g'day almeria,

i'm a supporter of folk growing trees native to their area and climate, as like over here exotics can become weeds.

anyhow to try and answer your question acacia and eucalypts will grow in close company if there is sufficient soil moisture, they then won't feel like competitors. if you could see some of our bush over here you would see what i mean.

now acacias will take pruning to keep them low and give them some shape not sure how they would go as a hedge, but pruning will help to keep them bushier and lower in height.

now having said that, these large eucalypts you have are they in a suburban type home garden situation? most of the eucalypt family are forest trees and are somewhat dangerous when planted to near homes and other structures etc.,. in storms they can fall over for almost no apparent reason and they shed large branches in much the same vain. all of which could be very harnmfull to humans and their homes.

the rule of thumb with an eucalypt is to grow it no closer than it's expected full height plus 50% eg.,. a 40 meter tree would have to be 60 meters away from home and over head utilities.

len

Here is a link that might be useful: lens garden page

Thanks very much, Len - even if you are scaring me to death!
The eucalyptus are only about 4 metres from where I sit writing and they are about 20 metres tall, so frankly I think our days may be numbered...
A lot of Australian natives do very well here but it is such a dry climate and the soil is so poor, I don't THINK anything is in danger of becoming a weed. Except maybe some of the (south African - I think) succulents. I am still waiting for something I've planted - anything I've planted - to manage to self-seed in my garden.
The area where the "hedge" screen would be will be on a drip system. The eucalypt don't have any additional water...or should they???
Thanks again for your help and for the link
Best wishes
Almeria

g'day almeria,

not doing it to scare just saying how it is, they are not garden or street trees over here for that very reason.

trees that high won't benefit from any watering you may do at the surface, they will have a tap root down into you sub-aquafa, but when it gets dry and they shed leaves those leaves usaully work toward stopping any other tree from growing as it may compete with the eucalypt.

so by keeping the surface are watered well enough this won't happen.

sucalypts have become weeds in places like california and madagascar, wher they grow and spread well because growing conditions aren't often as harsh and there are no natural pests to control their spread.

len

Almeria
I had never thought of growing a wattle (acacia) as a hedge
but I see absolutely no reason why it wouldn't work.
I have an A. longifolia which I pruned at the top and the spreading effect was tremendous.
The A. longifolia grows to much the same height as A. retinodes (correct) in its native habitat.
In hindsight I think the wattle would have made a terrific hedge. You would, of course, need to keep it trimmed.
Go for it I say.

Roy

Len and Roy
Thanks for your help and encouragement. I'm going to give the acacia a go.
Roy - I haven't much of an idea about how to prune wattle but I will do some reading up on the matter and thanks for the tip about pruning the top to get spread widthways. How big were your wattle when you did this, I wonder...
I haven't heard of eucalyptus being invasive in this area - though that doesn't mean they aren't. I was told that the eucalyptus seeds only germinate with very, very high temperatures - the kind you get in a forest fire. But that was obviously rubbish. Incidentally, the local council here recently cut down a group of about twenty eucalypt (for more development) and there was a bit of an outcry as there are so few trees here at all (mediterranean pine, eucalyptus, a few wattle, olives and a lot of palms. ) The council responded by saying "Well, they aren't indigenous to this area..." An interesting argument!
Thanks, Len, for the information about the eucalyptus and the acacia competing (or not) for water. We have 5 large eucalyptus in the main part of the garden and they seem to suck every bit of water and food out of the earth - plus making a solid network of fine roots throughout all the soil. To be honest, I find them a bit of a nightmare for growing anything else but they are so beautiful - and shady - that we would hate to be without them.
Thanks again for all your help
Almeria

Hello Almeria

I would be very happy with a wattle informal hedge. I was in my garden today. I planted an Acacia longifolia, grown from seed a year ago, and it already has flower buds on it. Isnt that wonderful.

I have had Acacia longifolia growing in the past, and I pruned it a lot to keep it compact and to reduce its height.

Do you know what sort of Eucs you have in your garden ?

Surely there must be some nice trees local to your area, that would make nice hedges.

Are Eucs a weed in Spain ?

All the best to you.

Popi

Almeria
My A. longifolia was about 2 metres tall and very spindly when I pruned the top.
It continued to grow upwards but also grew sideways.
I planted this shrub on 27 March 2005, when it was 1.2m tall and about 30cm wide.
Today, almost 15 months later it is 3.5 metres tall and 2 metres wide.
It has flower buds all over it and will be a mass of gold in about 6-8 weeks.
Good luck with your wattle.

Roy

Apparently the Eucalypts most prone to dropping large limbs are the smooth-barked ones. You are said to be safe with ironbarks, but I'd like to be more sure of this before planting them close to a house, all the same.
Yes, Almeria, the greedy roots thing is often complained of here, with people saying that there is no point watering under eucalypts to get other plants to grow, as all you're doing is watering the eucalypts.
There are more than a thousand species of eucalypt, including, some truly beautiful SMALL ones, with the western Australian mallees at the top of the list in my view. There are also some truly superb grafted eucalypts which should be quite safe near houses as they don't get very tall. You'd probably know already if you had any of these, by their extremely showy flowers.
You can see that none of us want you to grow an environmental weed, but don't let this put you off Australian plants, as there are literally thousands of them which would do well in your climate.
Before planting wattles, read up a bit on the lifespan, and see whether you're happy with what's on offer. There is a tendency for the showiest ones to be short-lived (ten years or so). Acacia decora is an exception.
What about the emu bushes, Eremophila species? Can you get them over there? Their botanic name means "desert-lovers". There are several hundred species. They are showy in flower, and many of them are also good screens. (e.g. Eremophila maculata.)
Trish