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Eucalyptus and Nothing Grows?!

Posted by bearstate 9 CA (My Page) on
Wed, Aug 8, 07 at 19:15

A recent phone conversation between myself and an old friend touched on Eucalyptus Trees and how due to something the tree exudes, nothing will grow within a certain distance from the tree.

Now I don't thing that 'nothing' is the last word here, but apparently, a lot of things won't grow and I'm very curious to know more about this as Eucalyptus are a member of the 'Myrtle' family and I have many Crepe Myrtles growing around here and I've already found from surfing the web, that Crepe Myrtles also exude oils, but thusfar have found no mention of properties of those oils that would stymie or inhibit the growth of other plants.

I was told that once you have a Eucalyptus, the ground remains toxic for quite some time and the only thing that can be done is to actually replace the soil?!!!

So questions, questions, questions ....

1) What Will grown under Eucalyptus?

2) What is the substance and what is its lifetime in the soil?

3) Do Crepe Myrtles exude this substance?


Follow-Up Postings:

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RE: Eucalyptus and Nothing Grows?!

There is no real evidence that shows that Eucalyptus are "allelopathic" (exuding soil toxins). It seems to be a myth.

The real problem with Eucalyptus is threefold:

1. The roots suck water and nutrients from the surrounding soil, so much so that new plants have a hard time competeing.

2. The trees (mostly Eucalpytus globulus) cas dense shade and but a few plants grow in such shade.

3. Shear biomass -- large Eucs drop great quantities of leaves, burying little guys, and often great quantities of larger bulk (whole branches) that break even big stuff planted below.

There are some plants that do better than others other a Euc:

Large Shrubs, Small Trees--

Acacia longifolia SYDNEY WATTLE
Arctostaphylos MANZANITAS
Callistemon citrinus LEMON BOTTLEBRUSH
Cotoneaster COTONEASTER
Escallonia ESCALLONIA
Heteromeles arbutifolia TOYON
Melaleuca nesophila PINK MELALEUCA
Myoporum laetum COAST SANDALWOOD
Myrica californica PACIFIC WAX MYRTLE
Nerium oleander OLEANDER
Pittosporum undulatum VICTORIAN BOX
Rhamnus californica COFFEEBERRY
Xylosma congestum SHINEY XYOLOSMA

Medium Shrubs--

Abelia x grandiflora ABELIA
Arctostaphylos MANZANITAS
Cistus ROCKROSES
Correa AUSTRALIAN FUCHSIAS
Cotoneaster COTONEASTER
Escallonia ESCALLONIA
Fatsia japonica JAPANESE ARALIA
Galvesia speciosa ISLAND SNAPDRAGON
Juniperus JUNIPERS
Mahonia aquifolium OREGON GRAPE
Nandina domestica HEAVENLY BAMBOO
Nerium oleander OLEANDER
Pittosporum tobira TOBIRA
Rhaphiolepis umbellata INDIAN HAWTHORNE
Ribes sanguineum glutinosum PINK-FLOWERING CURRANT
Rosmarinus officinalis ROSEMARY
Viburnum tinus LAURUSTINUS
Westringia COAST ROSEMARY

Small Shrubs--

Cistus ROCKROSE
Correa AUSTRALIAN FUCHSIA
Escallonia ESCALLONIA
Mimulus aurantiacus and hybrids BUSH MONKYFLOWER
Nandina domestica HEAVENLY BAMBOO
Pittosporum tobira Wheelers Dwarf DWARF TOBIRA
Rhaphiolepis umbellata INDIAN HAWTHORNE
Sollya heterophylla AUSTRALIAN BLUEBELL CREEPER

Large Perennials--

Acanthus mollis BEARS BREECH
Dietes vegeta FORTNIGHT LILY
Elymus condensatus BLUE WILDRYE
Phormium tenax NEW ZEALAND FLAX

