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PlantFiles: Silk Oak, Silky Oak, Silver-Oak
Grevillea robusta

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Family: Proteaceae (pro-tee-AY-see-ee) (Info)
Genus: Grevillea (grev-ILL-ee-uh) (Info)
Species: robusta (roh-BUS-tuh) (Info)

One vendor has this plant for sale.

3 members have or want this plant for trade.

Category:
Trees

Height:
over 40 ft. (12 m)

Spacing:
20-30 ft. (6-9 m)
30-40 ft. (9-12 m)
over 40 ft. (12 m)

Hardiness:
USDA Zone 9a: to -6.6 C (20 F)
USDA Zone 9b: to -3.8 C (25 F)
USDA Zone 10a: to -1.1 C (30 F)
USDA Zone 10b: to 1.7 C (35 F)

Sun Exposure:
Sun to Partial Shade

Danger:
Handling plant may cause skin irritation or allergic reaction

Bloom Color:
Gold (Yellow-Orange)

Bloom Time:
Mid Spring

Foliage:
Evergreen

Other details:
This plant is attractive to bees, butterflies and/or birds
Drought-tolerant; suitable for xeriscaping
Average Water Needs; Water regularly; do not overwater
This plant is resistant to deer

Soil pH requirements:
6.1 to 6.5 (mildly acidic)
6.6 to 7.5 (neutral)
7.6 to 7.8 (mildly alkaline)

Patent Information:
Non-patented

Propagation Methods:
From seed; direct sow outdoors in fall
Direct sow as soon as the ground can be worked
From seed; direct sow after last frost

Seed Collecting:
Allow pods to dry on plant; break open to collect seeds

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There are a total of 46 photos.
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Profile:

11 positives
8 neutrals
7 negatives

Gardeners' Notes:

RatingAuthorContent
Neutral KonaLance On Nov 18, 2013, KonaLance from KAILUA KONA, HI wrote:

We just purchased 3 acres on the Kona side of the Big Island of Hawaii. I am at 1,800 foot elevation, average about 60 inches of rain a year, and have at least 30 of these on our property. They sit amongst the native Ohia trees, Kukui nut trees, and Guava trees, most locals consider them "rubbish trees" but I like them. I once seen a home on the Hamakua side, where they used the wood for their flooring. I am thinking about doing this, any tips or hints from anyone?

Negative fensterlips On Jun 7, 2013, fensterlips from Windsor, CA wrote:

The neighbor behind us has a wall of 6 Silky Oaks and while they provide a good screen they are very very messy dropping absolutely tons of litter in seed pods, flowers and leaves.
It is attractive from a distance and I suppose makes a good alternative to Australian Gum trees - but doesn't almost anything?
Don't plant near a house or near an area desired to be reasonably clean. If it's an open area you want to see self-mulch and you don't mind constantly pulling up the self-seeded starts then go for it.
I think I'll pass.

Negative jenny74 On Aug 30, 2011, jenny74 from Adelaide
Australia wrote:

We live in suburban Adelaide and have an 80ft Silky Oak in our front yard which was planted in 1959 according to the neighbours. It has now reached "significant tree" status in our council area and we are unable to remove it without an arborist's report and council approval. So far, 2 arborists have deemed it healthy. We have the plumber out twice a year to unblock the pipes at a cost of $500 a pop- not a general pipe clean! The whole sewer needs replacing now and both bathroom floors are cracked from the roots. The tree constantly drops leaves, sticky sap, branches and looks completely scruffy. The neighbour is moving because it is less than 10 mtrs from her front door and she can't stand it anymore! I would never plant this tree unless I lived in the country!

Negative Halibobo On Feb 19, 2011, Halibobo from Tucson, AZ wrote:

We have a 23-year-old, 40 foot, silky oak in our front yard. Most of the time it is a very beautiful tree to look at, but the negatives far outweigh the positives.

Negatives: There are two or three months out of the year that it isn't dropping leaves, blooms, sap (oh, my, the sap is horrible!), or seeds. Very brittle branches.

Positives: Absolutely beautiful when it blooms, needs minimal water.

We had a windstorm a few years ago that sheared the branches off half of the tree. Not the top or bottom half, but the left half! A couple of weeks ago we had an abnormally hard freeze for Southern Arizona and I came home yesterday to my driveway almost ankle-deep in leaves from this tree. I am a little concerned that the tree is going to die. As much as I dislike the tree, I don't want is falling on my house or my neighbors!

