Iron is only a micronutrient and the average garden soil contains about 3 pounds of the stuff per cubic foot. The problem is that plants only take up iron compounds which are water soluble and only in the less stable ferrous, rather than ferric, form. All sorts of soil conditions can convert ferrous iron into less soluble and therefore less plant-available iron compounds. Iron chelates are compounds of ferrous iron which are water soluble and resist conversion to less soluble compounds. Any compound which is water soluble cannot persist in the soil - water will wash it out. If the soil conditions which lead to iron deficiency persist throuhout the year, probably the longest lasting approach is to try lowering the soil pH with sulfur. If you choose to use an iron chelate, you might have to apply it every two weeks or so, just as you would a water-soluble source of nitrogen such as MiracleGro.

. . . so that Rose Tone and chelated iron can in fact be considered independent of each other. However, the earlier version of Rose Tone (~5 years ago) contained ammonium sulfate. This particular form of nitrogen fertilizer acidifies moderately and can improve the uptake of iron.

Thanks. This looks like the "Mike only" thread, lol.
I guess I could have mentioned, too, that all my roses are in pots, in potting soil rather than garden soil. Perhaps that has something to do with the lack of iron?
Mike R, so if pH effects the iron uptake, wouldn't regular applications of organic matter help keep the soil pH down somewhat?
Every couple weeks? OK. That will solve the question of what to do with this 5lb bag I bought that I though would last the rest of my life. : )
Mike

Since this is the "Mike" only thread, I'll ask you how long these have been in the pots, and have you changed the potting mix the last few years?

Most organic matter can be regarded as pH neutral. Peat acidifies. Some mushroom compost is full of lime and strongly alkaline. mike_rivers thinks organic matter tends to raise pH in the very long run.

The roses are various ages. The ones planted just this spring looked fine before the chelated iron. But even ones I planted just last year were looking pale. I try to repot, remix with significant amounts of new soil, at least every 3 years. I can't swear that none of them go longer. But it was virtually all the roses that looked depleted.

Is there a form of slow release soluble iron?

Having the same problem.

Veronica (not Mike)

The long-term fix is to lower pH with sulfur (after checking the pH) and prevent waterlogging, which also induces iron deficiency.

You could also fertilize regularly with Miracid, which doesn't actually acidfy significantly, but contains a good amount of chelated iron.

I haven't seen a study of comparative effectiveness, but Lily Miller IronSafe is supposed to be somewhat slow release.

Veronica, Osmocote Plus is a polymer-coated slow-release fertilizer. The label states that it's good for 6 months and that it contains, among a variety of other nutrients, coated, slow-release iron.

A "synthetic chelate" made by mixing a cup of ferrous sulfate with 1 bushel of compost is often recommended to treat iron deficiency. I've used a mix of alfalfa pellets and peat in place of the compost and the stuff appeared to work very well (I didn't have any control to compare it with). There have been several recent scientific papers on compost/iron mixtures and their effect is attributed to natural iron chelates produced by microorganisms in the compost.

Thanks, Mikes,

Very helpful. I have miracid on hand and Ferrous sulfate is on the shopping list.

Pearl D"or and Blumenschmidt seems to always need iron here.