How to Treat Blueberries with Yellowing Leaves

Blueberry yellow leaves

What is causing those yellow leaves with dark green veins?

Blueberries are a wonderful fruit, tasty, healthy and the bushes make attractive landscape shrubs. They are easy to grow once you get the soil and water right, but if they have a problem they let you know! Some of my blueberries have begun to exhibit classic signs of iron chlorosis, that is iron deficiency. A blueberry with iron deficiency has yellowing leaves with dark green veins, the new growth will be affected by this first.

Iron deficiency in blueberry plants

Now, before you run off and bury iron nails next to your blueberry bushes one of the biggest culprits of this problem isn't that the soil doesn't have enough iron, but that the plants can't use the iron in the soil. Blueberries are unable to use the iron in soil when the soil pH is too high. Blueberries like their soil pH to be between 5.2 and 4.0 with the optimum being 4.5 to 4.8. Another problem that can cause iron chlorosis is too much water, this can happen with wet springs or irrigation that is set to water amounts that appropriate for the summer heat but not a cool spring.

How to test for iron deficiency in the soil

The first step to address this problem is to do a pH test. This simple, inexpensive pH test kit is perfect for this type of monitoring. You'll need to prepare a soil sample and the kit contains instructions, you can also watch a video of Tricia showing you how to prepare a soil sample. Once your sample is taken, dried, and crushed put a cap and a half full in in the test tube and 4ml of reagent, shake for 30 seconds and you're in business. Looks like a pH of 5.0

This is the soil test for my Reka blueberry which seems to be the most unhappy of my five bushes. It looks like the pH is about a 5.0 which is ok for blueberries, looks like my problem might be a bit of a wet spring!

Elemental Sulfur and a pH Test

How to cure the blueberry plant

If your test comes out with a high pH you can add iron sulfate or elemental sulfur in the recommended amounts. Other helps to lower the pH is a pine needle mulch and the addition of peat moss. You can also fertilize your blueberries with an acidic fertilizer like Cottonseed Meal or Acid Mix. If your blueberries are going into containers, a mix of half potting soil and half Peat Moss works well.

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20 comments

Rose, if your pH is in the correct range and you are still having issues with symptoms of iron deficiency, you should add an iron supplement. Ammonium sulfate is not an organic source of nitrogen.

Suzanne

Some of my blueberries have yellow leaves. I know is some deficiency of iron cause the ph if in between 4-5. Can I added a nitrogen like ammonium sulfate even am trying to grow it organic

Rose

Rose, clay soil can be acidic but the 50/50 mix will probably fine. I would test your pH after you make the mix to see where you are at with pH.

Suzanne

Eric, are the plants all getting the same amount of water and is the pH pretty consistent throughout the bed? What is your pH of your soil? You might try fertilizing with some acid-loving fertilizer, give it little iron and some trace minerals.

Suzanne

I have blueberries in containers but I want planted in the ground my soil is clay with 7.5 is above neutral can I mix canadian peat moss at rate of 50% and the other 50 of native soil which is clay

Rose

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