Negative bobojuan On Dec 2, 2010, bobojuan from Fresno, CA wrote:

I live in California's Central Valley, Zone 9. This tree grows very tall and gets spindly and unattractive as it gets older. I had one located on the back of my property but had it cut down. The top of the tree was rotted so it was only a matter of time before a storm would have knocked it over. I have posted a photo showing the tree with a red arrow pointing out the height of the tallest electrical line in comparison. Seeds readily; I pulled up couple of volunteer seedlings from my front flower bed; also note the arrow pointing to a young silk oak in a neighbor's yard.

Neutral ljonestx On May 17, 2010, ljonestx from Palm Bay, FL wrote:

I just discovered your website! Great!
There were 2 silk oak trees on our property when we moved to FL in 1975. One was struck by lightening and had to be removed. Neither of them ever bloomed, that I remember. In 1986 we moved back to TX for 23 1/2 years. We have now bought a house in Palm Bay, FL and inherited a smaller silk oak tree in our front yard. It is beginning to bloom. I think I may be allergic to it...sneezing my head off right now! They are rather messy, leaf drop, seeds etc. But we love the shape and the flowers. Hope to keep it and would like to start one for the back yard.

Positive jinglehyme On Feb 11, 2010, jinglehyme from Pasadena, CA wrote:

I had an overgrown Red Gum reshaped today near my driveway. It had been topped by a previous owner and was growing in the most unnatrual (and dangerous) way - much to my delight the Gum-grooming exposed the real shape of the massive Greviella the had occasionally poked its blooms through the overgrowth of the Gum.

I love this tree! I had the aborists take out all the dead growth and broken limbs. It is spectacular! Nearly 40 feet high and very upright. I"m thinking of planting a few more to the southeast downsloping (rather steep) side of my property to screen the view of a recently built McMansion. I hope it is not a flamable as the Gum!

I live in a 1961 mid mod in the Linda Vista Neighborhood of Pasadena - The Grevellia seems to thrive here - we seldom get frost, the soil is well drained DG over solid granite. Replace a Gum today!

Neutral Cixi On Jan 25, 2010, Cixi from Addis Ababa
Ethiopia wrote:

I have one of these trees and it's getting too tall for the available space. Having read through comments from others, I gather that it's possible to cut the tree back to reduce its height. Since there are not many professional tree surgeons here, I'd be grateful for detailed advice on how best to do this (ie can several metres be removed at once, in which season should it be done, etc).

Negative DSpiely On Jan 19, 2010, DSpiely from Manhattan Beach, CA wrote:

I live in Manhattan Beach, CA. Our home, acquired in 2003, contains a Silk Oak in the front yard that we believe is over 30 years old. The tree was near 80' tall and we have had it cut back by about 10'. Shortly after moving in, I began to get rashes on my ankles -- the contact dermitis mentioned by others of greater authority than myself.

Neighbors tell us the original owners never trimed the tree, so it is now too big for the yard. It damaged our main sewer line which had to be replaced; drops leaves and sap everywhere, all the time. Today we had our first big branch fall off - about 10' section - fortuneately not hurting anyone or any property. This tree belongs on the plains of Australia, not in your front yard. We have strict tree ordinances, so it will be difficult for me to get permission to cut it down. The was some orange material oozing from the site of the branch breakage, so I am actually hoping it is now diseased so we can take it out.

Positive albey30 On Jan 11, 2009, albey30 from Christchurch
New Zealand (Zone 9a) wrote:

Hi there,
I live in a zone 9a climate, and there's a Grevillea robusta growing just up the road from me and it is approx 65-feet tall ( 20m ). Since then i have seen another 6 Grevillea robustas all over our city ranging from approx 6m to 15m ( 20 - 50 feet ). confirming that they grow in a 9a climate. ( We experience frosts down to -5 degrees celcius in our area ).

Negative txma On Jan 8, 2009, txma from North Shore
New Zealand wrote:

Had one of these removed from a rental property in Auckland NZ, only a few arbourists were willing to touch it.
Apparently the sap and bark are toxic, and cause skin and bronchial irritation.

Apart from that the plant was dropping branches in any wind more than moderate and clogging the guttering of the house all year round with it's leaf and flower detritus.

