Many of the plants in my garden have been showing signs of magnesium deficiency ranging from mild interveinal chlorosis to severe bleaching of the leaves with brown spots. (Each plant may show the signs a little differently, though interveinal chlorosis — leaves turning yellow while the veins remain green — is the predominant sign.) I knew I had to do something quickly!
My problem is interesting. Per all the soil tests I’ve had, my soil has sufficient magnesium. However, I have an incredible overabundance of calcium in my soil for some reason. And it’s that highly excessive calcium that makes it difficult for my plants to take up the magnesium from the soil. Thus, I have to supply the magnesium to my plants through their leaves (via a foliar spray) rather than through their roots (in the soil).
The easiest cure for magnesium deficiency is to apply epsom salt, which is magnesium sulfate. (For more information, see Epsom Salt in the Garden.) I normally apply it as a foliar spray of 1 tablespoon of epsom salt in one gallon of water, every two weeks. I hadn’t yet applied it to my spring plants this season, and my garden showed it.
So, I became garden doctor last weekend and made several batches of epsom salt foliar spray. Because of the severity of the symptoms, I doubled the epsom salt to 2 tablespoons/gallon of water and sprayed all the leaves heavily.
After one week, I can already see the improvement in my leaves. They’re still showing signs of deficiency, but it’s not quite as bad as it was. I will apply the double-strength epsom salt foliar spray again this weekend to be sure my plants are on their way to magnesium happiness, then I’ll go back to the regular dose (1 tablespoon/gallon of water) every two weeks.
Here are before and after pictures of some of my plants. The lighting in the before and after pictures is different, but you can still see some of the improvement in color.
The older radish leaves were very yellow, and the newer leaves weren’t as dark green as they should be. After a week, the yellow leaves are still yellow; but they’re not as bright yellow and the green in the veins is darker and thicker. The newer leaves are darker green, too.
My pumpkin leaves also show the classic interveinal chlorosis (as in the radish leaves, above). There isn’t as much difference in those leaves, but the newer leaves are darker than they were; so I know it’s starting to help.
Magnesium deficiency in corn is interesting. The leaves show thin, yellowish stripes. After a week, those stripes are less yellow and the leaves are darker green. (By the way, the leaves in the “before” picture are shiny because I took the picture after I had sprayed the leaves with epsom salt.)
The lower leaves of my beans were almost completely yellow and had brown spots on them. The top leaves were almost lime green. Yet, I think my beans are showing the most improvement after a week. Those top leaves went from light green to medium-dark green. (I didn’t take an official “before” picture, but I did take a closeup of one of the flowers that day, so you can still see the leaves before I applied the epsom salt.)
I had the same problem with the lima beans as I did with the snap beans, but not as many lower leaves were totally yellow with brown spots. The top leaves were quite lime green, though. Now the leaves are almost a forest green. Beautiful! Unfortunately, I didn’t take an official “before” picture the day I applied the magnesium. However, I do have a picture from two weeks ago that shows how the leaves are closer to a lime green than a forest green. (The “one week later” photo is showing the leaves one week after the epsom salt application.)
I’m sure I’ll see an even greater improvement in my leaves after this weekend’s application of epsom salt.
Do you have a magnesium deficiency in your garden? How are you curing it?