Need a better way to prune the tops of a thick oleander bush

[Danny D]

Trimming question ...

I made a mistake buying the Echo HC-150 20-inch hedge trimmer:
Loading Image...

The trimmer is (way) too small to make the tops flat of my
Oleander bush.

I can't get the 20-inch blade across the top, while standing on
a step ladder, from the one side. The problem is that the other
side is wholly inaccessible to a ladder, so I can only trim the
top of the bush from one side.
Loading Image...

The Oleander bush is something like five or six feet across,
and something like nine or ten feet tall, for something like
a few hundred feet along a cliff-like extremely steep hill.

I can easily climb up on a step ladder to cut the side, but,
I can only lean over about three or four feet across the top
with the puny 20-inch 21.2cc hedge trimmer - and even that is
risky because one fall could be dangerous with a hedge trimmer
(I've already sliced my thigh with the thing in the past).

So, I'm mostly asking if there are better ideas for how to
cut the top of a tall and thick Oleander bush when you can only
access it from one side, and when your trimmer is 20 inches
while the bush width is at least three times that.
Loading Image...

Any helpful suggestions?

[Oren]

Post by Danny D
Trimming question ...
http://www2.picturepush.com/photo/a/12891035/img/12891035.jpg
The trimmer is (way) too small to make the tops flat of my
Oleander bush.
I can't get the 20-inch blade across the top, while standing on
a step ladder, from the one side. The problem is that the other
side is wholly inaccessible to a ladder, so I can only trim the
top of the bush from one side.
http://www1.picturepush.com/photo/a/12891079/img/12891079.jpg
The Oleander bush is something like five or six feet across,
and something like nine or ten feet tall, for something like
a few hundred feet along a cliff-like extremely steep hill.
I can easily climb up on a step ladder to cut the side, but,
I can only lean over about three or four feet across the top
with the puny 20-inch 21.2cc hedge trimmer - and even that is
risky because one fall could be dangerous with a hedge trimmer
(I've already sliced my thigh with the thing in the past).
So, I'm mostly asking if there are better ideas for how to
cut the top of a tall and thick Oleander bush when you can only
access it from one side, and when your trimmer is 20 inches
while the bush width is at least three times that.
http://www2.picturepush.com/photo/a/12891105/img/12891105.jpg
Any helpful suggestions?

- garden pruning sheers

- pruning loppers

- machete

- 4X4 truck w/ nylon strap

[ChairMan]

Post by Oren

Post by Danny D
Trimming question ...
http://www2.picturepush.com/photo/a/12891035/img/12891035.jpg
The trimmer is (way) too small to make the tops flat of my
Oleander bush.
I can't get the 20-inch blade across the top, while standing on
a step ladder, from the one side. The problem is that the other
side is wholly inaccessible to a ladder, so I can only trim the
top of the bush from one side.
http://www1.picturepush.com/photo/a/12891079/img/12891079.jpg
The Oleander bush is something like five or six feet across,
and something like nine or ten feet tall, for something like
a few hundred feet along a cliff-like extremely steep hill.
I can easily climb up on a step ladder to cut the side, but,
I can only lean over about three or four feet across the top
with the puny 20-inch 21.2cc hedge trimmer - and even that is
risky because one fall could be dangerous with a hedge trimmer
(I've already sliced my thigh with the thing in the past).
So, I'm mostly asking if there are better ideas for how to
cut the top of a tall and thick Oleander bush when you can only
access it from one side, and when your trimmer is 20 inches
while the bush width is at least three times that.
http://www2.picturepush.com/photo/a/12891105/img/12891105.jpg
Any helpful suggestions?

- garden pruning sheers
- pruning loppers
- machete
- 4X4 truck w/ nylon strap

fergot one..

-mexicans<g>

[Oren]

Post by ChairMan

Post by Oren

Post by Danny D
Trimming question ...
http://www2.picturepush.com/photo/a/12891035/img/12891035.jpg
The trimmer is (way) too small to make the tops flat of my
Oleander bush.
I can't get the 20-inch blade across the top, while standing on
a step ladder, from the one side. The problem is that the other
side is wholly inaccessible to a ladder, so I can only trim the
top of the bush from one side.
http://www1.picturepush.com/photo/a/12891079/img/12891079.jpg
The Oleander bush is something like five or six feet across,
and something like nine or ten feet tall, for something like
a few hundred feet along a cliff-like extremely steep hill.
I can easily climb up on a step ladder to cut the side, but,
I can only lean over about three or four feet across the top
with the puny 20-inch 21.2cc hedge trimmer - and even that is
risky because one fall could be dangerous with a hedge trimmer
(I've already sliced my thigh with the thing in the past).
So, I'm mostly asking if there are better ideas for how to
cut the top of a tall and thick Oleander bush when you can only
access it from one side, and when your trimmer is 20 inches
while the bush width is at least three times that.
http://www2.picturepush.com/photo/a/12891105/img/12891105.jpg
Any helpful suggestions?

