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Sunday, June 22, 2014

Why Do My Oleanders Have Yellow Leaves and Dropping?

Q. I also have questions regarding watering Oleanders (see attached pics). I have 2 separate hedges I'm currently grooming and both are in full sun exposure for about 6 hrs. My lawn currently waters them for 15 min. per day and they also each have 2 drip feeders at a rate of 2 gph each for 15 min. 3 times per day. The issue I'm having is the leaves are yellowing rapidly and appears to be worsening as the months go on. I did fertilize them this spring with 2 tbs of chelated iron to the soil and 1 tbs of liquid magnesium per bush. Did I over fertilize? I'm hoping this issue is not series as in leaf scorch.

A. Most of the problems on your oleander appear to be from the older growth and shading. I would prune them differently. I would remove one or two of the largest stems from the base of each plant, not prune at the top. You would do this next February, just before new growth. You will see new growth coming from the base and where the cuts are and in places where it receives light. Every year or every 2 or 3 years you will do the same to encourage new succulent growth from the base. Continually pruning at the top of the plants, hedging, will create big old wood at the base with no leaves. As the wood gets older, it drops its leaves. If you want to have leaves, you have to continually renew young growth from the bottom.

2 comments:

  1. I have never heard of fertilizing oleanders. That is adding more salt. Does it need it? In this case I am thinking temporarily yes. It would be interesting to dissolve small amounts of ammonium sulfate in water (read the application amounts on the bag, divide the amount by 12 and pour the resulting diluent around the root zone (but not the "trunk"). See if the leaves turn green in four days. If so nitrogen deficiency. If not, I'm wrong.

    ".... they also each have 2 drip feeders at a rate of 2 gph each for 15 min. 3 times per day...."

    1.5 gallons a day. In Phoenix the roots go down around six feet. I'd probably recommend targeting two feet watering depth. Depending upon how silty or sandy your soil is I would rather see an DEEP INFREQUENT watering schedule to put that salt in your water down deep and allow the roots to get adjacent soil drained.

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  2. If that is grass next to the oleanders I would move it back 18" from the trunks due to competitive and allelopathic effects of grass.

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