Acacia Phlebophylla germination method

[Groot]

Now that spring is almost upon us I thought I’d share the method I use to germinate Acacia Phlebophylla seeds. It has taken a few years of trial and error but now I have it down pat. I’ve got it to 90%+ germination rate all in the first month of spring. It certainly isn’t the only method but it works for me and I thought sharing might encourage others to give it a try.

 

I like to start the process early August (as it takes about 4 weeks for them to start germinating) to take full advantage of the spring/summer growing season.

 

I use a razor blade and take a tiny nick off the hilum end of the seed, this is where the root will come through. Be careful not to take too much off you only need to get through outer coat. Once they are all scarified I then soak them for 24hrs in previously boiled but COLD water. Boiling water at this point will kill your seeds if using this method. 
 

After 24hrs and seeds have swelled up, I now put them in a plastic Chinese container between two sheets of damp paper towel (I like viva brand as it holds a lot more moisture than cheaper towel), all spaced out so they aren’t touching. I put the lid on and place them in the fridge. 
 
They will germinate in the fridge and throw out a tap root but it normally takes about four to six weeks for the first ones to start.  Once they grow their little root (2 or 3mm, don’t let it get too long) I pick them out of the container and put the rest back in the fridge, checking them every few days. It normally takes a few weeks for them all to germinate once they’ve started.

 

I then very carefully with a pair of tweezers peel off the outer coating of the seed and plant them in a seedling tray just under the soil with the root facing down. I put the seedling tray in the hothouse watering daily as seedling trays dry out quickly. Your little seedlings will be up in a few days.

 
soil mix used is pretty simple, 3 parts Bunnings native potting mix to 1 part river sand, with a handful of soil from the base of one of your local acacias as a rhizobia inoculant mixed in to every seedling tray.

 

They take a couple of months to get their first adult leaves but once they do they grow fairly quickly. I also then start fertilising them with swift grow (swiftgrow.com.au) every couple of weeks.

 

Happy gardening 

 

Edited August 16, 2023 by Groot

[Strontium Dawg]

Nice work. I don't seem to have too many problems getting them to germinate, but keeping them alive past 3 months has been challenging here. Giving them another try soon.

[Groot]

Give that swiftgrow a go they really seem to thrive on it.

I still loose the odd one, even a couple of years old for no reason at all, that I can see anyway.

[fyzygy]

Q: If you're going to the trouble of using tweezers to vertically orient each sprout, why not plant them directly into growing tubes rather than seedling trays? 

 

I've never nicked the seed coats, always use just-boiled water to soak prior to cold stratification, never use tweezers, don't usually fertilise or add inoculant, and still have pretty good germination rates, 90% or better. I have much more trouble with A. courtii, here in Melbourne (the one Herbalistics, in Queensland, says is "easier in cultivation"). As soon as a few of mine have sprouted in the refrigerator (in moist sphagnum moss, in a ziplock bag) I scatter the whole batch into a prepared seedling tray and lightly cover with coarse sand. Most if not all find their own way, eventually. 

 

I guess I'm doing a "no fuss" version of the Herbalistics tek, but it's always good to learn of alternatives and enhancements. Groot's plants look a lot lusher than mine, and I'm used to using SwiftGrow too these days, on his recommendation. I have trees grown from seed that are several years old, container-grown. They are yet to flower, but show no signs of giving up the ghost just yet. (I killed an entire batch of seedlings one year, by going too hard, too soon, with fertiliser. The only one that survived was a straggler that was randomly spared my clumsy TLC.)

 

Granite chips could be a useful amendment, given the plant's native habitat. But I usually stick to the general formulae given in Marion Simmons' book Growing Acacias. I sprout legumes in my kitchen and often give the rinse-water (and occasional legume) to my acacias, although I'm not 100% sure it assists rhizobia colonisation (more of a hunch, if you will). 

[Groot]

The tweezers aren’t to orient the sprout they’re to remove the outer/hard coat of the seed. I was loosing a lot either not being able to shed the husk once they had sprouted or they would just not progress any further and on investigation found the seeds rotten inside the husk. Removing the husk fixed both of these problems.

when I’m planting them I just make a small hole in soil with a pencil and drop them in.