- garden pruning sheers
- pruning loppers
- machete
- 4X4 truck w/ nylon strap

fergot one..
-mexicans<g>

a.k.a. "mexican" drag line and backhoe = shovel

[Robert Macy]

Post by Danny D
Trimming question ...
 http://www2.picturepush.com/photo/a/12891035/img/12891035.jpg
The trimmer is (way) too small to make the tops flat of my
Oleander bush.
I can't get the 20-inch blade across the top, while standing on
a step ladder, from the one side. The problem is that the other
side is wholly inaccessible to a ladder, so I can only trim the
top of the bush from one side.
 http://www1.picturepush.com/photo/a/12891079/img/12891079.jpg
The Oleander bush is something like five or six feet across,
and something like nine or ten feet tall, for something like
a few hundred feet along a cliff-like extremely steep hill.
I can easily climb up on a step ladder to cut the side, but,
I can only lean over about three or four feet across the top
with the puny 20-inch 21.2cc hedge trimmer - and even that is
risky because one fall could be dangerous with a hedge trimmer
(I've already sliced my thigh with the thing in the past).
So, I'm mostly asking if there are better ideas for how to
cut the top of a tall and thick Oleander bush when you can only
access it from one side, and when your trimmer is 20 inches
while the bush width is at least three times that.
 http://www2.picturepush.com/photo/a/12891105/img/12891105.jpg
Any helpful suggestions?

Following the philosophy of 'using what you have' I used a set of nail
nippers. They go straight down to the cut, are fairly strong, BUT only
one branch at a time. At least you only have to do the 'husky'
trimming once. After that the puny trimmer should work. right?

[David Hare-Scott]

Post by Danny D
Trimming question ...
http://www2.picturepush.com/photo/a/12891035/img/12891035.jpg
The trimmer is (way) too small to make the tops flat of my
Oleander bush.
I can't get the 20-inch blade across the top, while standing on
a step ladder, from the one side. The problem is that the other
side is wholly inaccessible to a ladder, so I can only trim the
top of the bush from one side.
http://www1.picturepush.com/photo/a/12891079/img/12891079.jpg
The Oleander bush is something like five or six feet across,
and something like nine or ten feet tall, for something like
a few hundred feet along a cliff-like extremely steep hill.
I can easily climb up on a step ladder to cut the side, but,
I can only lean over about three or four feet across the top
with the puny 20-inch 21.2cc hedge trimmer - and even that is
risky because one fall could be dangerous with a hedge trimmer
(I've already sliced my thigh with the thing in the past).
So, I'm mostly asking if there are better ideas for how to
cut the top of a tall and thick Oleander bush when you can only
access it from one side, and when your trimmer is 20 inches
while the bush width is at least three times that.
http://www2.picturepush.com/photo/a/12891105/img/12891105.jpg
Any helpful suggestions?

Long handled loppers are made with telescopic stems about 3 m long. They
can cut quite thick branches if it is green and soft.

David

[David E. Ross]

Post by Danny D
Trimming question ...
http://www2.picturepush.com/photo/a/12891035/img/12891035.jpg
The trimmer is (way) too small to make the tops flat of my
Oleander bush.
I can't get the 20-inch blade across the top, while standing on
a step ladder, from the one side. The problem is that the other
side is wholly inaccessible to a ladder, so I can only trim the
top of the bush from one side.
http://www1.picturepush.com/photo/a/12891079/img/12891079.jpg
The Oleander bush is something like five or six feet across,
and something like nine or ten feet tall, for something like
a few hundred feet along a cliff-like extremely steep hill.
I can easily climb up on a step ladder to cut the side, but,
I can only lean over about three or four feet across the top
with the puny 20-inch 21.2cc hedge trimmer - and even that is
risky because one fall could be dangerous with a hedge trimmer
(I've already sliced my thigh with the thing in the past).
So, I'm mostly asking if there are better ideas for how to
cut the top of a tall and thick Oleander bush when you can only
access it from one side, and when your trimmer is 20 inches
while the bush width is at least three times that.
http://www2.picturepush.com/photo/a/12891105/img/12891105.jpg
Any helpful suggestions?

