Yellowing of rose leaves.

Some of my roses have yellowing of their leaves in between the green veins. Only some of them, and I managed to cure some of them a few months ago after using some Bonsai Food that somebody gave me, which had chelated minerals like EDTA chelated Iron and a lot of other chelated minerals in it.

I was wondering if there is any natural form of chelated iron, and was reading somewhere that grass clippings naturally chelate iron so you don’t need to keep buying expensive products containing chelated iron.

This is happening to roses grown in bought potting compost, so it isn’t to do with my garden soil’s pH.

If there is no natural form of chelated iron, what products do you recommend for chelated iron to get the best effect? The Bonsai Food was given to me by somebody who didn’t need it any more, and it contained more potassium than nitrogen or phosphorus and a lot of chelated minerals and humus and seaweed.

Hi Julie. I’m no expert, but if you have similar conditions to the ones I struggled with, maybe I can offer a couple of suggestions. As a groundskeeper in a college setting in [like you] zone 9 in the Los Angeles area, I looked after a planting of acid-loving plants. They were planted in a courtyard where the cement paving had been sprayed off with water to make a rough surface, with the cement slurry washed into the planting beds years before. Needless to say I struggled with chlorosis, yellowing between the veins, on some azaleas, camellias, gardenias, and general malaise in Australian tree ferns, even with nandinas. A product we used then [25 years ago] was called, I think, Acid-all, sold in 30 lb. bags that were bright yellow in color. It was a mixture of, I think, composted sewage sludge (like the famous Milorganite) and small pellets [prells?] of sulfur. It was very black and fertile-looking. I could apply it directly to the surface of the soil, allowing the sulfur to leach in over a couple of years, even with frequent irrigation. The Milorganite also gave the plantings a nice kick of nitrogen. Of course, it was effective mixed into the soil before planting. I get the feeling that sulfur pellets alone need to be used carefully, diluting their volume in the soil or else applied a season in advance. Anyway, this product really did the trick and was not especially pricy. I did a quick internet search before writing this and I didn’t immediately run across it. It may not be available anymore. There appear to be products that claim to do the same thing. You might look into products developed for the cannabis industry. Their exuberant graphics tend to make them stand out on the shelf. If you can get to a premium nursery in your area and can manage to find an associate with both experience and social skills [something of a challenge] you can maybe be directed to something effective.

Of course, yellowing between the veins can indicate several conditions. I found that our mineral soils in Los Angeles and San Diego counties had plenty of trace elements, but their availability to the plants was affected by soil PH. Getting that lowered solved all kinds of problems when trying to grow roses and other woodland plants for me. I hope it helps you too.

Thanks for this information. I am still searching online trying to decide, and I added some home-made compost to the soil of the roses that have yellowing leaves. I would have thought bought potting compost is coconut fibre, peat, or something similar, which should be acidic, but our tap water is alkaline, containing a lot of calcium, according to our water company our water is classified as hard, being pumped from underground sources in chalk.

I gather that Epsom Salt doesn’t change the pH of soil, even though it is Magnesium Sulphate and contains Sulphur, which I read gets converted into Sulphuric Acid by soil bacteria. Magnesium is an alkaline earth metal, like Calcium, so Magnesium Sulphate probably gives no net change. Though Magnesium itself is an essential part of the Chlorophyll molecule (and hence composted green garden waste should contain plenty of Magnesium?)

I am not sure what cement is made from, I will try to find out. It does sound as if it contains calcium which affected your particularly pH sensitive plants.

It sounds like your water might be the problem. You could use citric acid to acidify it prior to using it, if possible, or use rain water. There are pH testing strips that you can order on eBay…the more detailed the better from 4.0 to 9.0. It is fun to check your tap water’s pH and then add citric acid and check it again. Once the pH starts to go down (from let’s say 7.5 down to 6.0 or so) you know you’ve at least neutralized much of the alkalinity of the water…that is before the citric acid can lower the pH of the water it must first neutralize all of the calcium carbonate in there that really has the potential of raising the pH of the soil in your pots.

I am a male so my actual grasp of the science is likely much more tenuous than my confident tone implies.

I just bought and used a bit on my roses with yellowing leaves a product called Horticare Rose and Shrub Feed. I bought it from the Pound shop in the UK. I got it because it says it contains Iron, and also Manganese and Calcium, and it was extremely cheap, only one pound. It is dark brown and slightly smelly, I have no idea what is in it, other than it says it contains the usual Nitrogen, Phosphorus, and Potassium and Iron, Manganese and Calcium.

If it doesn’t do the trick of making the leaves turn green, I will have to get a more expensive product containing chelated Iron, or look for something like minutifolia recommends containing Sulphur.

Thanks, I will look for citric acid and pH testing strips. It could be our water, as the roses in pots are grown in bought potting compost not garden soil.

Cement is mostly calcium silicate plus a little calcium sulfate so that concrete is most likely the same except for sand and gravel (I looked up Portland cement on-line). Magnesium sulfate has the oxidized form of sulfur, sulfate, so if you take away the magnesium it is sulfuric acid. The final pH of the soil will depend on what kind of soil you add it to. Clay minerals are very complicated but are usually silicates with aluminum and some cations to balance the charge. They bind cations like Ca, Mg, Na, K, primarily. Too much sodium makes a clay that has dreadful properties for plants roots. Adding gypsum (calcium sulfate) allows the clay to aggregate so that it isn’t an impermeable mess. Magnesium helps. Potassium is an essential nutrient for plants so you don’t want the clay to get all of it, although plants are very efficient at extracting it from the soil.

The organic matter in a compost could be deficient in nitrogen if it is made from mostly straw=like material, or (peat)moss. IF you make it at home with lawn trimmings it is likely to be well balanced in everything essential, especially if the lawn is occasionally fertilized or has clover and other legumes growing in it. Organic matter in the soil chelates iron and trace elements in forms that plants can extract easily. that is one of its major functions in soils. Another is to react with the clay to reduce its stickiness and improve the air permeation. The third is to hold water in an easily extractable form for plants.

Hard water might be a bit alkaline, if it comes out of limestone, but the calcium and Mg are essential for good plant growth. Most likely there is enough iron around to start with, if there is some shale or other iron-containing minerals, but when the pH gets high, it turns to insoluble rust. That’s why it is chelated, to keep that from happening so fast. Before EDTA was invented, citric acid was used to keep the iron in the right form in hydroponic solutions. It is almost impossible to have too much iron in a soil. Some soils have as much as 20 % iron in them, and plants grow fine. It cannot hurt to add a lot of micronized iron, or chelated iron within reason.

Thank you, this is all very useful. Especially the big at the end about adding a lot of iron within reason cannot hurt. That helps when you are experimenting, and trying not to give the roses an overdose of fertilizer.