[Groot]

In my experience the husk on Phlebophylla seeds is a lot tougher than most other acacias.

[fyzygy]

First flowers emerging, from one of my potted specimens, around 3 years old. 

[Groot]

How cool, it’s always exciting when something flowers for the first time. None of mine are at that stage yet 

[Therefore2.0]

CSIRO developed a bradyrhizobium innoculant specifically for Acacia called Wattlegrow (made from 4 special selected strains) Apparently worked well with phlebs (think herbalistics mentions it)

 

Sadly not made anymore. 

Acacia not super fussy on what strain of bradyrhizobium they like. I bought some different strains to run some tests.

 

[fyzygy]

13 minutes ago, Therefore2.0 said:

Acacia not super fussy on what strain of bradyrhizobium they like. I bought some different strains to run some tests.

I reckon you could establish a compatible colony using plain old lentils. 

[Sib Mackern]

How do you guys care for seedlings once they've sprouted? I can get my acacia (acuminata) seeds to germinate easily enough but they almost always develop a couple sets of leaves then slowly die off. Often they grow leggy and thin then wilt before giving up.

I've tried a few soil mixes and at the moment am trying a blend of native mix soil, a little peat moss and some perlite for drainage. I have been germinating in seed trays with a peat/sand mix but i think germinating directly in a tube pot might be the go. 

I'm thinking maybe it's a lack of light, lack of air circulation, overwatering or all of the above. I put them on a windowsill inside once germinated so maybe the still, relatively humid air isn't good for them.

I'll have a read of the links fyzygy posted a bit later to see if they address this.

[fyzygy]

Google "Simmons" on this site for cultivation tips. Information from her book Growing Acacias. 

Leggy suggests they're looking for more sunlight. 

I don't know what "native soil mix" means, but it could be overcharged with nutrients. 

I tend to avoid peat moss for acacias. I wouldn't even bother trying without coarse river sand. 

I transplant them to tubes after they've germinated en masse, and developed true phyllodes. 

Mine start off life in a greenhouse, so I doubt that your indoor humidity is the problem. They do need to be gradually acclimatised to less humid conditions.

I have some acuminata (narrow phyllode) seedlings in grow tubes that are ready to go, if you get desperate. 

 

[Sib Mackern]

Poor wording on my part, it's a potting mix from bunnings: https://www.bunnings.com.au/scotts-osmocote-25l-native-premium-potting-mix_p2961492

Thanks for the info and i will definitely reach out for some tubestock if all else fails (although i'm likely to keep trying stubbornly until i'm successful )

[fyzygy]

The nutrients in that mix might be counter-productive for the purposes of germination. I had a batch of A. phlebophylla seedlings that I killed (wilting, shrivelling, and dying pretty much as you describe) because I accidentally fertilised them. 

Seeds in general, I reckon, are self-sufficient and have no need of additional nutrients. So I tend to avoid fertiliser at this stage, as a rule of thumb. 

For potting on, once established, native potting mix from Bunnings gives good results. 

Bunnings also sells coarse river sand for propagation, your best friend. 

 

Here's what Simmons recommends (scanned pages with info here)

 

 

Seed growing mix:

3 parts washed or sterilised coarse river sand

1 part peat moss or aged crushed pine bark

or

3 parts perlite

1 part peat moss

 

Potting on mix:

3 parts coarse river sand

1 part peat moss or old milled bark

1 part loam or perlite

or 

2 parts sand

1 part peat

1 part gravel with old manure or compost added

 

Cutting mixture:

3 parts coarse river sand

1 part peat moss or old crushed bark

1 part perlite

or a soil-less mix

3 parts perlite

1 part peat moss

 

[Therefore2.0]

On 9/4/2024 at 4:54 PM, fyzygy said:

I reckon you could establish a compatible colony using plain old lentils. 

That's what these strains are for ideally..... Pea, lentil, mung. 

 

$5 a pack. 

Edited April 10 by Therefore2.0
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