A teaspoon in a gallon of water would be enough to see if the plant responds to either a magnesium deficiency or that the soil has too much phosphate. It is very soluble.

Thanks much Ted. Leads to a 2nd question of course.

The context of last years post was about a/my non-flowering dahlia.

Is the use of ES just for that reason - to test the soil for less than stellar performance or for problem dahlias? Or is this general advice for use on any and all container dahlias? (Unless I'm the only one out there NOT using ES, I suspect many others might be interested as well.)

Thanks in advance

P.S. I ask because this year I have a WONDERFUL crop (about 28 so far) coming up. A couple will even bloom in the next few weeks. (Last year I had maybe 10 coming up by June 1 and some that are already up this year NEVER came up last year) I want to keep them as happy as they seem to be now.

Is the use of Epsom Salts just for that reason - to test the soil for less than stellar performance or for problem dahlias? Or is this general advice for use on any and all container dahlias? (Unless I'm the only one out there NOT using ES, I suspect many others might be interested as well.)

Epsom Salts has been call a "folk remedy" for gardeners for over a hundred years. One scientist at WSU believes that ES is effective only on plants that have a magnesium deficiency. My soil was tested and was deficient in Magnesium. In hanging pots, the use of liquid fertilizers can create excess salts and phosphorus in the planting mix and a decline in growth. Greenhouse plant growers use ES to "revive" the plants. I believe in this case the magnesium ties up the excess phosphorus and allows the plants to use nitrogen and iron to produce green leaves. It worked for my hanging pots last year. I had tried additional iron, additional nitrogen and the plants did not respond. When I used ES they turned green again and put on lots of new growth.