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Illustro

Cacti Seed Sowing

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I am getting ready to start some seeds of about 40 different species and varieties from the Ariocarpus, Aztekium, Epithelantha, Lophophora, Mammilaria, Obregonia, Pelecyphora, and Turbinicarpus genera, I just have a few really quick questions for those seasoned seed raisers here.

The first is, could you please critique my seed raising plan?

Outline:

- 1/3 generic seed raising mix to 2/3 small-grain (1-3mm) pumice (sterilized in microwave)

- treat w/ copper-based fungicide (copper oxychloride)

- dense sowing (0.35cm^2 = 0.59x0.59cm soil area per seed), roughly equivalent to 100 seeds in 6x6cm pot

- 1-2mm thick pumice topping on seeds (none on Aztekiums due to their size)

- wash seeds into mix w/ sprayer (boiled rainwater)

- heated propagator w/ 18" grow fluoro (propagator shrouded w/ reflective foil casing)

- 16hr light @ ~24-28°C; 8hr dark @ ~5-10°C

- bottom water w/ dilute (~0.01%) low N fert. (Yates 'Thrive' cacti & succulent), beginning several weeks after germination occurs

- keep in propagator for 4-6mo. after which humidity is decreased gradually

Secondly, how much attention do these slow growing species need in the early stages?

I wish to know this as I will be away for 16 days during the end of June to start of July. Would you take the risk of starting the seeds now and being away from them for a couple weeks (when they are ~6 weeks old), or do you think it would be better to hold off until I get back?

Cheers! :)

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Sounds good to me, you should get heaps of little cacti seedlings.

I wouldn't worry so much about bottom watering when they're germinating though.

I like to open the lid to inspect what's going on and exchange the air, I usually give them a spray with water then.

Also you would've probably done it anyway but make sure you let the soil cool before putting the seed in.

Personally I like to be there in case they need watering, or drying out if they're too wet, fungal problems etc. but if you're treating with

fungicide you might not have any worries.

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Sound like an ambitious plan. Good luck and patience with the Aztekiums, you will need it!

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- 1/3 generic seed raising mix to 2/3 small-grain (1-3mm) pumice (sterilized in microwave)

I would not sterilize, in my experience this invited molds into niches that were occupied by beneficial microbes.

Rather i would employ commercial topsoil instead of the seed raising mix, and then use pumice or some other similar medium at the ratio you provide.

- treat w/ copper-based fungicide (copper oxychloride)

I would not treat with any fungicide as that when living media is used instead of dead/axenic media then fungicide is not good for the beneficial microbes. In several cactus studies and publications it is noted that beneficial fungi and bacteria have been found associated with the roots of various cactus species. In nature they grow in living soil. Even a (low temp) tea made from good healthy soil can be used to inoculate a sterile mix though, and thus provide an assortment of beneficial microbials.

- dense sowing (0.35cm^2 = 0.59x0.59cm soil area per seed), roughly equivalent to 100 seeds in 6x6cm pot

I would use about 1/4 that, about 1 seed for a square centimeter, roughly a 5X5 seed grid with a border between the seeds and the pots.

This density works well for me and if you have nearly 100# germination then 100 seedlings in a 6cm pot is going to be very dense and require transplanting months sooner than a more spaced out sowing. Also if any of the seedlings are attacked by pathenogenic fungi or mold the higher densities lend themselves to larger losses. However rot did stop being an issue for me when I started germinating on living media.

- 1-2mm thick pumice topping on seeds (none on Aztekiums due to their size)

I would not use pumice to top seeds, i put the seeds on top of the medium and water them in with (often hard/pH 8) tap water misted from a spray bottle to settle the seeds slightly, I have had excellent results from top sowing seeds of these type of cacti, such as Turbinicarpus.

- wash seeds into mix w/ sprayer (boiled rainwater)

I don't know about boiled rainwater, but the general method sounds good.

- heated propagator w/ 18" grow fluoro (propagator shrouded w/ reflective foil casing)

how many lumens per watt and watts per square meter? I'd avoid low light densities and high light densities. I'd target about 200-400 watts per square meter and use only high efficiency lights. Or sow in sunlight with some degree of shading.

