Hello Steve,

Epsom salt only supplies certain nutrients (magnesium and sulfur, as per info on the linked page) and should only be used when a laboratory soil test reveals deficiencies in those particular nutrients. (Home test kits do not screen the soil as thoroughly for as many nutrients, and pH results can also be hard to read accurately compared to lab results.) Its only benefits are like those of any fertilizer -- supplementing nutrient levels if they are low in the soil. Fertilization with any nutrients not deficient in the soil has limited benefits as the roots already have access to all they need, and runoff from applications can pollute stormwater.

Limestone alters soil acidity (pH), and in that way is a chemical, and is only needed periodically if that same type of lab test shows that the soil pH is too low (acidic). Labs tend to include recommendations for lime application amount per area of ground if measured pH is outside of the range of the "crop" (basic categories like lawn, vegetables, acid-loving shrubs, etc.). We would doubt that most soils would need a yearly application to correct pH; that sounds too often, unless a pH were very low at the start of cultivating that area.

Watering frequency/regularity is the main factor behind blossom end rot vulnerability, other than perhaps certain cultivar susceptibilities to developing that kind of disorder. While calcium (like that in limestone) can help prevent it, it's not often due to a calcium deficiency, just that uptake through water absorption in the root zone is insufficient for the plant's needs. (Plants consume nutrients dissolved in water that roots absorb; they can't absorb it "dry," so underwatered plants can develop nutrient deficiencies, at least temporarily.) Soil acidity can influence blossom end rot as well if it's too low for calcium to be unbound from the soil and available to roots.

Miracle-Gro has many formulations and they can vary in their suitability for vegetables, though honestly, most complete fertilizers (those providing all the major nutrients) should suffice interchangeably most of the time. Our Fertilizing Vegetables and Garden Fertilizer Basics pages may be helpful when determining what nutrients to look for in a fertilizer. Generally, liquid-type fertilizers are fast-release, being absorbed more readily but not lasting as long (and potentially also leaching out of the soil faster as well) compared to granular/pelleted types which are slow-release or time-release, which break down more slowly but last longer overall.

Miri

Thanks for your reply.

Iron sulfate can be a fertilizer ingredient used to both supplement iron levels and acidify the soil. Vegetables usually don't need soil acidification unless a soil test has shown that the pH level is well above neutral, and unless a soil test also shows iron is lacking, supplementation is generally not needed. (Too much iron can damage plants, so it's not recommended to add any without iron-deficiency plant symptoms or very low soil levels.)

Miri