Small to Medium Perennials--

Agapanthus LILY-OF-THE-NILE
Aristea ecklonii BLUE STAR IRIS
Asparagus (many) ASPARAGUS "FERN"
Bergenia cordifolia PIGS SQUEAK
Clivia miniata KAFFIR LILY
Dianella tasmanica FLAX LILY
Helleborus lividus corsicus CORSICAN HELLEBORE
Hemerocallis DAYLILIES
Heuchera maxima CORAL BELLS
Liriope LILY TURF
Muhlenbergia rigens DEER GRASS
Nephrolepis cordifolia SOUTHERN SWORD FERN
Pelargonium GERANIUMS
Penstemon BEARDTONGUES
Phormium tenax (dwarf cultivars) NEW ZEALAND FLAX

Ground Covers--

Aptenia cordifolia RED APPLE
Arctostaphylos TRAILING MANZANITAS
Coprosma kirkii TRAILING COPROSMA
Cotoneaster TRAILING COTONEASTERS
Duchesnea indica MOCK STRAWBERRY
Hedera IVIES
Juniperus TRAILING JUNIPERS
Mahonia repens CREEPING BARBERRY
Myoporum parvifolium TRAILING SANDALWOOD
Ophiopogon japonicus MONDO GRASS
Vinca major TRAILING PERIWINKLE

Vines--

Distictis TRUMPET VINES
x Fatshedera lizei BOTANICAL WONDER
Hardenbergia violacea WINTER WISTERIA

Hedges/Screens--

Acacia longifolia SYDNEY WATTLE
Callistemon citrinus LEMON BOTTLEBRUSH
Hakea suaveolens SWEET HAKEA
Juniperus JUNIPERS
Ligustrum japonicum JAPANESE PRIVET
Myoporum laetum COAST SANDALWOOD
Myrica californica PACIFIC WAX MYRTLE
Nerium oleander OLEANDER
Pittosporum eugenioides WAVY-LEAF PITTOSPORUM
Pittosporum tobira TOBIRA
Prunus ilicifolia HOLLYLEAF CHERRY
Rosmarinus officinalis ROSEMARY
Viburnum tinus LAURUSTINUS
Westringia COAST ROSEMARY
Xylosma congestum SHINEY XYLOSMA

Joe


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RE: Eucalyptus and Nothing Grows?!

  • Posted by bahia SF Bay Area (My Page) on
    Thu, Aug 9, 07 at 0:09

I would second Joe's explanation of root and water competition, heavy debris being shed constantly by some species such as E. globulus, and shade. I would put the most emphasis of the root competition and drying out of soil, but the piling up of debris over time can also be considerable... Don't forget that in Australia where Eucalyptus are native there are many, many understory plants that are part of a diverse plant community.

in my experience locally, Toyon seems to be one of our California natives that best tolerates growing under dense Eucalyptus globulus, as does Poison Oak. Dianella tasmanica is also well adapted to root competition, and is a native understory plant to Euc. globulus in habitat.


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RE: Eucalyptus and Nothing Grows?!

Joe,

I think you are wrong. It's not a myth.

Park Rangers in the National Rec Area north of the Golden Gate Bridge in the Marin Headlands, California actually tell tourists during guided tours about the properties of Eucalyptus that do this.

There are several articles to be found on the web regarding the allelopathic properties of Eucalyptus, the worst imaginable, being an article about using Eucalyptus as mulch!

And unfortunately, I have found sever web pages that identify Crepe Myrtle as Allelopathic. My nursery for new seedlings is on my patio and there are two Crepe Myrtles growing there. I don't think my germination failures have thus far been due to the Crepe Myrtles since all seeds were sewn in store bought mulch, free of any leaf litter from the trees. But it is surprising to learn that my Crapes may be hazardous to any new plant introductions I might try near them. If they just affect germination, I can deal with that in controlled environmental setups for germination, but if they affect growth and development of certain plants, it would pay to know what is susceptible to avoid loss of investment in time, effort and money.

It's a shame ... Crapes are such pretty trees ...

See the following Wiki Article which states that Eucalyptus leaf litter and root exudates are allelopathic ...

Here is a link that might be useful: Mention of Eucalyptus Allelopathy.


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RE: Eucalyptus and Nothing Grows?!

Actually, that Wikipedia article is wrong. It is not based on any research (none cited); it is simply heresay -- bad information that has been floating around for years, including in many articles on the web that are non-scientific. These many articles simply perpetuate this unsubstantiated information.