Oleander is really not suited for trimming as a formal hedge with a flat
top and flat sides. It grows too fast. You would need to trim it
monthly.

If you think the hedge is overgrown, use a pruning saw to cut each plant
down to about 20 inches from the ground. Within a few months, it will
again be a hedge.

However, if you are in southern California, forget it. Oleanders are
dying from a blight for which there is no cure. See
<http://www.ipm.ucdavis.edu/PMG/PESTNOTES/pn7480.html>.

[Danny D]

Post by David E. Ross
If you think the hedge is overgrown, use a pruning saw to cut each plant
down to about 20 inches from the ground. Within a few months, it will
again be a hedge.

My wife loves the white flowers but it's crowding the driveway so I
have to lop off a foot or more to trim it back on the sides.

On the top, I just want it to look neat'ish.

The flowers are just starting.
Is now a 'good' time of year to trim them?

[David E. Ross]

Post by Danny D

Post by David E. Ross
If you think the hedge is overgrown, use a pruning saw to cut each plant
down to about 20 inches from the ground. Within a few months, it will
again be a hedge.

My wife loves the white flowers but it's crowding the driveway so I
have to lop off a foot or more to trim it back on the sides.
On the top, I just want it to look neat'ish.
The flowers are just starting.
Is now a 'good' time of year to trim them?

It will not bloom continuously all summer. Wait until it stops blooming
before cutting it.

[Vic Smith]

Post by Danny D

Post by David E. Ross
If you think the hedge is overgrown, use a pruning saw to cut each plant
down to about 20 inches from the ground. Within a few months, it will
again be a hedge.

My wife loves the white flowers but it's crowding the driveway so I
have to lop off a foot or more to trim it back on the sides.

Just trim off branches that encroach the driveway.

Post by Danny D
On the top, I just want it to look neat'ish.

Looks fine to me. If you get a "loner" branch trying to grab too
much attention, use this.
http://www.amazon.com/Fiskars-9240-Telescoping-Pruning-Stik/dp/B00004TBMV/ref=cm_cr_pr_product_top
That "wild" look suits me, and you don't have much choice with
oleander anyway.

[Danny D]

Post by Vic Smith
use this.
Fiskars-9240-Telescoping-Pruning-Stik

I do have one of those:
http://www2.picturepush.com/photo/a/12898805/img/12898805.jpg

The fiberglass pole is cracked, but still serviceable.

[The Daring Dufas]

Post by Danny D
Trimming question ...
http://www2.picturepush.com/photo/a/12891035/img/12891035.jpg
The trimmer is (way) too small to make the tops flat of my
Oleander bush.
I can't get the 20-inch blade across the top, while standing on
a step ladder, from the one side. The problem is that the other
side is wholly inaccessible to a ladder, so I can only trim the
top of the bush from one side.
http://www1.picturepush.com/photo/a/12891079/img/12891079.jpg
The Oleander bush is something like five or six feet across,
and something like nine or ten feet tall, for something like
a few hundred feet along a cliff-like extremely steep hill.
I can easily climb up on a step ladder to cut the side, but,
I can only lean over about three or four feet across the top
with the puny 20-inch 21.2cc hedge trimmer - and even that is
risky because one fall could be dangerous with a hedge trimmer
(I've already sliced my thigh with the thing in the past).
So, I'm mostly asking if there are better ideas for how to
cut the top of a tall and thick Oleander bush when you can only
access it from one side, and when your trimmer is 20 inches
while the bush width is at least three times that.
http://www2.picturepush.com/photo/a/12891105/img/12891105.jpg
Any helpful suggestions?

10kw LASER should do it, just be careful what's on the other side. ^_^

TDD

[Danny D]

Post by The Daring Dufas
10kw LASER should do it, just be careful what's on the other side. ^_^

I like the idea of a laser hedge trimmer, but I was really thinking
more along the lines of some kind of mechanical extension to my
puny 20 inch blades!

[h***@sbcglobal.net]

Post by Danny D

Post by The Daring Dufas
10kw LASER should do it, just be careful what's on the other side. ^_^

I like the idea of a laser hedge trimmer, but I was really thinking
more along the lines of some kind of mechanical extension to my
puny 20 inch blades!

PUT A HEDGE TRIMMER ON A PVC PIPE EXTENSION - It doesn't get any
wimpler than that.