Burning the plant while not properly seasoned is also hazardous.

They do look nice on someone elses property, I would not want one on my own property.

Negative gryyn On Oct 25, 2008, gryyn from Santa Rosa, CA wrote:

Hi, I live north of san francisco , and I have to tell you this is a messy, ugly tree. I just had it cut down today! it was 45' tall and just crapped all over my deck, and my neighbors deck, all year round. It drops leaves, it drops flowers, it drops seeds. And it almost never looses all its seeds, so, The tree looks so shoddy. I have lived at my house for 6 years and I wanted to cut it down after the first year. I truly despised this tree. And now its gone, good riddens. Please, think twice if you plan to add this tree to your property. Take a look at this tree before you buy. Or, if you buy this tree, but a rake, you will need it.

Positive reesieo10 On Aug 19, 2008, reesieo10 from Zephyrhills, FL wrote:

I planted this tree about 4 years ago in my backyard. I live in Zephyrhills,FL ,33541- zone 9A (?). Our winters have dropped into the high 20's and this tree has survived. The leaves are fern-like and very attractive. My only disappointment is that the tree has not yet bloomed ( which is why I planted it in the first place to attract birds, butterflies,and hummingbirds) . Could anyone give me any ideas as to why it has't bloomed yet?? I planted the tree in front of some oak trees which minimally shade the tree during a small part of the day.The tree gets mostly sun to minimal part shade . .I would appreciate any feedback.
Thanks, Reesieo

Neutral htop On Jan 26, 2008, htop from San Antonio, TX (Zone 8b) wrote:

I have not grown this tree. Silk Oak, Silky Oak (Grevillea robusta) which is a native Ausralian tree has become naturalized in Florida, the Hawaiian Islands and Puerto Rico.

Positive Traxy On Sep 24, 2007, Traxy from San Marcos, CA wrote:

My soil is mostly decomposed granite but the trees have no trouble growing in it. The seeds actually seem to prefer this tough soil. I spend a lot of time pulling out seedlings all over the yard; yes, they are that prolific!

I trim off the bottom branches and that makes the trees great for shade.

I've also noticed that the roots seem to be very touchy about being disturbed during transplants. My success rate is very low and seems to be mainly the plants where I have a huge dirt ball around the roots.

Positive doodah On Aug 19, 2007, doodah from Menifee, CA (Zone 9a) wrote:

I love this tree, but . . . my silk oak is tall and spindly - looks like a Charlie Brown Christmas Tree! The top 8-10 feet has very few branches. Should I top the tree?

Positive Bayhomie On Apr 5, 2007, Bayhomie from San Diego, CA (Zone 9b) wrote:

My rear yard is a south facing canyon slope and is planted in citrus at the upper part near the house. About a year ago, to my amazement, I saw bright yellow-orange patches through the citrus trees that turned out to be the blossoms of a 20 Ft. tall Grevillia. The tree is a true volunteer and to my knowledge there are no other nearby specimens. I can't be sure how long it has been there, but not more than two or three years. I guess I'll let it grow since it seems to be so happy in its chosen home, which is also mine. If it keeps growing at the present rate it'll be a good climbing tree for my grandson.

Neutral palmbob On Feb 23, 2007, palmbob from Acton, CA (Zone 8b) wrote:

Extremely common landscaping tree here in Southern California.. a beautiful tree, but somewhat overused in our suburbs. This tree has the down side of having very brittle wood, and branches falling off for apparently no reason whatsoever are not uncommon events. It is heavy wood, too, though, so a lot of damage can occur when one of these branches crashes on your car or house. They seem to like to 'top' these trees here, perhaps for that reason.

Positive joanw7 On Feb 22, 2007, joanw7 from San Juan Capistrano, CA wrote:

I live in San Juan Capistrano, CA and finally yesterday found out from a tree expert hired to trim back some of our other trees-that the 50ft tree growing in the middle of the yard is called a Silk Oak. The tree popped up in the middle of our yard only four years ago and is growing like a weed. We thought it was just some cute little shrub at first so we let it grow. The second year tons of yellow & orange flowers with a sticky nectar covered the trees. We have many tropical birds that come to this area in the spring and they just went wild for the nectar-we never had so many birds in our back yard. We have no idea where the seed for the tree came from as there are no silk oak trees in our general area. Lucky for us it grew in the middle of the yard in an area away from other trees-as it will probably reach 100ft in the next few years!

