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How to Treat Blueberries with Yellowing Leaves

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.

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.

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 you're 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 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.

14 comments

  • Lily, you probably do not need to do anything until spring. But once you start to see new growth in the spring and the leaves still look yellow, you will want to check the pH of your soil If it is too high then your plants cannot take up the iron in the soil. If the pH is in the range the plant likes, then you can feed with some iron.

    Suzanne
  • My blueberry tree has all of the leaves yellow. What does that mean and what should I do? Thank you so much! Lily

    Lily
  • JB, blueberry leaves will turn colors in the winter and depending on where you live, might drop all their leaves over the winter. In the spring you can give them a feeding of acid loving plant fertilizer. You really should not fertilize this time of year. The plants are getting ready to go dormant.

    Suzanne
  • My leaves are yellow and red. It appears the plant is dying. How do I save it ?

    JB
  • Helen, I do not think treating in September is too late. Make sure your pH is correct as well as adding iron.

    Suzanne
  • We live in the bluegrass of Kentucky and my pink blueberry plant needs iron (soil test from extension center). It is mid-September, is it too late to apply the iron treatment?

    Helen Curtis
  • What is the treatment for wet spring? Just let them dry out a little? Here in Southern CA we’ve had very hot days followed by temperate, so it’s been tricky to get the watering just right. Might also invest in a soil moisture meter to help with this!

    Kweez
  • Two of my blueberry bushes have yellowing leaves with black spots on them. What does that mean and what should I do? Thank you so much! Teresa

    Teresa
  • Teresa, sounds like you might have Septoria leaf spot. You can treat it with a fungicide labeled for Septoria. Do not overhead water your plants and increasing the spacing between plants will help with increasing air circulation.

    Suzanne at GrowOrganic.com
  • Teresa, sounds like you might have Septoria leaf spot. You can treat it with a fungicide labeled for Septoria. Do not overhead water your plants and increasing the spacing between plants will help with increasing air circulation.

    Suzanne at GrowOrganic.com
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