There are research summaries that have been published on the web. Do a google search and track down those actual research pieces -- written by folks with PhD's at the ends of their name.

I won't comment on Crape Myrtle allelopathy. Never heard of such -- neither for or against.

Joe


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RE: Eucalyptus and Nothing Grows?!

Joe ... it doesn't take much to find white papers on the topic.

Here are just a couple on Allelopathic Eucalyptus:

http://edis.ifas.ufl.edu/HS186

James J. Ferguson, professor, Bala Rathinasabapathi, associate professor, Horticultural Sciences Department, Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, 32611

http://www.dfg.ca.gov/bdb/cwhr/pdfs/EUC.pdf

McArthur, A.G. 1962
Smith, G. A. 1980

And here is a reference table for US Forest Service and University of Hawaii on Crepe Myrtle, checking it off as allelopathic:

http://www.hear.org/pier/wra/pacific/lagerstroemia_indica_htmlwra.htm

There's more out there, but ... this'll do to give you your authoritative refs.

There is also an article I found out there that covers a survey of plants used in California Government ( City, County and State ) landscaping and Eucalyptus shows up as discontinued use due to allelopathic and other reasons. Oddly, Crape Myrtles are commonly used, and I assume ( making an ASS out of U & ME ) that this may be because the allelopathic nature of the Crepe Myrtle is not great or is unstudied. Else, Crepe Myrtle are so damned attractive that their allelopathic drawbacks are overlooked and they are used prolifically regardless. Who's to say?

For my part, allelopathic properties in plants is as new as yesterday when I first read your reply to my post. And yes, I'm a bit concerned as to how to adapt to this new found knowledge and this new word in my lexicon. I suspect that there are many other allelopathic plants out there now. What they are and how they affect my landscaping, gardening and hobbying with plants is a black hole as it likely is for most folks.

So now when I see a plant die or a seed fail to germinate, I have to ask a whole new set of questions. Was it heat? Not enough water? Poor soil? Bad seed? Birds got my seed? Gophers? Some chemical in the soil? Some allelopathic substance from ... that ...

What an adventure?!


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RE: Eucalyptus and Nothing Grows?!

  • Posted by dicot Los Angeles (My Page) on
    Fri, Aug 10, 07 at 15:23

Pulled from the web:

Studies conducted by Cornelius H. Muller and his graduate students during the 1970s indicate that terpene chemicals present in the resinous foliage and fallen leaves of chaparral shrubs inhibit germination of wildflower seeds, a phenomenon known as allelopathy. Fire destroys these inhibitory chemicals that have leached into the soil, and explains the abundance of wildflowers in recently burned chaparral. Salvia leucophylla, Salvia apiana, Artemisia californica, Adenostoma fasciculatum (chamise), and Trichostema lanceolatum are all considered "alleopathic" to some degree.


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RE: Eucalyptus and Nothing Grows?!

Did you try soil improvement with compost? When I first started I got terrible results no compost, then I started added it, and things got better, and better. I have a friend with a Eucalyptus she has the same problem, nothing grows, but she never did add compost. My theory untested, that over all soil improve will off set, but probably not completely the toxic from the Eucalyptus. It won't hurt at any rate.


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RE: Eucalyptus and Nothing Grows?!

It's definitely not true that NOTHING will grow under Eucalyptus...near my house there's a clump of them with, sadly, scotch broom and poison oak growing underneath. On a recent hike on Montara mountain, I noticed that in the understory of a eucalyptus grove coffeeberry and california hazelnut survived, too.

I read once that some people spread eucalyptus chips to discourage weeds, but that if they have any effect beyond just being nice-smelling mulch, it dissipates after three months. So if there is a toxin, it apparently doesn't really persist after the trees are removed.


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RE: Eucalyptus and Nothing Grows?!

I had considered that the exudant was bio-degradable and that the story of having to remove and replace soil was overkill. However ...

There's actually a forum at GW for Allelopathy.

There's at least one post there where a person has a big old 'historical' Euc in the middle of a street median that partially covers the person's property. And their attempts to beautify their own property have met time and again with failure. The suggestion of replacing soil has become all too real for them, including putting boxes and other contrivances up.

