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andros88

Acacia acuminata losing leaves, drying out

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Hi everyone,

 

Hope your new year is going well so far and all your plants are thriving in this warm & humid(ish) summer!

 

My Acacia acuminata (var small seed) seems to be struggling a lot - most of its leaves are drying out, turning orange/yellow and falling off. Just as the last few leaves fall out, it miraculously manages to produce one or two new green ones, before those end up drying out and falling off too. It doesn't seem to be able to retain any of its old leaves while simultaneously producing new ones. Any advice on what could be causing this & what I should do differently?

 

A bit of info on its growing condition:

1. Grown outdoors in full morning & a bit of arvo sun in Sydney, Aus.

2. Its in a laundry basket with lots of holes cut out (air pruning).

3. Soil medium is cactus/succulent mix with perlite. Compost on top.

4. Soil dries out pretty quickly but I replenish it with moisture every one or two days.

5. Using a range of fertilizers, normally Seasol & Powerfeed, and sometimes Maxigrow - every week(ish) during spring/summer.

6. Plant was purchased in mid-Nov (looked healthy when it arrived).

 

Any advice on how to grow this wonderful plant is much appreciated! Thank you :)

 

 

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I'd suggest maybe the actual mix is too rich and too many ferts. Natives like this have evolved to live in very poor souls. Accaias will tolerate nitrogen, but don't like a lot of phosphorus at all. I'd swap your soul mix for a native plant mix, with some gravel mixed in as a first step. Don't use the powerfeed or maxigrow at all. Seasol is fine, it's not a fertiliser as such. Most acacias don't require even any nitrogen to do well as they are legumes I they actually draw in nitrogen from the air and fix it into the soil via root nodules.

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Hi Glaukus - thanks for your advice.

 

I'm guessing the "Osmocote Professional Native Potting Mix" available from Bunnings would be suitable?

From the description of the mix on the Bunnings website: 

  • Formulated as an open, well drained mix that creates ideal conditions for drought tolerant and phosphorus sensitive plants.
  • Low phosphorus to prevent yellowing leaves and phosphorus toxicity

Phosphorus toxicity may very well be the issue. I had no idea!!

 

Will pick up some tomorrow & hold off on fertilizing. Thanks a bunch for your help :)

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Catch you tomorrow, we can chat more in person!

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Are my plants dead? Attached pics of acuminata (narrow phyllode) and burkittii spp. There is shockingly little info about acacias online.. will they recover?? :(:(:(

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Edited by andros88
Rotated photo
  • Sad 2

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At that size it probably won't shoot from the nodes. Bigger specimens will - had a 7ft one which I cut back to about 2-3" and it's shooting.

 

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A bog standard potting mix or native mix will be fine and cut back on the ferts. Don't even bother giving them Seasol.

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Thanks Gimli, I've washed the existing mix off the roots & transplanted them into native mix. When I took them out they had a strong(ish) root system - so hopefully they'll recover. Definitely won't fertilize. Hope my babies live!!!

 

There has to be a disclaimer with acuminatas like "extremely sensitive to phosphorus" in large bold letters somewhere online for us gardening noobs (wasn't aware of this until Glaukus pointed it out). I also have a maidenii, floribunda & obtusifolia that are doing fine in the normal mix.

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Doesn't look promising... 

 

If they were initially tubestock that is a brutal wetting/drying cycle for what the volume of media appears to be. 

 

I'm suspect on that container design for a few reasons, and also unglazed terracotta for acacias (from experience under cool temperate conditions) . 

 

If you manage recovery and still struggling, try putting a garbage bag/cover around the container for a bit, and adjust watering schedule as required.  If that improves change your containers. 

Edited by waterboy 2.0

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Thanks for your input waterboy - should I be using a tall plastic container instead?

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*heavily medicated/sleep deficit  :)*

 

Such an open container,  against brick will have moisture stripped out rapidly,setting up a large moisture gradient. There's also the chance the core of the media has had a wet patch with that watering frequency,probably directly under the plant with what I presume is the container depth. 

 

You can really see the drier ring on the first piccie above to sorta  get where I'm coming from . The open "face"  of the media is more than commercial root pruning containers by the looks of it. 

 

Stopping feeding them is the priority though:wink: . Keep it simple,dont push them. 

 

Id use a "standard" pot . Bigger the better, it'll never grow as well as In ground though as it's limited in many ways. 

 

You'd be better growing the plants up to size to use the basket container IMO (or garbo bag/wrap then uncover) ,but it would still be high maintenance I reckon. That don't mean I'm right:wink:

 

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Ah awesome - thanks for the advice waterboy! Appreciate it :):)

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Hmm this article "Phosphorus and Iron Nutrition in Australian Native Plants" suggests a foliar spray/soil drench of iron chelate to rectify phosphorus toxicity - anyone have any experience with this? http://anpsa.org.au/APOL1/mar96-2.html

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