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andros88

Acacia acuminata seedlings stalling

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Hi everyone,

 

I planted 30 Acacia acuminata seeds in November 2018 and most died off except these two (see pics). They've been this size (2-3cm) for 3 months and don't seem to want to push forward & grow. I live in Sydney and these grow outside in my courtyard with very lightly (10%) filtered morning and a bit of noon sun. My questions are:

 

1. What soil should I use? [Scotts Osmocote® Professional Native Potting & Planting Mix?]

2. Watering requirements?

3. Sunlight/temperature/humidity requirements?

4. Pot requirements?

5. Something else I should be doing to help these babies push past this stage?

 

Any help is greatly appreciated as I am struggling immensely to get any type of acuminata to grow and am worried about the potential mass deaths of seedlings in the future! :(

 

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Those seedlings are quite etiolated. You are best off killing them and starting over.

 

I can't comment on Sydney climate but here goes..


I use a product called Baileys Premium Potting Mix. Unsure if it's available in eastern states stores but any pre-made potting mix that is well draining w/ slow release ferts should be fine. Better yet, sieve out the big bits of bark. I don't bother with this anymore but I do recommend it still.

 

Give them HWT for 12-16 hours and then sow, keep moist and warm. I prefer to sow a seed into each individual pot instead of pricking out seedlings to move into individual pots. I place my acuminata tube trays in FULL morning (Perth) sun with dappled afternoon shade and they grow perfectly before planting out around March/April depending on size. I keep the soil moist but not drenched, even immediately after germination. 

 

Stick with a basic round plastic pot with drainage holes. I could recommend forestry tubes w/ root training ribs but probably no point until you can get the hang of growing them first.

 

I've given this exact same advice to numerous people on facebook and they've all come back to say the quality of their jam seedlings is much better.

 

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Just 20 of the many thousands I've grown. Sown early Jan. Probably plant them on my median strip after my next work trip. Jan 2018 I germed some of my seed and planted one out the back in late March, it is now just over 2m. They are not slow by any means.

 

If you have any friends in Perth who can pick up and post seedlings for you, you're welcome to a bunch of these for free. Probably the last season I'll grow them

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Posted (edited)

Thanks so much for your advice Gimli, it’s a relief to get some guidance. 

 

I suspect mine aren’t getting enough sun. I originally sprouted them indoors, then moved them outside. Do you place your seed trays in direct morning sun immediately after sowing?

 

Also, I am a bit confused about whether acuminatas require soil with low phosphorus. I was going to use native potting mix for this reason. Should I grow the seedlings in normal potting mix then transplant them to a native potting mix when they are larger? Or could I just sow them in native mix directly? Is your backyard soil low in phosphorus?

I tried to find the NPK ratio of the baileys potting mix with no luck... I wonder if it’s low phosphorus?

 

Unfortunately can’t plant them in the ground due to the constraints of my courtyard :(

 

Many thanks for your help!! It is much appreciated!!

Edited by andros88

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5 minutes ago, andros88 said:

I suspect mine aren’t getting enough sun. I originally sprouted them indoors, then moved them outside. Do you place your seed trays in direct morning sun immediately after sowing?

 

Also, I am a bit confused about whether acuminatas require soil with low phosphorus. I was going to use native potting mix for this reason. Should I grow the seedlings in normal potting mix then transplant them to a native potting mix when they are larger? Or could I just sow them in native mix directly? Is your backyard soil low in phosphorus?

I tried to find the NPK ratio of the baileys potting mix with no luck... I wonder if it’s low phosphorus?

 

Unfortunately can’t plant them in the ground due to the constraints of my courtyard :(

 

Many thanks for your help!! It is much appreciated!!

 

Once sown, they go into the sun conditions I mentioned above.
 

Acuminata (and many wattles) struggle to grow properly in pots unless the pot is in the hundreds of litres. You are best to grow them in the ground, if not at home then elsewhere otherwise not at all.

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12 hours ago, Gimli said:

Once sown, they go into the sun conditions I mentioned above.

Ah gotcha - I suspect this is what I was missing. Thanks heaps Gimli :)

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Thought I would update this thread with a little experiment I did where I varied the soil type for seed raising.

As shown in the attached photo, a variety of seeds were planted (A acuminata broad, narrow & burkittii) at different times in three different soil types:

1. Native mix (low phosphorus)

2. Native + normal potting soil, Native + cactus mix (mid phosphorus)

3. All cactus mix (highest phosphorus)

 

Even though I didn't control vital parameters (time of planting, seed type or even the number of seeds in each soil batch etc - although I took care to distribute seeds between soil types at time of planting) its clear that the members of the native mix performed better than their counterparts, growing greener, larger and faster. Members of the native+cactus+potting showed more yellowing + stunted growth (and greater susceptibility to powdery mildew). The single member of the cactus mix has dried up and died.

 

As an aside, any recommendations on how to combat powdery mildew on A acuminata seedlings?

 

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Eco neem, or potassium bicarbonate works a treat on pm

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Oh awesome - will give eco neem or potassium bicarb a try. Thanks for your (continued) advice Glaukus!

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You can buy potassium bicarbonate sold as "eco fungicide" at Bunnings. 

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