The thing too is that the exudates not only come from leaf fall, but from the roots of the Euc, which if near surface is a constant problem.


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RE: Eucalyptus and Nothing Grows?!

  • Posted by bahia SF Bay Area (My Page) on
    Tue, Aug 14, 07 at 1:12

Bearstate,
You seem to have totally disregarded that your so-called alleopathy might just be root competition for soil moisture and dense tree litter smothering young plants. I am certain that if you rake up all the larger litter that can bury the plants, but leave it as mulch around your understory plants, and provide drip emitters to new plants so that they never dry out, you can get shade tolerant plants established under Eucalyptus. But you don't sound the type to be convinced by people with actual experience...


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RE: Eucalyptus and Nothing Grows?!

What you seem to be missing is that I don't have a Euc. I have only heard about nothing growing under Eucs and then discovered that they are in the Myrtle Family. I have a lot of Crepe Myrtles here and there are plant databases on the web that show them to be allelopathic. Further, I have other plants growing here abouts that I now know are allelopathic and who knows what others may be.

I am just looking to learn something here about allelopathy and ... yes, how it applies to plants that may affect my situation here. To date, I am not aware of anything dying from my Crepe Myrtles. But I gotta tell you, I can see that when something does die or fail to germinate, there are a lot of variables, heat, not enough water, too much water, molds, viruses, too much sun, too little sun, too much fertilizer, too poor soil, spilled household chemical products, insects, ground hogs, birds and now, I learn ... other plants.

Forgive me for trying to understand the environment in which I am attempting to sew my seeds and in which I am trying to both hobby plants and do some landscaping. I'm here to learn about the ground I sew.

What a clown I think I'd be if I mulched my seed starters with stuff from an allelopathic plant and then sat around wondering if I just got a bad batch of seeds?!


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RE: Eucalyptus and Nothing Grows?!

  • Posted by bahia SF Bay Area (My Page) on
    Tue, Aug 14, 07 at 23:44

Lagerstroemia indica is not in the same family as Eucalyptus, they are not Myrtacea. I have several Lagerstroemia x fauriei hybrids in my own garden, and have never noticed any problem with growing plants below them, and have many things that self sow regularly in the area below them that would have leaf mulch from the trees. You wouldn't want to start young seedlings of anything in an area where they would be inundated with lots of falling leaves, while in the garden with plants that self sow as volunteers, they seem to sort this out without any issues.


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RE: Eucalyptus and Nothing Grows?!

  • Posted by socal23 USDA10/Sunset23 (My Page) on
    Wed, Aug 15, 07 at 23:34

Bearstate,

There are only a few instances were allelopathy is generally accepted, Eucalyptus isn't one of them. This is one of those things that "everyone knows" that if not flat out wrong, is at least overly simplistic.

The fact is, any plant that will tolerate shade and intense root competition can be established under a Eucalyptus provided roots are kept out until the plant is established (no mean feat, Dave Fross of Native Son's Nursery says that roots from the trees that surround his property used to grow up into his potted plants before he started putting the pots on landscape fabric).

Misinformation surrounds us and has made fools of everyone on one occasion or another. On an almost daily basis I cringe at statements made by even intelligent, well-educated people.

For example, "everyone knows" that fire suppression efforts are responsible for the destructive fires that we have dealt with over the last several years in Southern California, after all, every time there's a fire we hear reporters and politicians saying it. The fact is that the plant community most of these fires have occurred in, chaparral, is not pine or fir forest adapted to relatively cool surface fires. Chaparral burns from crown to ground every single time whether the fire frequency is once in 5 years or once in 200 years. Naturally occurring chaparral fires are relatively uncommon: the fires down here are overwhelmingly human caused (naturally occurring fires would also tend to occur in midsummer under the influence of the southwest monsoon rather than during the Santa Ana season).

Ryan


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RE: Eucalyptus and Nothing Grows?!

  • Posted by dicot Los Angeles (My Page) on
    Thu, Aug 16, 07 at 1:18

Ryan, I disagree with both the content and tone of your post. The primarly oil from most eucalyptus species - eucalyptol -is a cyclic ether and a monoterpene. The four most comomon horticultural monoterpenes - camphor, eucaliptol, limonene, and -pinene - have been shown in peer reviewed studies to inhibit seed germination at higher concentrations and decrease the oxidative metabolism of associated mitochondria.

