Trichocereus Pachanoi Seedling Slow Growth

[Ishmael Fleishman]

Last winter I got hold of some Trichocereus Pachanoi seeds from NZ and some from Peru. I used takeaway tech combined with a heating mat and an LED light. I had a high germination rate. My substrate was not ideal I think - it was 50/50 organic/inorganic. Too many coarse 4 - 6mm stones.

 

I have not had any diseases I did, however, have an accident when the stand I used collapsed and the seedlings spilled on the floor and I had to pick them up and replant them. 25% died most survived. I now have about 50 seedlings.

 

At one point early in their growth they had too much light from LED and they turned red and purple. I took away the artificial light and they all eventually turned green again.
I have been watering about once a week - sometimes twice if we have a heat wave. Using rainwater
a weak solution of Seasol Yates liquid Iron Chelate and Yates Anti Rot Fungicide (Phosphonic acid). I have been using a pump spray and misting the seedlings.

I have had a few just wither and die but they have done well for the most part.

 

It has now been 6 months and the seedlings are around 12mm long and 5 - 7mm in diameter. However, some are more stout say 6mm.

Having never grown Trichocereus from seed. Is this level of growth normal or is the growth retarded?

 

I was hoping to re-pot them maybe putting them into a more organic substrate. 75% sifted cactus soil and 25% pumice. Maybe they would grow better?

 

I am also worried that the roots will not have enough depth in the shallow takeaway containers.

 

Should I re-pot them? Or should I leave them until next spring when they will have their next growth spurt?

 

Currently, they are outside undercover with a good mix of shade and light. However, with winter coming should I move them back inside where the temperature stays above 10c at night?

Edited February 6, 2023 by Ishmael Fleishman

[fyzygy]

Everything's growing too slow for my liking at the moment. Probably something to do with my age, or other subjective factors. 

I've had mixed results with takeaway tek method. If the media is properly wetted (not saturated) to begin with, there's seldom any need to intervene. Occasional ventilation probably doesn't hurt. I've never added anything other than moisture when (seldom) needed. And mine are always grown with natural light, no heat mat. 

From one container I carefully withdrew about a dozen or so to transplant into small pots. They've hardly grown at all, and the remainder now remind me of bleached coral. Probably should've just let them be, for a little longer. Even opening the lid of some takeaway containers can be a violent upheaval.

In future, I wouldn't sow so many seeds at one time. It's tricky juggling hundreds of tiny cactuses. Maybe that's another advantage of the coke bottle tek -- smaller surface area. That said, my attrition rate is pretty high. Occasionally I end up with only 1 or 2 or even 0 from a batch of seed. Or at the other extreme, 50 or more that I have to find homes for. Different varieties do seem to respond differently to environmental conditions.

Patience is a virtue, especially when it comes to plants. I would say your growth rates are normal. Tricho seeds can germinate quickly, but the first year is pretty slow. Sometimes the first 2 years. But others here have more experience, I'm no expert. I'd be interested to hear what a few of the resident gurus have to say. 

I've got some that are no bigger than yours, and they're probably 12-18 months' old.

 

[modern grower]

Trichocereus can handle near constant moisture but watering once a week is enough... I personally do not reduce light even if they become very dark as the new growth will grow accustomed to it. I do not keep in high humidity for more than 2 months and bright sunlight (full auz sun might be too much) from there forward. Keep moist and water heavily each week.

 

MY soil mix is 50/50 clay/granite(gravel) You can repot and any moment and as long as you are not too rough they can take a watering the following week. I repotted mine at 2-3 months they survived a month long drought in full summer sun at 4 months due to a trip. Remember to fertilize if you want but don't overdo it. A drought period is important doesn't need to be a full winter I usually do a month in spring and another in the summer and water all winter.

 

here they are at 6 months.

 

[modern grower]

Here they are at 1 year. After the slow down from intense sunlight they will gave a growth rate increase.

 

 

[fyzygy]

16 minutes ago, modern grower said:

here they are at 6 months.

Via takeaway tek?

[modern grower]

1 hour ago, fyzygy said:

Via takeaway tek?

no I remove mine from high humidity after 2 months keep soil moist. they suffered a month long drought last summer due to a trip but survived. They were very skinny and dark. I don't reduce light when they get red or purple/brown. Keep them there and just week them moist and fertilize lightly if you want (I didn't) after a month or so they will grow just fine and quite fast.

50/50 granite chips(gravel) and clay based garden soil. I did have some losses but will end up with more than I know what to do with them. sowed 50 seeds total I think I have 20 now?

[Ishmael Fleishman]

modern grower yours are like three times the size of mine at six months old.

I see you are in Brazil your weather is probably more consistently hot than mine.

My weather can get to zero.

I think I will re-pot them today.

[Ishmael Fleishman]

Ok - I replanted most of the trichocereus into new terracotta pots.

 

I think part of my problem was that my old substrate was just too much rock, and not enough organic. Or maybe the organics sunk to the bottom of the pot between the coarse stones.

 

My new mix was 25% peat moss, 25% worm casting, 25% pumice, and 25% zeolite.

 

I will wait a week and start watering. In the new containers, I can now bottom water, which will be good.

 

[modern grower]

I live in southern brasil so we have temps as low as -2C for a couple of hours during winter. Summers in my region reach 35C MAX but rocks heat up and surpass 50C.

 

From what I've observed is you just need to make sure the soil is aerated. The main downside of too much inorganic material is it drys out too quickly... I think 50/50 is a good compromise but depends on your local climate.

[Ishmael Fleishman]

I honestly think that my - old substrate was too coarse and dried out too fast.

 

My new mix is 50/50 and the inorganic is much finer pumice.

 

It has been two days and the little cacti are looking good, no limp or dying cacti.

 

QUESTION - why is it recommended that we, do not water a cactus after replanting for at least 4 days to 1 week? I read things like the shock of watering after transplanting. It just goes against the standard gardening advice with the most plant to water well after transplanting so that the soil settles around the roots and air pockets around the root get removed etc.

Edited February 8, 2023 by Ishmael Fleishman

[modern grower]

I water the day after repotting IF it didn't damage the roots excessively. Root damage may increase changes of rot with cacti. Some people go extreme and wait weeks to rewater but a couple of days is enough if the potting mix was bone dry.

[fyzygy]

I only withhold water from cactus cuttings that are yet to develop roots -- usually for several weeks (or however long it takes for roots to form). I water in repotted seedlings as a means of tidying up the mess I've invariably made. I've never suffered any losses that way, but that's not to say I haven't impeded their growth by doing so. On the other hand, I can better orientate a seedling with respect to gravity with the help of a jet of water from my misting bottle. I'll spare you the details of some of my more brutal repotting techniques. Let's just say I like to push the envelope when testing for plant hardiness. Not all plants, just the tough varieties. 

[Ishmael Fleishman]

I was very careful with the roots and so I have started watering again - Thanks for the advice.