problems with Grevillea

18 years ago

I don't know what I am doing wrong. I planted a Grevillea olivacea in april ...late spring here...and its curling up its toes. I have mulched it and put on bark chippings, we had alot of deep rain unusually at the beginning of June and since then no rain. But its watered daily on a drip and by hose. We are on a rocky coast alkaline soil which is clayey. I planted a Westringia fruticosa at the same time and that is looking great. I planted a G. robusta 2 years ago and that is fine although no flowers yet. I also planted

Grevillea johnsonii

Grevillea rosmarinifolia ÂRosy PosyÂ

Grevillea x Robyn Gordon and none of of them are doing that well.. please help as I adore grevilleas, as an expat Kiwi I love a bit of down under

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Comments (6)

lillypilly
18 years ago
Your problem is your soil, most grevilleas detest poor drainage (ie clay soils) and prefer slightly acid soils. Westringias seem to grow in anything. I dont know what you are going to do as your options are limited. You may be able to dig them up and pot them if they are not too large yet (they may not live) and raise your garden beds, adding sulphur, pine needle mulch...anything that will acidify your soil (only short term, you will have to repeat this each year). Or keep them in large tubs?
Note: grevilleas also hate fertilizers with phosphorous and if unsure only fertilze aus natives with blood and bone - or nothing at all - increases the flower show.
A far better bet would be callistemon in your soil conditions.
Sorry to put a damper on things for you. I love grevilleas too!!
trish_g
18 years ago
Grevillea olivacea does well west of Toowoomba, where the soil pH is 7 or more, which has made me wonder whether it's a bit of an exception to the "prefer acid soils" rule. Does anyone else know this? I'd like to know what the pH was, before recommending adding sulphur and acidifying mulch. A healthy G. robusta would seem to be an indicator that it's acid enough.
It may be hating the daily watering regime, too. And if you've fertilised, the Grevilleas may be a lost cause, as it's hard to remove phosphorus once it's been added. (G. robusta is phosphorus tolerant, however.)
But as lillypilly says, the most likely cause is the clay soil. Raised beds with imported sandy soil might give you more success.
But is it worth it? Growing plants to suit the soil can be altogether more rewarding than trying to modify the soil to suit the plants.
Best of luck
Trish.
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Grevillea victoriae is likely the species referred to. It is arguably the hardiest for this area and I know of several NW GW members that grow this plant (Ian, chime in please!) and have for a number of years. I just recently (September) acquired one, still in a container. I moved it indoors into a protected location well before our recent bout of cold weather but it is looking definitely peaked at the moment :-) I am fearful but hope for the best. Mercer Island, because it is surrounded by the temperature moderating effect of water, should offer a pretty suitable environment - Colvos Creek Nursery on Vashon (similar situation) has been growing and offering this plant for years. I'd still look for a somewhat protected location with reflected heat, especially if full winter blooming is desired. FWIW, there are other winter flowering plants that will attract hummers and perhaps be easier - certainly hardier - than Grevillea to grow. My Mahonia 'Charity' is in full bloom right now and visited often by hummers. Soon, witch hazels and winter blooming honeysuckles will add to the offerings. Here is a link that might be useful: Grevilleas for the PNW
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You're having a bad time, aren't you Penny? Have you been fertilising? If you have been, stop it at once! As Mallee points out in reply to your banksia question, fertiliser can be poisonous to some natives, expecially those in the Proteaceae family, which include banksias, grevilleas and waratahs. Some people fertilise those plants with a special native fertiliser, which, if sparingly used, can hurry up young plants a bit. However there's no real need to fertilise native plants at all. If you have fertilised your potted grevillea it may be possible to flush some of the excess phosphorus out of the soil by lifting the pot so the water can run out the bottom easily, and then watering generously. Mallee's other point about poor quality water is another good one. Have you been using water polluted with detergent? If you are in a position to use rainwater only on your Proteaceae it's a good idea. Can you use bore or townwater where you are? If you are restricted to greywater, you could try keeping a jug beside the sink where you put the detergent-free water (such as the rinse-water from the teapot). Trish
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could it be that black sooty mould? if so that is commonly caused by scale insect and/or mealy bugs, and they are commonly bought to the plant by ants. mealy bugs easy spot they are little whitish furry bugs around near the growing tip, scale look like hard little pimply lumps also around near the growing tip. if it is the above you need to control the ants first then make a white oil solution (homemade is easy) and spray the infected area with that after the heat of the sun. it has been very dry of late that is when ants become more prevelant, also with your callistemon problem because of the dry (low humidity) could it be spider mite? if so they are easy to control just introduce some mist watering around the foliage area to increase humidity keeping a bucket of water under each plant will also help the humidity. in both cases if the problem is too bad a prune up to remove all infected tip end wouldn't be out of the question, just be sure to destroy the prunings don't compost them or hold them on site. len Here is a link that might be useful: len's garden page
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I doubt very much that pH is the cause of your problem. If as you say, the plant is showing normal growth then pH would seem to be fine. If you have a pH (iron deficiency) problem then the typical evidence would be stunted growth and pale yellowing on the leaves especially the new growth. How old is the plant? It could be that there is an excess of Nitrogen in the soil. If the plant is only a few years old then time will result in flowers. The plant will eventually exhaust the soil of those growth nutrients like Nitrogen, as long as you do not feed it for a while (until it flowers). Some Potassium can encourage flowering. Back off on the watering as well.
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jholm11
17 years ago
I too am having troubles with getting a Grevillea Robusta to flower, as well as a Giant Bird of Paradise.
I live in Perth, a mile from the coast near Fremantle, the soil has a lot of limestone, well drained, mulched, and I have been feeding them NPK, Osmocoate, sheep manure, seaweed. Lots of green growth but no flowers.
funnelweb
17 years ago
They don't like lime! Eremophila coccinea (from WA, south of Perth) grows in sandy soil over limestone, but I tried dolomite under sandy soil and mine failed - just died. My second one, just planted, waterd in a few times to settle, and then left alone to live or die (in the eastern states) in well drained red volcanic soil has lived now 4 years and flowers each year. No lime at all!
funnelweb
17 years ago
No, no, not eremophila, Banksia coccinea.
QldGardenFan
13 years ago
I have a very healthy Grevillea Robusta which was about 4 feet tall when transplanted in 2002. Now it is about 60 feet tall. No special treatment at all. Our soil is very rich in sandstone, the rocky variety and we have heaps of rain and it is on a well drained slope.
Photo taken yesterday, springtime here in Southern Queensland, Australia.

problems with Grevillea

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lillypilly

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