[Oren]

Post by Danny D
more along the lines of some kind of mechanical extension to my
puny 20 inch blades!

Use those leftover pool poles........

[Danny D]

Post by Oren
Use those leftover pool poles........

:)

Actually, if there were a way to extend reach,
it would work!

[Oren]

Post by Danny D

Post by Oren
Use those leftover pool poles........

:)
Actually, if there were a way to extend reach,
it would work!

Duct Tape. Half a role should hold it on an ol' pool pole.

What do you need, a string for a throttle?

[Dan Espen]

Post by Danny D

Post by The Daring Dufas
10kw LASER should do it, just be careful what's on the other side. ^_^

I like the idea of a laser hedge trimmer, but I was really thinking
more along the lines of some kind of mechanical extension to my
puny 20 inch blades!

Try:

"long reach hedge pole trimmer".

Lots of hits.

[Ashton Crusher]

Post by Danny D
Trimming question ...
http://www2.picturepush.com/photo/a/12891035/img/12891035.jpg
The trimmer is (way) too small to make the tops flat of my
Oleander bush.
I can't get the 20-inch blade across the top, while standing on
a step ladder, from the one side. The problem is that the other
side is wholly inaccessible to a ladder, so I can only trim the
top of the bush from one side.
http://www1.picturepush.com/photo/a/12891079/img/12891079.jpg
The Oleander bush is something like five or six feet across,
and something like nine or ten feet tall, for something like
a few hundred feet along a cliff-like extremely steep hill.
I can easily climb up on a step ladder to cut the side, but,
I can only lean over about three or four feet across the top
with the puny 20-inch 21.2cc hedge trimmer - and even that is
risky because one fall could be dangerous with a hedge trimmer
(I've already sliced my thigh with the thing in the past).
So, I'm mostly asking if there are better ideas for how to
cut the top of a tall and thick Oleander bush when you can only
access it from one side, and when your trimmer is 20 inches
while the bush width is at least three times that.
http://www2.picturepush.com/photo/a/12891105/img/12891105.jpg
Any helpful suggestions?

Automatic Shotgun with the 100 round drum.

[Oren]

Post by Ashton Crusher

Post by Danny D
Any helpful suggestions?

Automatic Shotgun with the 100 round drum.

Danny lives in California. That solution is null.

[Norminn]

Post by Danny D
Trimming question ...
http://www2.picturepush.com/photo/a/12891035/img/12891035.jpg
The trimmer is (way) too small to make the tops flat of my
Oleander bush.
I can't get the 20-inch blade across the top, while standing on
a step ladder, from the one side. The problem is that the other
side is wholly inaccessible to a ladder, so I can only trim the
top of the bush from one side.
http://www1.picturepush.com/photo/a/12891079/img/12891079.jpg
The Oleander bush is something like five or six feet across,
and something like nine or ten feet tall, for something like
a few hundred feet along a cliff-like extremely steep hill.
I can easily climb up on a step ladder to cut the side, but,
I can only lean over about three or four feet across the top
with the puny 20-inch 21.2cc hedge trimmer - and even that is
risky because one fall could be dangerous with a hedge trimmer
(I've already sliced my thigh with the thing in the past).
So, I'm mostly asking if there are better ideas for how to
cut the top of a tall and thick Oleander bush when you can only
access it from one side, and when your trimmer is 20 inches
while the bush width is at least three times that.
http://www2.picturepush.com/photo/a/12891105/img/12891105.jpg
Any helpful suggestions?

I would have them cut to a manageble size, if possible. There are chain
saws that operate on long handles, used to trim limbs from
ground...would that work?

[Danny D]

There are chain saws that operate on long handles,
used to trim limbs from ground...would that work?

That might work better than these long-poled trimmers:

Loading Image...

Those don't work well with the oleander bush as the
branches sway too much for a good bite.

[Norminn]

Post by Danny D
Trimming question ...
http://www2.picturepush.com/photo/a/12891035/img/12891035.jpg
The trimmer is (way) too small to make the tops flat of my
Oleander bush.
I can't get the 20-inch blade across the top, while standing on
a step ladder, from the one side. The problem is that the other
side is wholly inaccessible to a ladder, so I can only trim the
top of the bush from one side.
http://www1.picturepush.com/photo/a/12891079/img/12891079.jpg
The Oleander bush is something like five or six feet across,
and something like nine or ten feet tall, for something like
a few hundred feet along a cliff-like extremely steep hill.
I can easily climb up on a step ladder to cut the side, but,
I can only lean over about three or four feet across the top
with the puny 20-inch 21.2cc hedge trimmer - and even that is
risky because one fall could be dangerous with a hedge trimmer
(I've already sliced my thigh with the thing in the past).
So, I'm mostly asking if there are better ideas for how to
cut the top of a tall and thick Oleander bush when you can only
access it from one side, and when your trimmer is 20 inches
while the bush width is at least three times that.
http://www2.picturepush.com/photo/a/12891105/img/12891105.jpg
Any helpful suggestions?