While it is not true that nothing grows under eucs, neither is it misinformation that eucs have a negative chemical effect on seed germination. As a former Forest Service firefighter, I also believe you are oversimplifying the chapparal fire cycle and it is not an apt analogy to euc alleopathy.

Its fair to disagree with the above statements on alleopathy. Its condescending to talk about how you cringe at statements made by even intelligent, well-educated people.


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RE: Eucalyptus and Nothing Grows?!

  • Posted by socal23 USDA10/Sunset23 (My Page) on
    Thu, Aug 16, 07 at 1:46

Bearstate,

My apologies for any offense my post may have caused.

Marc,

Thanks for the civil tone, I appreciate it.

Ryan


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RE: Eucalyptus and Nothing Grows?!

  • Posted by socal23 USDA10/Sunset23 (My Page) on
    Thu, Aug 16, 07 at 2:15

Sorry about the double post, I wanted to defuse the situation before someone less patient than Marc chimed in.


"...cringe at statements made by even intelligent, well-educated people." Alas! Skewered by my own sword.

My post was the result of numerous short periods at the computer over several hours (things are a bit crazy around here right now).


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RE: Eucalyptus and Nothing Grows?!

SoCal23,

I don't find myself offended.

I do very much believe that allelopathy is a real problem to be considered when one is trying to germinate seeds and raise young sapling plants. Eucs are not the only source of allelopathic chemicals in the soil, but the story my freind shared with me about Eucs is how I first learned about this. Again, I do not have Eucs here. And someone pointed out above that Crepe Myrtles and Eucs are not in the same family as I was lead to believe when I heard Eucs are in the Myrtle family. Are they ... or are they not?


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RE: Eucalyptus and Nothing Grows?!

  • Posted by youreit z9b CA Sunset z8-9 (My Page) on
    Fri, Aug 17, 07 at 10:46

They are not, Bearstate. Crape myrtle (Lagerstroemia) is in the Lythraceae (loosetrife) family. Eucalyptus is in the Myrtaceae (myrtle) family.

To make matters even more clear (pshaw!), the plant commonly called loosestrife is in the primrose family. :D

Brenda


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RE: Eucalyptus and Nothing Grows?!

Confusing, isn't it?

And when all is said and done, web databases list Crepe Myrtle as having allelopathic properties all the same.

I'm not sure how to deal with allelopathy in plants right now, except to have an awareness and play it safe around the ones I know I have growing here, especially with seedlings that I've invested time in and with other plants that I've invested purchase price in.

It's an interesting curve ball for layman gardener and I'm sure lots of people ignore allelopathy and just muddle through happily come success or failure.


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RE: Eucalyptus and Nothing Grows?!

  • Posted by dicot Los Angeles (My Page) on
    Fri, Aug 17, 07 at 15:43

Bearstate, I don't think you should worry about it much at all - there must be a thousand other more likely garden problems than alleopathy. Especially if you do like most of us and start your seeds germinating in sterilized soil or soiless mixes seperately and grow them to transplanting size.

Like Bahia says, most people don't have problems under crepe myrtles. I would argue it isn't because alleopathy doesn't exist, but because the concentration of oils is low and somewhat water soluble, so regular irrigation helps diffuse any toxicity. You really have to get a lot of litter buildup for it to be noticable, so cleaning up the leaves should be more than enough if you are concerned.

Plants that have that strong odors usually have lots of terpenes (aromatic hydrocarbons) and these oils can have some limited effect in the soil. Remember when Reagan declared that pine trees cause pollution? That was the terpenes in the needles - needles that are used to make turpentine (hence, the name).

If you are really interested, try a test: create a compost with large amounts of Lagerstroemia leaves then try and germinate seeds in that mix and a standard mix under the same growing conditions and see what you get. It could be interesting.


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RE: Eucalyptus and Nothing Grows?!

