Advice on (re)rooting Eriosyce senilis

[ohugal]

Hi Everyone,

Last weekend I purchased some cacti from a grower while on holiday at the (Belgian) coast. He is retiring and selling off his stock. The plants were cheap, but the downside being that a lot of them are not in a good condition. I knew that when I bought them. The plants were potted in a mix of garden soil, pumice and grit. All in all not bad, but not as draining and porous as I would like it be. I'm not sure what to do with this E. senilis. It's lost most of it's fine roots and the main root doesn't look to great either. The weather at the moment is damp, cloudy and rainy with temperatures between 20-23°C during the day and 14-16°C at night. It will continue to be like this for at least 2 weeks. My hopes to get this plant growing again before fall kicks in are small. What do you fellow growers advise?

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[jerrytheplater]

Do you see soft areas on the main root? If so, cut out. If not, let the plant dry a week and repot in well draining mix and wait for rooting, even till next spring. What else can you do?

[ohugal]

Do you see soft areas on the main root? If so, cut out. If not, let the plant dry a week and repot in well draining mix and wait for rooting, even till next spring. What else can you do?

Hey Jerry,
How are you? No soft areas on the main root. I wondered whether I should trim it. The branching roots are basically torn off. I think I'm going to have to wait until next spring. Apart from the roots it's in good condition.

[Steve Johnson]

Hi Oscar,

I have a lot of experience with E. senilis and pretty good experience regrowing roots on cacti that are similar to your situation. Unfortunately I don't have enough time to go through everything now, but this will get you started:

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Measure lines A and B, then give me the measurements. From there, I'll be able to calculate the correct diameter and depth of the pot so you'll know what to look for. There is some "wiggle room" in case the pot you have (or get) is a little bigger. What you'll want to avoid is a pot that's obviously too big for the stem and roots. I'll guide you further over the weekend.

[ohugal]

Hi Steve,

A=2,5cm, B=3,5cm

I have a variety of plastic pots, so I'll make sure I don't overpot the plant.
Do you think I should prune the main root or is that asking for trouble? The growing season really started off great, but it has come to a halt with the 'bad' weather. The only ones cheering are the snails.

[Steve Johnson]

Hi Steve,

A=2,5cm, B=3,5cm

I have a variety of plastic pots, so I'll make sure I don't overpot the plant.
Do you think I should prune the main root or is that asking for trouble? The growing season really started off great, but it has come to a halt with the 'bad' weather. The only ones cheering are the snails.

Hi Oscar,

6 cm. width and 6 cm. depth should be fine. You can even go with 7 cm. depth to make room for a thick layer of gravel top dressing above the soil line, which I recommend. I'd leave the main root alone and let it grow new branching roots. More info to follow this weekend.

[Steve Johnson]

I have 2 Eriosyce senilis growing incredibly well with a 50% soil-50% pumice mix, so that's what I'll recommend. If you can't find pumice, you have a couple of options:

• Expanded clay granules. You can find them in the 4 mm-8 mm size range on Amazon Germany here:
  
  https://www.amazon.de/dp/B07HMXYQGT/ref ... 9kZXRhaWwy

• Perlite -- also available on Amazon Germany:
  
  https://www.amazon.de/-/en/Kalapanta-Pe ... Q5VR&psc=1
  
  Only problem with Perlite is that it floats. If you add a nice, thick layer of gravel top dressing to the pot, it'll keep the floaty stuff down so it doesn't get all over the plant whenever you water.

The soil in your mix should contain minimal organic materials (no peat!). Just to give you an example of what to look for -- this is "custom" cactus soil I got from the California Cactus Center in June 2011:

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The organic materials are chipped/shredded tree bark and maybe a bit of tree roots, but not bad in proportion to the actual soil. All I had to do was pick out the bigger chunks of tree bark before I mixed the CCC's soil with pumice. Something I didn't think about then I would do now -- use a piece of fiberglass window screen to sift out the soil and finer tree bark bits. That goes into the mix, and the bigger stuff left behind on the screen gets thrown away.

