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Australian Native Plants

grevillea long john looking yellow

12 years ago

Can someone tell me what's wrong with my grevillea long john? I planted it last summer and it has almost doubled in size (about 6 ft tall) and has two flowers on it right now as we've had a very warm, dry winter. The problem is that the leaves are very yellow, except for at the very top, and dropping off on the lower branches of the plant. It gets about 2 gallons of water once a week on a drip system. I'm worried because I've lost a Banksia, a Protea 'pink ice' and a Leucodendron in that same spot of the garden. They all seemed to suddenly turn yellow and die after growing very well for 4-6 months.
My garden soil seems a bit inconsistent in different areas. This area seems more sandy than others so could it be simply a lack of water or could there be something deep in the soil that is killing these plants once the roots get deep enough?

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Comments (5)

funnelweb
12 years ago
Yeah not looking too good Pal, Aussie natives, and I reckon even South Africans, (leucadendrons) can be difficult outside of their native habitat. Having said that both of those like similar conditions; neutral to slightly acidic soil, excellent drainage, and they hate root disturbance. In fact you can easily over care for them - both are very tolerant of dry conditions. Many also are not happy in humid conditions. Lime, by the way, will yellow the leaves and eventually kill them so I reckon the first thing Id do is check the ph. in the soil. Oh, and if you feed them use only fertilisers suitable for Aussie natives, and use it sparingly.
Other than that good luck with 'em

B.
tropicbreezent
12 years ago
The main thing with fertilisers for these is that it must be very low in phosphorus.
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scorpionleather
12 years ago
Same thing happened with my Grevillea Superb. I talked to my neighbor who is a plant expert volunteer at the university arboretum. She gave me some Iron Chelate 10% powder. I gave it some of this Iron Chelate mixed in a water pail, and sure enough within a couple weeks the leaves turned nice and green! No more yellow leaves. I am using "Grow More Organic Based Iron Chelate" which is available at Amazon.com. It made a huge difference.
lenno
12 years ago
2 gallons of water a week is a bit more than it needs to. Try cutting back to a gallon per week. The iron chelate idea is great but a weak mix of sulphate of potash will help as well.
Avoid pouring over foilage, pour into soil around root ball, a teaspoon in 2 litres of water, stir well.
design100
11 years ago
I planted mine last October in the Sacramento area in clay soil, late afternoon shade, and with some supplemental irrigation. In April it's blooming very well - a hummingbird has claimed it. If other plants in the same area have failed in the past, recommend the scientific approach - test the soil for PH and fertility, find out what the plant needs, then replant in better conditions.

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