Asterias collectores in Tokyo area pick-up plants in the end of Feb and cut roots, and repotting in Mar every year.
I do repotting asterias a similar way. I started cutting roots on 27th and completed 65 asterias this afternoon.
I have 1400 asterias except very small seedlings. Ideally I should repot all of them but I know it is difficult.
I strated roots cutting from seedlings, sown seeds in September 2004. I could not do repotting them last year.
Hanazono
Before pick-up, pots are 85 mm square

Picked up asterias
I cut tap-roots when they were 2 years old. You can not see the tap-root.

Washed asterias

Finished cutting roots
You can see rotted roots easily in here if it is existing.

Side view of asterias
My roots are a bit longer than Tokyo. I use top-dressing sand but they use weathered scoria only, no top-dressing.

After dryed, set asterias onto empty pots and wait until the end of August.
I will repot asterias in the end of August.

Thankyou for showing this method Hanazono i remember previously when you showed me this i have done this now with several other species aswell and i find it great to remove all dead old roots and then re-root.
I now do it also to some of my touchy succulents and am having far better growth and less losses to rot although some are set back initially while re-rooting.
I find it necessary to do after winter due to lack of water the roots tend to die off and when watering resumes this invites a level of rotting mater which could invite more rot.
Would this is also be a reason for cutting off the roots or is it just to remove the tap root and encourage the finer roots to grow therefore helping the plant to grow better or faster.
Is this also done with other cactus like Ariocarpus.

cactuscook

I cut tap root when seedlings are 2 years old.
When you cut tap root, fine roots come out and no roots rotting even if you feed a lot of water to encourage growing in hot summer.

The photo shows 6 yeras old seedlings with large amont of fine roots.
Pots were filled up by roots and no space for additional roots growing.
This means you also can not expect further growing of the plant.
I did cutting roots and one size up pot to allow further growing.

You should not cut tap root of Ariocarpus.
Recovering is very poor.

Hanazono

I have completed repotting of asterias. I have rearranged asterias location and now 2nd house is asterias only as shown in the pohto.
Hanazono

OMG!!!! you have the most amazing collection Hanazono and i cant wait until they are all flowering it will look awesome... it will be a beautiful hanazono?

Hanazono do you wear gloves to prevent infection of the roots? and also what do use to cut roots with , scissors? are they treated to sterilize them between plant cutting ? beautiful collection of asterias!

blowng
I wear gloves to protect my hands. You have to remove old soil from roots by hands during repotting.
I use a knife to cut roots, sterilize between plant cutting.

We normally keep various species in a house eg Noth and South American cactus together and difficult set the house condition as optimum.
Asterias likes very hot condition in summer. I will lift the house temperature to around 50 'C and have a look the result.
Hanazono

Hanazono
I am intrigued by this technique of removing roots. I would be interested in learning more about it. Do you know of a book or website that might describe it in some detail?
many thanks
charlie

Charlie
Japan kabuto-kyoukai has a website and showing some methods for root cutting.
I am a member of the group. Overseas people can join the group through the website but unfortunately the site is written in Japanes.
Cutting asterias roots is common practice in Japan.
Root cutting is started when seedlings are 2 years old. This is the key prosess of the method.
Japanese cut roots in Feb. but I cut in Aug.
They use weatherd scoria for rooting media but I use clay base cat litter.
You may loose some seedlings during this rooting.
When pot was filled up by roots, plant can not grow and followinng every year they cut roots. The method is same as I showed in the form.
Root cutting of 2 years old seedling is shown in my album.
You may have a look.
Hanazono
http://home-and-garden.webshots.com/album/576636905XpeZGy

Thanks for that Hanazono.

I was wondering before how much of the root mass was being removed. But I have looked at your photos closely and I can see what you've done.

I'm going to have to try this one. It would be an interesting thing to see how it worked with with different species. At first it struck me as a pretty drastic thing to do to them, but I suppose we expect many cacti to form roots from cuttings. Though I have no idea if Astros can be propagated in that way.

Just one more question. Would cutting the roots a second time when the plant is a few years older have a similar effect? That is encouraging it to form new fine roots which enable it to forced into faster growth.

Charlie
When you have a look the photo, washed roots of 6 years old asterias in htis post, there is no tap root but some roots are grown quite thick.
The thicker root is ptentially rotting when you feed a lot of water in hot summer.
I feed water every 2 weeks in summer to normal cactus but feed weekly to asterias cut roots.
They will grow quite quickly without rotting.

I cut tap root of myriostigma seedlings as same as asterias.

I do not cut tap root of Ariocarpus seedling because recovering is very slow and many times failed rooting.
I lift the tap root joint from soil (planting shallow) and feed lot of water in summer.
Ariocarpus seedling will grow reasnable speed by this way without root rotting.
The attached photo is kotschoubeyanus seedling.
Hanazono

Hanazono thanks for all the tips , I also want to ask would I make these cuts now in spring ? (I'm not sure if you are in Australia)... and should I give the Astrophytums water before making the cut ?

blowng
You can cut roots now, in August or early September.
I live in Adelaide and it is not differnt from your place.

Watering before cutting roots is not matter but it is easier to remove plant from pot when soil is a bit wet.

Hanazono

thanks Hanazono , i have some 2 yr old seedlings of asterias and myriostigma i will try this on...

Thanks again from me as well Hanazono. You are a mine of information.

I suppose it could be possible to cut the thicker roots that are forming on the 6 year old cutting.

Lifting the plant up to clear its taproot joint is a great idea. At the risk of stating the obvious I get the impression that thicker roots overall (eg taproots and other thick roots) are more prone to rot than thinner ones. So its a question of either keeping them dry (eg by lifting) or removing them entirely if one wants to push the plant into faster growth.

charlie