Neutral MotherNature4 On Jan 30, 2006, MotherNature4 from Bartow, FL (Zone 9a) wrote:

The report that this tree is hardy in 9a is questionable. They used to grow in Bartow until we had one of our occasional hard freezes, but not one survived that I'm aware of.

Neutral mikenpat3 On Mar 14, 2005, mikenpat3 from Anthem, AZ wrote:

Reciently had this plant placed in my back yard. think it is beautiful, however allot of the leaves and some of the branches fell off this week. Bark is still green and healthy but concerned that the tree may be dieing. Is this a normal seasonal shedding or should I be concerned?

Positive suzyrock On Jul 31, 2004, suzyrock from Houston, TX wrote:

I live in Houston, texas & have grown a silk oak from a so called house plant that was 3 feet tall in spring of 1991. It has been topped 3 times since by the power company, ( I did not know it would become a tree) It is now appx 25 feet tall & 20 feet wide. It has bloomed 6 years in a row..Last summer I collected some seeds & did not plant them until the end of october. I babied the seeds all through the winter months on an enclosed patio & would bring them in the house on really cold nights. I have 22 gallon pots of silk oaks now that are 2 feet tall. I have planted seeds this month & will plant more in august..The tree is so gorgeous & would be more so if it didn't keep getting mutilated.

Positive angelam On Apr 10, 2004, angelam from melbourne
Australia wrote:

This tree is quite rare in the wild. Its timber was valued because of its distinctive smooth texture. It is spectacular in flower, especially in numbers, for example, in an avenue. Nectar eating birds flock to it.

Positive judy3163 On Feb 12, 2004, judy3163 from Santa Maria, CA wrote:

I planted the seed of a silk oak some 5 - 7 years ago; at first in a pot, and then when the sapling was about 3 ft. tall, it was planted in the ground. Since then (3+ yrs.) the tree has grown to some 30 feet but has yet to bloom. In this area (central Calif. coast) the tree is very popular and is used as a street tree as well as in many yards.

Neutral Monocromatico On Oct 19, 2003, Monocromatico from Rio de Janeiro
Brazil (Zone 11) wrote:

An spectacular tree when blooming, for some reason it hardly survives the climate of Rio de Janeiro, being planted more to the south of Brazil, where the heat is more moderate and the winters are colder. Its commonly used as wind breaker.

Positive solecurrent On Jun 6, 2003, solecurrent wrote:

Grevillea robusta is the largest member of the Grevillea family. It is a native of eastern Australia where its common name is "Silky Oak". It attains a height of 40 metres (130 feet) in the tropics; in temperate regions it grows to about half that.

The tree is usually evergreen but may be deciduous in cold areas. The leaves are the size of an adult's spread hand, bipinnate, similar in construction to the fronds of a tree fern. I have read books that suggest the flowers are 10cm (4") long, but the trees around Adelaide, South Australia (Mediterranean climate) bear flowers 30cm (1ft) long on average.

These beautiful brilliant yellow-orange flowers bear prodigious amounts of nectar which may be collected by briskly shaking the flowers in a bucket. If you suck on the flower of any grevillea you get a tasty few drops of nectar. The seeds are dark brown and the size of a pea. The tree self-seeds readily in our area in the Adelaide Hills (1100 ft altitude near Adelaide.)

The roots are intrusive so the tree needs to be well away from sewage pipes. From my experience the roots are not particularly hard on foundations as long as the tree is 10m (33 ft) or more from them.

Regional...

This plant has been said to grow in the following regions:

Grenoble,
Anthem, Arizona
Phoenix, Arizona
Tucson, Arizona
Bostonia, California
Canoga Park, California
Chico, California
Lake San Marcos, California
Manhattan Beach, California
Menifee, California
Pleasant Hill, California
Redding, California
Sacramento, California
San Diego, California (3 reports)
San Juan Capistrano, California
Santa Maria, California
Windsor, California
Bartow, Florida
Cape Coral, Florida
Daytona Beach, Florida
Gainesville, Florida
Kissimmee, Florida
Ocala, Florida
Palm Bay, Florida
Sarasota, Florida
Venice, Florida
Zephyrhills, Florida
Kailua Kona, Hawaii
Kurtistown, Hawaii
Austin, Texas



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