Landscape plants are not desireable if not manageable, so need to get it
to where you can care for it or have it cared for without killing
yourself. Is the entire row of bushes accessible from the ground? If
so, I'd cut out (at the base) about 1/3 of the limbs. After that, have
someone cut them down to a workable height (or a little lower, so you
can still reach to cut them. They are very, very had to kill....in
Florida, when they become overgrown, the practice is to just take a
chain saw to them. You can cut them back severely and they do fine. If
they don't bloom enough, buy your wife something from a florist or
she'll be putting flowers on your grave. IMO, flowers are kind of like
antiques....if they don't survive and thrive according to the conditions
I place them in, it is no loss :o)

I'm busy landscaping my new yard, koi pond and veggie garden....hell of
a lot of work, but if I didn't enjoy it I would not do it. I'm planting
landscape plants, partly for privacy at their full, natural and desired
size, care needs and appearance. Learn what plants need, how to take
proper care and they will be much less work. Example: got lots of trees
and leaves to rake? Use the leaves for mulch on azaleas and
rhododendrons...healthy for them and less work than bagging.

[Norminn]

Forgot the link: http://okeechobee.ifas.ufl.edu/MG34800.pdf

You do know that oleanders are poisonous?

[Danny D]

Post by Norminn
Forgot the link: http://okeechobee.ifas.ufl.edu/MG34800.pdf

Nice PDF. Interesting that the name comes from looking similar to
olive leaves and bay laurel leaves, both of which grow well on my
property so I'm intimately familiar with both.

Post by Norminn
You do know that oleanders are poisonous?

Interesting that only 10 grams of leaves can kill an animal
via an effect similar to that of digitalis.

The article says "direct contact with people should be avoided".
What does *that* mean? Clearly one wouldn't eat the leaves,
although I do suck on a bay laurel leaf or two while hiking.

But, what's direct contact. Is trimming 100 yards of tall bush
considered direct contact? I certainly hope not.

[Norminn]

Post by Danny D

Post by Norminn
Forgot the link: http://okeechobee.ifas.ufl.edu/MG34800.pdf

Nice PDF. Interesting that the name comes from looking similar to
olive leaves and bay laurel leaves, both of which grow well on my
property so I'm intimately familiar with both.

Post by Norminn
You do know that oleanders are poisonous?

Interesting that only 10 grams of leaves can kill an animal
via an effect similar to that of digitalis.
The article says "direct contact with people should be avoided".
What does *that* mean? Clearly one wouldn't eat the leaves,
although I do suck on a bay laurel leaf or two while hiking.
But, what's direct contact. Is trimming 100 yards of tall bush
considered direct contact? I certainly hope not.

Contact is touching, eating or breathing - think poison ivy. You might
be able to prune without touching, but sure would not dive into the
shrub to cut by hand. Chainsaws are nice. From what I have seen around
the 'hood in Florida, people tend to allow oleander to become overgrown
and then get out the chain saw (usually hired help). They are hard to
kill there, and cutting down severely doesn't seem to harm them. As
with many other shrubs, cutting out 1/3 of the oldest limbs/branches
each year keeps them fairly full and easier to trim.

[Danny D]

Post by Norminn
Contact is touching, eating or breathing - think poison ivy.

Hmmm... I have had some experience with chainsawing poison oak,
having tunneled through a jungle of the stuff for about 500
linear feet on a steep hillside (cutting a swath about 3 feet
wide, leaving overhanging vines about a foot above eye level).

I've also trimmed the 300 feet of oleander, about two years
ago, (not very successfully though, due to the top of the
bush being too high and wide for my puny 20" trimmer).

Having said what my experience level is, I wouldn't put them
on the same threat level ...

But maybe I'm missing something important.

[Oren]

Post by Danny D

Post by Norminn
You do know that oleanders are poisonous?

