Xtremehorticulture

Oleanders Drop Leaves in Drought. Will it Recover?

Q. I read the post on your blog on oleanders with
interest. I too have an issue. My five oleanders are mature (at least 20 years
old) trees.  When we moved here a year
ago they had not been watered.   When the
water was turned on and major landscaping installed, many of the leaves turned
yellow and dropped. However the trees blossomed and continued to do fine. 
This is not the readers oleander but this oleander has leaf
scorch and leaf drop while the oleander behind it is
doing very well. Check the emitters or the source of water.
This is a good sign it is getting a lack of water.

            During
the rains the gardener turned off the water system and sadly forgot to turn it back
on. The water is of course back on but I have had to replace many bushes, although
NOT the oleanders.  However they have
begun to turn yellow again and are dropping leaves. There are still a majority
of green leaves and the trees are about to burst into blooms. They have been
fertilized, as has everything on the property, but I am baffled.  Would you be so kind as to give me your
advice on what is happening and why?

A. Oleanders are so extensive worldwide that no one is
sure where they originated from. Their climate of origin is important because
it determines under what conditions these plants perform best but we do know
quite a bit about how oleanders behave with and without water.
            We know
that they are very drought tolerant. This means that when there is limited
water, they can survive. Many plants can’t do this. Normally when drought
tolerant plants first experience a lack of water the leaves will drop and the
canopy will become sparse. If the water continues to be sparse the leaves they
produce will be few and smaller and little new growth. They have to have a
sparse canopy to survive.
            However
when water is present they have the potential for using a large amount of water
and are not low water users. They respond to this water by growing more,
setting new leaves that are quite a bit larger and shedding the old ones. The
plant itself becomes denser and flowers profusely (provided they are not
trimmed with a hedge shears).
            Leaf
drop is very characteristic in response to a drought. It is also characteristic
when they receive water again after a drought. It is also characteristic of
older growth to shed some leaves on older wood.
            So, in a
nutshell, going from drought to abundant water expect some leaf drop. And when
oleander grows normally, expect some leaf drop as the plant matures but not
typically as much as during dry/wet periods. So is oleander a good pool plant?
No.

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