By August landscape gardeners may begin to notice certain woody plants….both evergreen and deciduous… have developed a yellow look. Yes, the foliage is decidedly not the green true to the plant’s healthier past. What’s going on?
Unless the plant is in death mood, by which one might already notice leaf drop, what is going on ….is, the plant is going chlorotic, meaning turning yellow due to chlorosis, the inability of the plant to take in certain nutrients. The soil has become less acid. The plant, one might say…or blog…is starving.
Plants typically affected are magnolias, azaleas, larch, Scot’s pine, white pine, oak…and many, many more acid soil loving plants. This disorder is more common on grounds with irrigation systems. Treated city water is alkaline. Over a long period of time artificial watering of ones garden can exacerbate the problem.
In addition some local soils are less acid than others. One does not have to run off to get a soil sample, only to know how to correct a local problem in the garden.
There are three soil acidifiers on the market, aluminum sulphate, ammonium sulphate, and garden sulphur. All are somewhat different remedies to the same problem.
Ammonium sulphate is a fertilizer as well as a soil acidifier. Ammonium tells us it provides nitrogen. It should not be used, therefore, if one does not want to add nitrogen to a plant’s soil environment, such as in August or September when, especially young plants, might be stimulated to delay hardening off, that is, acclimating for the coming harsh season. Landscape gardeners and others call that season, “winter”, and like our plant relatives sense it as our bleak season.
Aluminum sulphate is a granulated acidifier, usually added to a certain amount of water, and is made almost available “medicine” for the suffering plant to ingest. If you are growing sweet corn in your landscape garden…an interesting artistic maneuver, to be sure, chlorotic plants might show color improvement in a few days.
Garden sulphur, like aluminum sulphate, is not a fertilizer. Its effect to the soil environment is the same as aluminum sulphate, except it takes alot longer to be used by plants. Garden sulpher is to be sprinkled onto the soil around the suffering plants and worked into the soil. Water the area after application and then be patient.
August is a good time to cure chlorosis problems in your landscape garden. Mature plants may need many, many treatments.