Rooibos

Has anyone tried cultivating Rooibos? (Aspalathus linearis)

I haven't really found any info on the net about cultivating this plant outside of south Africa, besides a couple sources suggesting attempts have been unsuccessfull in similar climates. The sources don't back this statement up with any evidence though?

Does anyone have evidence to the contrary?

I live in a climate very similar to the western cape, and am going to try growing this.

Any recommendations, input, etc?

Not direct evidence to the contrary, but I was amused to read one page that talked about how difficult it was to grow them:

"Pouring boiling water over Aspalathus linearis seeds and letting them soak over night before planting them helps promote growth."

Not sure if they are serotinous like some species of pine, but it seems like a boiling water soak is a good way to kill most seeds.

The seeds are really hard to get. They are tiny tiny tiny seeds and scattered to the wind within hours of maturation.

That's not true. There are several seeds which need the boiling water treatment.
I forgot this when I tried to raise tagasaste and failed. Some seeds even need fire.
If you want rare seeds try at horizon.

that's Horizon Herbs, I believe.  I don't think they've got rooibos seeds, but they've got honeybush (Cyclopia subternata, which is similar.

Hah, I already have seeds. Seeds need to be scarified before planting, I originally posted to ask about cultural requirements regarding the cultivation of the species. For some reason I'm concerned about soil being different. Every source I've encountered says it grows in sandy, acid soils. We don't have many of those here (if any!).

Here is some info from a good seed source:

"Aspalathus linearis seeds will usually germinate in 14 days, even under good conditions germination may be erratic. Sow seeds about 2mm deep in a Sandy peat seed sowing mix at about 20°C.

Smoke. Scarification. Acid treatment."

So, I guess I'll put them in the charcoal grill, then nick them with a pair of nailcutter depending on how big they are, then soak them for a couple hours in diluted H2O2, then plant in an acidic mix.

Since I have ~100 I'll try some control groups to see the best germination formula.

The acid soil would be the major limiting factor in adapting this species as a viable economic asset to Mediterranean climates.

ediblecities wrote:
That's not true. There are several seeds which need the boiling water treatment.
I forgot this when I tried to raise tagasaste and failed. Some seeds even need fire.
If you want rare seeds try at horizon.

Yes, as I said in my post, there are serotinous species (including many pines) that need fire to open the cone, and/or to change the seed coat to allow water in. But if the temperature of the embryo plant within the seed is raised anywhere close to boiling (much less 700 degrees F of a fire), that is going to kill the seed.

In this US Forest Service page that advocates the use of boiling water to help break seed-coat dormancy, they warn that "Hot water can kill the seed - it is important not to soak the seed for too long!"  The smaller the seed, the larger the volume of the water, or the longer the time, the greater the chance that the plant inside the seed is exposed to deadly temperature. If the rooibos seeds are small and are soaked in a much larger volume of boiling water, or soaked for too long, they will not germinate - they will be killed. I suspect it is rather easy to overdo the boiling water treatment, especially when the people promoting it (as with my original post) are quite vague about it. I greatly prefer mechanical scarification, as there is usually lots of room for error; chemical scarification comes in second, and boiling water is third unless there is a proven protocol for a species. 

http://www.winrock.org/fnrm/factnet/FACTPUB/AIS_web/AIS12.html

After a few minutes the water cools anyway, so how is it possible to soak for "too long"?

I have tried various methods also. Scarification and then soaking in warm water until the seeds double in size is suppose to give the best chance of germination. I've bought 10 seeds and they're not that expensive. I've tried various soil types. Regular soil. Also a mix between the following: coarse desert sand, peat moss, cactus soil, vermiculite, and perlite. I have managed out of the first set of five to have two "germinate" (they are in the right place where I planted the seeds). The soil where the two germinated is mostly peat 40%, 30% cactus soil, and a mix between perlite and vermiculite and sand in similar proportions. The next set of 5 I am doing a more progessive mix 60% soil/peat and 40% sand/vermiculite/perlite. I have also innoculated a couple of seeds with rhizobia bacteria (as they are suppose to help the plant fix nitrogen) to see if they sprout/grow better. I have to wait to see these results.

I have no idea what sprouting rooibos looks like though. If anybody can give me a description as there are no pictures on the internet I will be greatly appreciated. In gratitude, if my next set of attempts are more successful, I will share pictures, tricks and tips, and so on. 

An interesting side-note is that in South Africa, the seeds are usually collected by digging up an ant hill.  It seems that the ants collect the seeds for winter forage, and often have large stashes of them.

Perhaps that was discovered when somebody poured boiling water down an ant hill to get rid of the ants, and found a nice rooibos patch there the following spring.

Two of the five that I planted sprouted. The innoculated one has bigger initial leaves and is putting up its first needle.