- 16hr light @ ~24-28°C; 8hr dark @ ~5-10°C

you'll find that they germinate well at the temps that you enjoy, but these temps should be effective.

- bottom water w/ dilute (~0.01%) low N fert. (Yates 'Thrive' cacti & succulent), beginning several weeks after germination occurs

I'd begin using a dilute fertilizer soon after the first areoles show up and introduce the plants to more xeric conditions, i would also top water/top feed with a spray bottle and not use bottom watering, I would also use a fertilizer that is average for N, such as a 1:1:1 or a 20:20:20, basically something with equal amounts N:P:K,

Edited by Archaea

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- keep in propagator for 4-6mo. after which humidity is decreased gradually

I'd keep them in the grow chamber until they are either crowded and in need of transplanting or until I moved them into brighter conditions to increase growth rates once they are well established.

Secondly, how much attention do these slow growing species need in the early stages?

It really depends on the set-up, basically they need to be checked on a couple times a week but hardly need any care, just make sure everything is good now and again and if needs be do what you must to ensure optimum conditions are maintained.

I wish to know this as I will be away for 16 days during the end of June to start of July. Would you take the risk of starting the seeds now and being away from them for a couple weeks (when they are ~6 weeks old), or do you think it would be better to hold off until I get back?

Now is fine, it should be easy to ensure that the plants retain the proper humidity for those 16 days, if conditions are ideal, not too moist or too wet and bright enough then you will have zero problems.

People who grow these plants often note volunteer seedlings growing next to older plants where seed fell and germinated, nature didn't make them wimpy or fragile or infection prone. It made them fertile and tough and they adapted to their particular niches remarkably well.

to illustrate the truth of the matter:

Cacti are ridiculously easy to grow from seed, it perfect results can be had without any serious effort or set-up.

Edited by Archaea

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some very helpful info, thanks for posting

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Thanks for all the info everybody, yeah Aztekiums sound testing, but they will be worth it I'm sure.

I think I will stick with the sterile method, I do not like it myself, but at the end of the day we are growing these cacti in very un-natural ways, there is rarely as much organic matter in the soils where these cacti typically grow, but we want quick growth at the end of the day. When I re-pot them I plan on introducing these plants to a highly opportunistic ectomycorrhiza that I have, plus some other miscellaneous soil microbes from the garden, but for now I just want them to survive the highly alien conditions that I, like most growers expose their cacti to during the seedling stage.

I'm not sure on the lumens, but it is a high-out put bulb, it certainly served all my Tricho's well.

Hmm, everything I have read has warned very, very strongly against using high pH water, I have read several times that a water pH of around 5-6, like rainwater is optimal. As long as you live in an area with low pollution, rainwater tends to be the best water for cacti.

Cheers

Edited by Illustro Verum

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at the end of the day we are growing these cacti in very un-natural ways, there is rarely as much organic matter in the soils where these cacti typically grow,

they actually often grown in the shade and shelter of a nurse plant, which raises N:P:K levels above ambient levels, provides some shelter and shade and puts organic matter in the soil

Hmm, everything I have read has warned very, very strongly against using high pH water, I have read several times that a water pH of around 5-6, like rainwater is optimal. As long as you live in an area with low pollution, rainwater tends to be the best water for cacti.

Cacti often grow in areas where the soil has high pH, rainwater is affected by this and the pH of the water in native conditions is a reflection of the media, not of the rain itself.

I've been growing these species for many years and have better results that most people, including quicker growth than the average grower.

You may, with your methods, invite more problems than you solve. Good luck.

Please post your progress and results.

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I agree with the idea of having a mix that is allready stable and controlled with natural bacteria. A good idea if you want to go this route is to leave your container for a week or three after casing your medium before you sow. That way your bacteria will re establish and adjust to the new container.

Keep the moisture in the container up for the three weeks the same way you would after sowing.

Rinsing your seeds in water to remove old sweet and sticky fruit remnants is also a good idea.

Edited by George

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