Growing acacia obtecta

[Micromegas]

Howdy, i recently sprouted a few dozen obtecta seeds. They boosted at first but now the seedlings are maybe 2 inches and very spindly and some are dropping leaves, others appear to be rotting and dying. They've grown some nice adult leaves but the stems are really weak. Most are still alive but i fear for their safety. Acuminata and obtusifolia in the same soil and situation are doing great.

Although the soil is good it does not drain as quickly as I had hoped especially in the tall tubes i am using but usually these are good for seedlings. I water once every 3 days roughly depending on the weather. Occasionally with seasonl. Interestingly, the obtecta grew really long roots really fast coming out the bottom of the tube within a week of sprouting.

Where I am living now has a really mild climate and the water is really hard/alkaline. But I'm about to move to place that is really hot and sunny with less alkaline water.

Anyone with any experience have any thoughts on what I might do to strengthen them up? The seed leaves lifted well above the soil when the radicle grew downward i wonder if i need to put more soil around the collar of the plant (i.e. the seeds were not planted deep enough?)

Cheers,

Micro

Edited January 31, 2010 by Micromegas

[tripsis]

How old are the seedlings?

[Micromegas]

Maybe 6 weeks.

[Micromegas]

well i talked to a local reveg guru todays with bucketloads of experience. Not with obtecta tho but all sorts of acacias. I described the issue and he was familiar with it, the yellowing of the leaves, dropping leaves and dying. He said this was common with arid zone acacias especially those with larger seeds. He said he had this problem especially a.oswaldii which is a prolific SA arid zone acacia where it looks great for a couple of months and then starts dying.

His theory was, first, that it may simply be a case of overwatering, but when i said i only water once every three days this didn't really fit. I had the tubes in a vegetable box which is closed at the bottom. He seggested moving them into a tube holder that has airflow which i had done the night before so the roots get air pruned (exposed to air and die) rather than sitting wet at the bottom of the vegetable box.

Second he said that often arid or semi-arid acacias are quite specific in their mychorrizal/rhizome selection and this may be why many are so difficult to grow as seedlings whereas other are non-selective and can just grab em floating from the air or in potting soil. He suggested maybe grabbing some soil from an area of similar ecology.

He also said the mild climate and alkaline water would not help a plant that likes it more neutral and hot. I'm moving to a place where it is arid and hot and the water is from the murray not a limstone underground basin so we'll see. Not that I am aware if obtecta is an arid zone plant. Geraldon nearby has annual rainfall of 450mm but inland would be less.

Anyway there you go if you're interested. Would like to hear if anyone else has tried this species with or without success. I'll keep my fingers crossed as most of em still seem ok-ish.

See ya,

Micro

[tripsis]

I have limited experience. I've got a few seedlings going, but only one is about 2 months or so old. I've got it is poor, sandy, gravelly soil with a bunch of other Acacia species. It's going well and would be around 10cm or so at the moment. It's stem is lignifying nicely and it has large healthy leaves. It's been pretty hot here, so that may be helping. I water once the soil is dry (or whenever I remember). I may have fertilised it once. Remember that native do not like soils high in nitrogen, so your ferilising may be affecting yours.

The other seedlings I have are probably only 2 weeks old and are in a slightly richer mix, but seem alright with it at present.

If they do need specific mycorrhizas, they won't be getting very far in the long run. It's been a concern of mine, but it's all trial and error I suppose.

[Birdwing]

The seed leaves lifted well above the soil when the radicle grew downward i wonder if i need to put more soil around the collar of the plant (i.e. the seeds were not planted deep enough?)

 

Probably wouldn't be advisable as you'd be encouraging collar rot especially on smaller seedlings.

[ferret]

i grew a few of these from seed about 2 years ago, kept one in melbourne and planted the rest at 6 months up in NW vic, the ones up there have since died , they were planted in harsher conditions to some acuminata and neurophylla on the same property which are now going strong and standing about a metre tall and the same wide.

the obtecta's did cop full sun for most of the day, whereas the acuminata and neurophylla had shade in the afternoon. all were not watered at all since planting and started in commercial native potting mix with a bit of extra coarse sand. the coarse sand i now feel is not essential as straight up native potting mix has more than enough drainage.

the one i kept in melbourne at a mates place was fine for about 1.5 years, nice 40cm plant branching a lot up top, then due to lack of water and probably kept in too small a pot passed on a few months ago.

i doubt they need specific mycorrhizae, give them nice root space and watered but never waterlogged and they should be fine. id say the problem your having is due to wet feet as youve indicated?

they really do pump as seedlings, last batch i planted about 1cm deep and had roots out the bottom of the forestry tubes before the cotyledons had even broke the surface!