficiencies &/or toxicities may be due to nutrient interactions in solution. The terms "locked up, locked" out refers to when a nutrient is not available for the plant to absorb. Causes include pH (see the pH FAQ), displacement reactions, or precipitation reactions. Nutrients can be positive (cations) or negative (anions). An excess of cations is more likely to displace other cations. The name for this occurrence is a displacement reaction. For example, an excess of K+ can antagonize or impede the uptake the positive Fe, Mg, Mn, Zn. An excess of NH4+ can displace the positive (Mg, Ca, K, etc.). If the uptake of an element is impeded, it is not available for absorption & a nutrient deficiency may occur. Another way nutrient deficiencies can occur is nutrient precipitation reactions. Positive & negative nutrients can chemically bind & precipitate out of solution. For example, the negative sulfate (S04-) can precipitate with the positive Ca++ forming calcium sulfate. A material which has precipitated out of solution is not available for absorption & can result in a deficiency. Nutrient maintenance The following are tips on nutrient maintenance: Avoid using old nutrient since precipitation reactions can occur. With closed systems, the nutrient is placed below the grow tray so it can recirculate back into it. 2 Topping off nutrient should not include full strength nutrient since concentrated nutrient can chemically burn the roots. Furthermore, mkirkwag recommends: "When I bought my first nutrients, they laid out an amount per gallon for a new fill, and a lesser amount for top-offs. Each successive top-off got less nutrient per gallon, and of course, when the water is changed out, you start over again with the full strength. "1 Flow rates The following is a general guide for flow rates. Higher rates may be needed depending on the crop grown or during the summer due to evaporation. Open systems may need nutrient four times daily or more depending on the plant. Plants are normally supplied nutrient four to six times during daylight hours. Drip system: Flow rates of 1 drip/second. With NFT, plants may be given nutrient around the clock, which can result in greater nutrient uptake. Ebb and flow: The pump should remain on for about 15 - 30 minutes, which is called a flood cycle. This should be done 4-8 times daily depending on the plant size, evaporation rates, & the media used. The entire flood & drain cycle should not be more than ½ hour or root damage can occur. Aeroponics has a misting cycle which is generally 2 minutes on & 5 minutes off 24 hours daily. When to change nutrient: Nutrient is changed each time with open systems, whereas with closed systems nutrient is changed biweekly. A system with a small reservoir may need nutrient changed more often than a system with a large reservoir. A system with many plants, large plants, or heavy nutrient users may use up nutrient at a faster rate & need to be changed more often. If plants exhibit deficiency symptoms nutrient should be changed. The system may need to be flushed depending on which deficiency is suspect. NUTRIENT DISORDERS Deficiencies Deficiencies can occur because of dilute nutrient, nutrient reactions in solution, or pathogens. Symptoms of toxicity & deficiency may be similar. Growers should routinely assess their plants, paying close attention to symptoms on leafs, roots, stems, etc. Leaf tissue is the main area where nutrient symptoms appear. Although leaf analysis is the best indicator of plant nutrition it is expensive. Observing whether the symptoms started first on the older or younger leaves limits the cause to mobile versus immobile nutrients. Mobile nutrients (P, Mg, & Cl) can move from where they are stored to places where they are needed. Deficiency symptoms appear mostly in the lower (older) leaves. Symptoms occur because the nutrient has moved to the younger parts of the plants; thus leaving older leaves deficit. N forms are also mobile - & the NO3- ion is more mobile than NH4+. Immobile nutrients (Ca, B, & Fe) produce symptoms in the younger leaves. K, Zn, Cu, Mn, S, & Mo are intermediate in plant mobility & under certain circumstances the intermediate elements are mobile. Which nutrients are mobile, immobile, & intermediate vary, however, depending on the source. Adding micronutrients to treat a deficiency causes problems since nutrients can antagonize each other resulting in an excess of deficit of other nutrients. General recommendations for treatment include the following: Avoid overcompensation - it can result in nutrient excess &/or other disorders. Change the nutrient weekly instead of biweekly. Switch to a different hydroponic fertilizer. Apply a salt that contains only the deficient micronutrient. A micronutrient complex is not used since it can cause antagonism. Micronutrients can be added over time in small amounts with the irrigation water, applied once with a concentrated solution with water, or applied as a single foliar spray. When applying foliar sprays, apply daily or every other day during cool temperatures. A wetting agent prevents water from beading up & burning the leaves. Toxicity Toxicities more difficult to correct than deficiencies. The first step is to stop adding the micronutrient that is in excess. General recommendations for treating toxicities are: Switch to a fertilizer without the toxic nutrient. Some nutrients can be lowered by raising the pH. Use antagonism methods - slightly increase the level of a micronutrient that will reduce the availability of another (e.g., if Zn is at high levels, slightly increase the Cu). 1 mkirkwag 2leafbrain2003a

Moved info. from another thread as to pH preference of different roses: Take YOUNG own-roots in a nursery setting, watered with alkaline tap water (pH over 7.5). Young own-roots are wimpy, haven't secret acid yet, thus need an acidic medium like pine fines (pH 4) or peat (pH 4) & perlite to make minerals soluble in water to feed their tiny roots. Folks who grow roses in cold zone get tons of acidic rain plus snow, and need to lime roses per many inches of rain, if that rose is grafted on aggressive root-stock that secret acid. Dr. Huey-rootstock can go through rock-hard clay better than my shovel through its ability to secret acid. The pH requirement of roses change .. when they are young own-roots are like alfalfa sprouts, they can't secret acid, thus need an acidic medium. But as they get older and roots become more solid and woody, such as 3rd year on, that solid wood secrets plenty of acid. I bought an organic, very acidic SOLUBLE fertilizer, got some on my skin and it burned. I used the dose as recommended, it has acidic soy bean, kelp, and sulfate of potash .. my galllon-size own root roses love it !! Leaves became dark-green, but that acidic solution fried the leaves of 4th-year own-root Sweet Promise (with shiny & glossy and dark-green foliage). Roses grafted on multiflora rootstock, or have multiflora parentage dislike alkaline soil (become pale), thus these roses need an acidic soil to have darker leaves. In contrast, roses grafted on Dr. Huey, or have French Meilland or China parentage are healthier with higher pH. Old Garden roses were bred in the Old days, without high-pH tap water & only acidic rain at pH 5.6, thus prefer acidic soil. Modern roses are bred with alkaline-tap-water, and the most vigorous and dark-green tend to prefer such medium that they were bred, with pH over 7.5 like alkaline tap water. Intrigue hybrid tea is an example, 100% healthy in a pot, grafted on Dr. Huey, tons of buds, with alkaline tap-water pH near 9 (baking soda pH is 8.3). That was for $5 at Walmart. I didn't buy it, since I already saw Intrigue in spring time at the rose park with tons of acidic rain: it was a blackspot fest, and stingy too. But in hot & dry summer, Intrigue bloomed great with alkaline tap water at the rose park. Intrigue has dark-green leaves. Same with Perfume Delight, BS-fest with acidic rain, also dark-green leaves. To have dark-green leaves, roots must secret enough acid to get iron and manganese for dark-color .. such dark-green leaves roses secret more acid to utilize the minerals to make their leaves deep green. As the pH drops, less calcium and potassium are available, thus leaves are more susceptible to fungal diseases unless alkaline minerals is given.