  • Posted by sumcool Cen. Coast/s17 (My Page) on
    Tue, Aug 21, 07 at 18:43

Hmmm, these are very interesting posts.
I live around the corner from Native Sons Nursery and enjoy seeing all the wonderful plantings under their eucs.

Under the eucs in the "forest" on our property, there's a ground cover of vinca that thrives without care.
Also, we've planted cotoneaster (no soil amendment - drip watering for the first year) under some eucs in our garden and they're doing fine. I do think, though, that the plants need to be very tough to thrive with the shade, the droppings, and the insatiable rootlets. Thank you Joe for your advice before we planted.


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RE: Eucalyptus and Nothing Grows?!

We live 1.5 mi east of Torrey Pines State Beach in San Diego. I want to plant a grevillea guadichaudii under established eucalyptus trees, with very sandy soil. Should I go for it? The plant is pretty pricey. The only true success we've had under the trees is with acacia redolens.


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RE: Eucalyptus and Nothing Grows?!

  • Posted by youreit z9b CA Sunset z8-9 (My Page) on
    Sun, Sep 30, 07 at 10:26

Below is a list of Eucalyptus understory plants from San Marcos Growers which I posted on another thread but might be somewhat helpful to you. Your Grevillea isn't on the list, however neither is your Acacia, so...take from it what you will. :)

Brenda

Here is a link that might be useful: Eucalyptus Understory


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RE: Eucalyptus and Nothing Grows?!

No doubt Blue gum has alleopathy tendencies..to lump all Eucalypts is beyond science. As a matter of fact Blue Gum extract is so potent it is used in the place of antibiotics to treat many fish farm pathogens. Even then I have seen photos of Blue Gums in habitat and there was plenty of undergrowth right up to the trunk.
Interesting that I find tree ferns from the southern hemisphere thriving under African Podocarps in my yard. Podocarpus trees also are thought to be alleopathic.
When it comes to the Eucs,better to think native-native Australians!


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RE: Eucalyptus and Nothing Grows?!

My neighbors relandscaped earlier this year and put gazanias under their eucalyptus, and so far they look good. Not sure what kind of gazanias.


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RE: Eucalyptus and Nothing Grows?!

I just muddle through happily, come success or failure.

Personally, I have a number of Schinus and Eucalyptus trees in my yard. The only adverse affects I've noticed on nearby plants are the leaf litter cover produced. Doesn't kill the plants or anything, I just have to clean off the litter once a year. Both Eucalyptus and Schinus seem to have their main drop in the middle of summer (July). Because I have a steep, exposed hillside, some of the litter I appreciate because it helps alleviate erosion.

If I were to guess, based on my situation, I'd guess the biggest problem for surrounding plants would be water competition...followed by root competition. None of my surrounding plants have expressed any indications of poisoning of some sort.

A shame these trees have such a bad reputation. I like them.

A view into some Eucalyptus--

A view under a pepper tree--

Here's an interesting article on Eucalypt plantations and their affect on soil.

-Ron-

Here is a link that might be useful: Eucalyptus Plantations


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RE: Eucalyptus and Nothing Grows?!

I have had great success with oxalis under my eucalyptus. Crabgrass seems to do quite well too.
Renee


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RE: Eucalyptus and Nothing Grows?!

according to the University of California Master Gardeners Program folks, almost all plants are allotropic to some degree. It doesn't take a lot of observation to see that not many Euc's have something growing under them.
I suggest non plant objects under the tree, boulders, bird feeders, benches, and so forth.


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RE: Eucalyptus and Nothing Grows?!

Another problem with eucalyptus is its propensity to burn fiercely. An older tree can literally explode into flame during a fire. Unfortunately many homes in southern CA have big old eucalyptus trees growing right up against them.


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RE: Eucalyptus and Nothing Grows?!

  • Posted by socal23 USDA10/Sunset23 (My Page) on
    Fri, Nov 9, 07 at 23:29

JC,

Eucalyptus has gotten a very bad rap on that score and it is largely undeserved, not because they aren't flammable but because they aren't any more flammable than many other ornamental trees.

