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.
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.
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.
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.
Did any of the watering changes keep the leaves from turning yellow and dropping? I am having same problem with my oleander trees – leaves are yellowing and dropping…
Usually I like to apply the KISS principle first and in the desert that usually means water. Many people think that oleander, because it survives some of the toughest environments in the desert, is low in its water use. Yes, it is drought tolerant but not low in its water use. I.e. it can survive without a lot of water but it dies back and drops its leaves when it's threatened like this. Leaf drop/yellowing is often times the first warning that a plant is either not watered enough, watered too often or planted to deep if it's recently planted. The KISS principle tells me to eliminate the water issue first since it's the simplest to do. Take a hose and watered the heck out of them once a week and see what happens over the next two weeks. Eliminate the other two possible issues; watering too often and planted too deep. If it's recently planted, make sure it was planted so that the stems are not covered in soil and kept wet. Don't water these plants every day. They don't need it and don't like it. Water it like you would any other tree or shrub that has deep roots.
Thank you – We upped the water time and are watering it twice a week Mondays and Fridays and will see what happens. Do you know anything about canary palms? I can send a photo –
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