Some plants need applications of iron to our desert soils while others won’t need it. The type of iron fertilizer applied to the soil and when it is applied can be important in desert soils. EDDHA (ethylenediamine di-o-hydroxy-phenyl acetic acid) 6% iron chelate (marketed as 6% Iron EDDHA) holds iron in its grasp regardless of the soil pH or alkalinity. Not true of other iron chelates like EDTA, DTPA and others. The chelates they use are more sensitive to soil pH and begin to unravel and release their iron at a pH around 7.6. Most of our Las Vegas soils have a soil pH of about 7.8 to 8.2.

The reason iron chelates used as fertilizers, like the iron EDDHA chelate we carry, are only effective for about one more month. In other words, they soil applied iron chelates become less and less effective as it gets warmer. There are lots of technical reasons but remember that when soil applications no longer work, we have to shift to leaf or foliar applications (God forbid) of iron.

So get your iron applications on any time from late January to about May and then shift to leaf applied applications (foliar) when there is no more new growth. When trees like crape myrtle or roses yellow every year its best to just figure that will be part of their fertilizer regime here in the desert so apply it BEFORE you see the problem develop.

Viragrow sells soil applied EDDHA iron chelate in one pound and five pound containers as well as other forms of iron fertilizers.