Interesting that only 10 grams of leaves can kill an animal
via an effect similar to that of digitalis.
The article says "direct contact with people should be avoided".
What does *that* mean? Clearly one wouldn't eat the leaves,
although I do suck on a bay laurel leaf or two while hiking.

Contact with the oils. IIRC white like sap that runs after you cut the
branches. Some communities have banned oleanders from being planted.
Folks get allergies from them.

"...Oleander poisoning occurs when someone sucks nectar from the
flowers or chews leaves from the oleander or yellow oleander plant.
Poisoning can also happen if you eat honey made by bees that used the
oleander plant for nectar."

<http://www.healthcentral.com/allergy/h/oleander-allergy.html>

[David E. Ross]

Post by Norminn
Forgot the link: http://okeechobee.ifas.ufl.edu/MG34800.pdf
You do know that oleanders are poisonous?

All reports that I have seen regarding oleander poisoning involved
ingesting. That is not limited to merely eating the leaves and flowers.
It includes people who vandalize oleanders in public parks to use the
thin but stiff long branches as skewers for barbecuing hot dogs and
roasting marshmallows. While such poisonings do occur, death is
extremely rare since oleanders are quite bitter and thus discourage
anyone from consuming a fatal dose.

A notorious homicide trial in southern California many years ago
involved a mortician who was accused of killing a business rival by
serving him oleander soup. Supposedly, the meal involved a
reconciliation. I guess the soup had sufficient seasonings to mask the
bitterness of the oleander. The accused was found "not guilty".

Oleanders are still planted in public parks and around schools because
they are so durable and the risk of poisoning is so minimal. At least,
they were planted until blight started killing them.

I must point out that many plants used for food are poisonous.

* A leaf from a peach tree can kill a small child. The kernel inside
the pit can kill an adult. Both contain cyanide.

* Leaves from rhubarb are toxic. But the leaf ribs are okay if
properly cooked.

* The raw source of tapioca (cassava root) is very poisonous. Natives
in South America put the juice in streams and ponds to kill fish, which
they then gather and eat.

* Natal plum (a close relative of oleander) is toxic except for the
ripe fruit.

* Apple and pear seeds are poisonous. Swallowed whole, they are okay;
but chewed, they can make you ill.

[Danny D]

Post by Norminn
Is the entire row of bushes accessible from the ground?

I'm not sure what you mean, but, yes, I can walk the entire
100-yard length of the oleander bush, if that's what you mean.

I can only walk on one side though - as the other side is a
cliff-like hill.

Post by Norminn
You can cut them back severely and they do fine.

This is good to know since I will be needing to cut at least
a foot or two off the sides, and maybe the same amount off
the tops.

Post by Norminn
Use the leaves for mulch on azaleas and rhododendrons...
healthy for them and less work than bagging.

I do have a compost pit that I've been putting all my
kitchen scraps in.
Loading Image...

[HeyBub]

Post by Danny D
Trimming question ...
http://www2.picturepush.com/photo/a/12891035/img/12891035.jpg
The trimmer is (way) too small to make the tops flat of my
Oleander bush.
I can't get the 20-inch blade across the top, while standing on
a step ladder, from the one side. The problem is that the other
side is wholly inaccessible to a ladder, so I can only trim the
top of the bush from one side.
http://www1.picturepush.com/photo/a/12891079/img/12891079.jpg
The Oleander bush is something like five or six feet across,
and something like nine or ten feet tall, for something like
a few hundred feet along a cliff-like extremely steep hill.
I can easily climb up on a step ladder to cut the side, but,
I can only lean over about three or four feet across the top
with the puny 20-inch 21.2cc hedge trimmer - and even that is
risky because one fall could be dangerous with a hedge trimmer
(I've already sliced my thigh with the thing in the past).
So, I'm mostly asking if there are better ideas for how to
cut the top of a tall and thick Oleander bush when you can only
access it from one side, and when your trimmer is 20 inches
while the bush width is at least three times that.
http://www2.picturepush.com/photo/a/12891105/img/12891105.jpg
Any helpful suggestions?

Pole-trimming chain saw.

<https://www.google.com/search?q=pole+trimmer+chain+saw&rlz=1C1PRFB_enUS513US513&aq=0&oq=pole+trimming+chain+&aqs=chrome.1.57j0l3.8226j0&sourceid=chrome&ie=UTF-8>

I got one from HD a couple of years ago; I think I paid about $90.

From the ground, I can reach upwards about 20'.

It works swell for the jobs between a lopper and a big chain saw and will,
no doubt, solve your problem.