When I mixed the pumice and soil while the soil was dry, I noticed that the soil wanted settle down at the bottom of my mixing container. This is not good because you'll end up with compacted soil at the bottom of the pot after repeated waterings. To avoid that problem, an expert succulent grower taught me this handy little trick:

• Right before you repot, mist the mix with water just enough to let the soil and mineral components "hang together" for consistency. After the repot, the mix will dry out quickly, so you won't have a problem there. It will maintain its consistency with repeated waterings.

"Rule of thumb" for repotting -- let the roots settle in for 2 weeks before watering. However, your E. senilis needs to grow a new root system, and deep watering will be out of the question until next year. The only thing you can do is give the plant a sip every 2 weeks until your summer ends, then keep it dry in fall and winter. You may even want to just mist from the top so the stem gets some hydration. When your E. senilis starts growing new roots in earnest next spring, gradually increase the amount of water from sips to half-watering to soaks every 2 weeks. Going by the way I approach re-rooting cacti, IMO your plant should be ready for soaks next summer. The trick here is -- be patient.

[ohugal]

Hey Steve,

I have pumice.
Regarding the soil, what's the screening size? 1x1mm? 2x2mm? I have a sieve made up of window screening material and I use it to sieve out the fine particles from my soil mixes. As I understand it the organic component is mostly bark. Will pine bark do? It's something I have in stock.
I agree I will have to be very carefull with watering and I'm not planning on doing so until I observe new root growth. Is it an idea to pot it up in a 60% pumice and 40% grit mix until next spring? Just to be on the safe side?
I suppose I will put the plant in a warm spot with bright indirect light until it grows new roots.

[Steve Johnson]

Hi Oscar,

Here are the answers:

Regarding the soil, what's the screening size? 1x1mm? 2x2mm?

2x2 mm should be good. Like I said, the soil and finer organic particles go into your mix, what you have sitting on the sieve goes into the trash.

As I understand it the organic component is mostly bark. Will pine bark do?

I believe the organic stuff in my CCC soil is pine bark, so you should be good there too. When you said "mostly", that concerns me a little bit. Do you know what the other organic materials are? If you don't, organics of unknown origin could be a problem.

Is it an idea to pot it up in a 60% pumice and 40% grit mix until next spring? Just to be on the safe side?

Pumice and granite gravel (grit) are an either/or proposition -- use either one or the other. If you have pumice, there's no need for adding grit to your mix. Keep it simple with a 50% pumice and 50% soil mix. If you repot the E. senilis in that mix now, it may not do a whole lot in terms of growing new roots. But since you still have about 6 or 7 weeks of summer left, the plant may end the summer with the start of a new root system. Unfortunately you won't know for sure unless you unpot the plant, but doing it will be counterproductive. Once again, be patient.

I suppose I will put the plant in a warm spot with bright indirect light until it grows new roots.

Correct. Assuming that you repot the E. senilis tomorrow, you can give the stem a light misting 2 weeks later. If you do it at night while the plant's stomata are open, this will hydrate its skin more than it would if you mist during the day. The more that I think about it, I believe misting every 2 weeks until the end of summer is better than attempting sips which could accidentally turn into soaks. Set your spray bottle to "mist", pull the trigger 5 or 6 times, and you won't be overdoing it. Save the sips, half-watering, and soaks for next year.

[ohugal]

Hey Steve,

I said mostly because you also mentioned tree roots as part of the organic component. I was double checking whether just pine bark would be fine. Since pine bark drains quite well, I will pot it up in the 50% soil and 50% pumice mix. I proposed the mineral mix, because I wasn't entirely sure what the organic component was and what you meant by soil. That's clear now.
Some of the plants I bought had root mealies, so I had to unpot them and get rid of the soil. I soaked all of the plants in a pyrethrine contact insectide and will repeat the process in a few days to be sure. Then I will wait a few days before I put them in fresh soil. I have a ventilator to speed up the drying process.
I agree misting the plant is a better idea than watering and I will do so when the weather is sunny. Currently it's cloudy, rainy and humid. Thanks for the advice and fingers crossed!

[Steve Johnson]

Thanks for the advice and fingers crossed!

Any time, my friend!