How often should I add acid around my magnolia in my North Texas alkaline soil, and what is best? Ironaid or that ferro-whatever stuff? I've been putting a cup of ironaid in wedged-out holes around the dripline every few years, and it's ok but not great--should I powerspay directly onto the foliage, and if so when how much and how and so forth?
magnolias in alkaline soil
I'm assuming that you are speaking of Magnolia grandiflora. How large is the tree? How long have you had it? M. grandifloras have roots that extend well, well, well beyond the drip line. As the tree gets bigger, it will get even more difficult to maintain in good health, as you have probably already discovered. If the tree is still small, you may want to cut your losses and replace it with a magnolia that grows in alkaline soil. I'd stick with the dry applications , but extend the applications well beyond the drip line. The problem with a foliar spray on magnolias is that the leaves are so leathery and slick that the spray will bead off unless you use a surfactant. I've never used a surfactant on something I want to keep healthy. I don't know what a surfactant would do to the leaves of an "ok" tree. Every thing I have read about situations like this indicate that you are just prolonging the inevitable. Trees under stress are more likely to fall prey to diseases.
www.edis.ifas.ufl.edu/ST371
www.whiteoaknursery.biz/essays/trees_alk_soils.pdf
We have extremely alkaline soil and there are two neighbors that have huge Magnolias that are now 40 years or more. They don't add anything other than whatever fertilizer goes on the lawn twice a year. The trees are very healthy. No problems whatever.....they are always covered with blooms. Could be that when these were planted.....they lucked out and got the ones Betty refers to. (I know don't end a sentence with a preposition) Our homes were new then and built smack dab in the middle of a former hay field.....nothing but Johnson Grass. Only thing anyone could do then was with elbow grease.....no chemicals for anything...good or bad.
LouC, it's ok now to end a sentence a preposition with (maybe not so much like this)
Bettydee, you were right about the gardenias, so I believe you. The tree's too big to cut down so I'll put my apps farther out.