Topic: Acid soil for Proteas

[Jesse]

Hi all  :)

I have ordered some protea seeds from a catalogue, going to give it a bash germinating my own - Protea burchellii and Protea cynaroides, at 6p each I couldn't resist.



Trouble is I know they like acid and well draining soil. I have slightly acid soil but heavy clay which would be no good. So I'm going to grow them (that's if they germinate) in a pot.

Can anyone recommend a good potting soil for acid loving plants. The other thing is if in a pot will the acidity of the soil become weaker over time? If it does, what mulch or additive can I use to top up the acidity, I don't think the plant will appreciate re-potting.

[MagpieDi]

Hi Jess
Wow, that sounds a bargain!
EJ posted about her attempts at growing them from seed further down this thread. The info might help, or put you off !  ;D

[Jesse]

Thanks MagpieDi, I read through and am probably as confused as EJ now! The bit about them not liking fertilisers I shall take note of. I remember in SA they grew well in really poor, stony soil conditions provided there was good drainage and they also like cool air in the mornings, perhaps spray with a fine mist. And I also remember they like very acid soil, hence my question about suitable potting soils and "topping-up" additives to maintain acidity of soil.

EJ - if you are reading this, are your seedlings still alive and growing? What mix of soil did you use for germination?

[Mrs Ava]

Yup, they are still growing and they germinated in regular seed compost straight from the bag.  They are now in ericacious compost with some grit mixed just to keep them nice and free drained.  They are living in the greenhouse where they will receive the same amount of neglect as the rest of my plants  :o ;).  This is about my 4th attempt at growing them, can get them to germinate no probs, but after 3 or 4 true leaves they wither and die  :'(  Shall keep you posted on their progress, and you do the same with yours.  ;D

[aquilegia]

You shouldn't water acid lovers with tap water as the limescale is akaline. Use rainwater instead.

I have a pieris (also acid lover) in a pot which I give a mulch of ericacious soil every spring. I have heard of people using conifer trimmings to mulch them. I still have to try this.

[Jesse]

EJ - in my research I read somewhere that proteas don't like humidity so make sure the greenhouse doesn't get too humid.

Aqui - conifer trimmings, that would make sense, I also read of using pine tree chippings but I think conifer trimmings are more easily available. Or course!, yes rain water is slightly acid isn't it.

[john_miller]

The R.H.S. Encylopedia of Garden Plants suggests using magnesium sulphate (Epsom salts- MgSO₄) and urea (ammonium nitrate- NH₄NO₃- 48% N) bi-annually at half strength as fertilisers. The sulphate and the nitrate will both combine readily with any calcium that you may have introduced to form calcium sulphate and calcium nitrate respectively. Both compounds are highly water soluble and will be washed out by watering, taking the calcium with them. This will allow the soil cation exchange sites to be occupied by aluminium instead of calcium, a major factor in maintaining an acid soil.
Should you wish to fertilise further you may want to use a product such as Miracid. This is formulated to allow balanced availability of micronutrients to calcifuges, those plants adapted to acid soils.