First there is the issue of which Eucalyptus you are referring to. The most prominent cautionary tale is the Oakland Firestorm of 1991 featuring the Tasmanian Blue Gum (naturally, the bogeyman sometimes used to vilify all Eucalyptus). What so many popular tellings of the story omit is the issue of fuel load. On top of the effects of severe drought, those trees had been severely damaged by the December 1990 freeze and had a tremendous volume of dead limbs in their canopies.

I've seen the effect of fire on normal healthy Blue Gums, while they do indeed burn (right along with the Avocado trees they were planted as a windbreak for), they don't normally explode into flames the way the trees in that fire did.

Ryan


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RE: Eucalyptus and Nothing Grows?!

I have had three large eucalyptus, (located in arizona) one in the middle of a lawn, the other two on the outskirts of a lawn --surrounded by bedding plants --and cactus on one side of one of the plants --near the one planted in the lawn, is a olive tree --no ill effects to any one of the plants or lawn --except shade --had to remove them --to big and danger to a structure which was placed their after the trees were planted --


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RE: Eucalyptus and Nothing Grows?!

I have eucalyptus trees that have been in place for 20-some years and I have never removed the leaf litter. Growing beneath them are cistus skanbergii, cistus creticus 'Lasithi', pennisetum setaceum 'rubrum', penstemon BOP, toyon, acacia, dietes, geranium incanum, salvia Indigo Spires, myoporum, and growing beneath the e.citriodora is tecomaria capensis. The plants beneath the tress have been in place for years and I use eucalyptus mulch.


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RE: Eucalyptus and Nothing Grows?!

I've had success with a number of plants growing under the three eucalyptus nicholii I have:

hebe
mahonia repens
berberis darwinii
ivy geranium
centranthus
miscanthus transmorrisonensis
Cleveland sage
Santa Barbara daisy
Ribes speciosum (fuchsia-flowering gooseberry)
Salvia Belize form
Argryranthemum "Silver lady"
Pittosporum "silver sheen"
Cape plumbago
Buddleia


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RE: Eucalyptus and Nothing Grows?!

I had Eucalyptus trees growing on my neighbors property on both sides of my property. Besides shading my property, the roots grew over 50 feet until they were under my garden and sucked the water out from underneath it. I tried growing a garden about ten feet away from one big clump of them but it wouldn't grow. Luckily both neighbors finally cut them down but they are growing back. A Euc can grow 20 feet in one year if it already has established roots from before it was cut down to a stump. I don't think they should allow blue gum or other large Eucs to be planted in suburban neighborhoods. There is one huge one growing about two hundred feet from my property and it blocks the sun out most of the afternoon in all seasons except summer. People don't think what a tree will look like or how big it will be twenty or thirty years later.
A tree trimmer just offered me 25 cubic yards of shredded Eucalyptus tree trimmings for free, but I turned him down, I didn't want to take a chance of poisoning my soil.


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RE: Eucalyptus and Nothing Grows?!

I wish he were close by and offered it to me, I'd grab it in an instant. We've had eucs on our property for 20-some years....very useful. We use only wood heat and we've never bought wood, the mulch from our trees is used everywhere on the property and I never have enough.


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RE: Eucalyptus and Nothing Grows?!

In Portugal, eucalyptus is our 2nd most common tree. It is not a invasive species per se, but it is highly planted and little grows under it, and creates a kind of "green" desert.

No animal life under it. And little plant life.

Thankfully, oaks, chestnuts, acacias and mimosa, can all grow under the eucalyptus if they have some clearing, and therefore start to regenerate the forest again. But a heavily planted eucalyptus forest usually only lets acacia (another invasive to spread inside the eucalyptus forest).

Other that that, heather, ivy, vinca are amongst the few to be able to grow under the eucalyptus. Blackberry is perhaps the only edible plant that sometimes grows (and rampant) into eucalyptus forests.

I can't say that eucalyptus is allelopathic, but definitively little grows under it, and it creates a desert in biodiversity. The soil under eucalyptus is usually very dry, poor and full of their thick leaves. The soil under a native forest (mostly oak and chestnut) is much more rich in humus, with humidity and thriving with other plants. Under pine the soil is usually dry, acidic and only with some native species (but not much). Under a acacia forest, usually there is much shade, humidity but very little biodiversity (due to perhaps the strong shading and single species forest)


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