Accidental seedlings inspiring experiment

[greenknight]

I've grown cacti from seed before with some success - they needed babying, close monitoring of the moisture level, etc. I recently had an experience, though, of growing cactus seedlings without trying, which has me thinking I may have hit on a better way to do it.

I mulch my cactus pots with coarse gravel/small rocks - easier to remove and replace when repotting than fine gravel. One plant - pretty sure it's a Parodia scopa - which produced a ton of seed, had some fall into the pot. These washed down between the rocks and sprouted, which was no surprise - easy plant to grow from seed. I figured they were doomed, since they need more moisture than the adult plant and I couldn't dig them out without killing them at that early stage. Between waterings they would dry up, I was sure.

They didn't, though. Most of them survived and grew grew quite happily there. I didn't need a bunch more of those, so even when they were large enough to transplant I left them alone to see what would happen. Several came through the winter just fine. After two years the mother plant needed repotting, still had several seedlings with it. One was much more robust than the others, so I saved that one and tossed the rest. Attached is a picture of my accidental seedling in its tiny starter pot, along with one of it next to a cutting from the same mother plant in a 3 inch pot.

My theory is this worked because moisture doesn't evaporate from the medium underneath the rocks, so the surface doesn't dry out before the rest of the pot. It got watered when it was fairly dry, but never got bone dry. Plus, the seedlings were sheltered by the rocks, pockets of humidity were trapped in the cracks where they were growing. Damping off fungus grows only on the soil surface, but the surface wasn't exposed, so no fungus problems. The rocks also supported the seedlings and kept them from washing out.

I plan to experiment with this as a method of growing cactus from seed - prepare pots/trays of starting medium, and carefully cover the surface with a single layer of sterilized pebbles (say, 1/4 to 1/2 inch size). Sprinkle cactus seed thinly over the top, and wash it down with a sprayer - large seeds probably need to be pushed down with a toothpick or something. Sprinkle fine sand very lightly over the top, and wash it down again. Place them where they're to germinate.

Obviously, a lot of fine tuning will be needed - how much to water, whether covering with plastic at first is still a good idea, are open questions, and no doubt other questions will arise. Anyway, I'm going to give this a try - I'll report the results as they become apparent. Wish me luck.

[iann]

Most of them survived

There's the kicker. Most of them *didn't* survive. Just the ones that got lucky survived. Works well if you have enough seed, not when you have a packet of 5 that you just mortgaged your home to buy.

[*Barracuda_52*]

Most of them survived

Works well if you have enough seed, not when you have a packet of 5 that you just mortgaged your home to buy.

LOL!! Ian you crack me up but hey its somewhat the truth when ya only have 5 or so seeds to sow and ya wait and constantly check to see if they germinated and then pow only one seed germ's outa those 5 or so seeds its a real pain at times BUT well worth it in the long run.. I remember paying for some seeds that never even germinated such a loss pooooy.. I will never get seed from that person again.

[Pilif]

I have to agree with Ian here. The 'classic' baggy-method for starting seeds works perfectly fine, if you do it right you get 50-100% germination rate, easily ('difficult' species excluded). The reason this works is because you have a very high level of control over the germination environment, allowing you to create circumstances under which the seeds germinate readily (moisture, temprature, light...). By sacrificing this control for convenience (i.e. less monitoring, though you don't even need that much monitoring with the baggy-method) you're bound to get a lower germination rate.

On a side note: generally, cactus seeds need light to germinate, cover them up too much and not much will happen.

[greenknight]

Germination is not the problem, it's the care from the time they germinate until they're old enough to stand a little drying that gives people trouble. I'm not necessarily going to abandon the plastic bag for germination. I plan to try it both with and without the plastic to see what works best.

Most of these seedlings did survive to a size where they could have been transplanted, I just didn't - I was having some health problems, and I didn't want to deal with them. I don't know what the germination rate was, since I don't know how many seeds fell into the pot - this is one of the things I want to determine.

The seed are not going to be covered deeply - I plan on sprinkling a very small amount of sand on them, though it may not be needed.

I'm not going to experiment with expensive seed, of course - I ordered 4 little packets of seed from thecactusstore.com, about 100 seeds at a cost of $10.75 with shipping. If it doesn't work, it won't be that much of a loss.

[CactusFanDan]

If you cover your seedlings (ie baggy/fleischer method), then you're more or less guaranteed to get them to adulthood. My seed growing never went very well before I used the baggie method. I don't normally cover my seeds with anything, unless they're Ariocarpus, or huge, chunky Opuntiad seeds. Ariocarpus get a thin layer of grit to help them send their taproot directly into the soil.

Good luck with your seed growing.

[Peterthecactusguy]

lol I didn't even really "cover" O. basilaris seeds and I got 18/20 to Germinate. I think that 17 are viable, but who knows. one is flipped over and so who knows if it will "survive" or not. :)For smaller seeds I don't cover them AT all.

[greenknight]

Thanks for the feedback, Dan and Peter. Maybe I will skip the sand covering.

[iann]

No sand. No anything in my experience. I've experimented with grit as a covering or just somewhere for the seed to nestle with universally terrible results.

The whole point of sealing up the seedlings under plastic is zero maintenance. You provide enough light and enough heat, then leave them alone for a few months.

This is with the small desert cacti. Opuntias are big seeds and big seedlings, cover them lightly and no need to pamper the seedlings.

[greenknight]

Every source I've ever consulted said you have to give them some air once they're well sprouted, to avoid rotting. Are you seriously telling me you leave them sealed up for a few months?

[Pilif]

yes. Everyone that tells you to give them air once they sprouted (to prevent rotting) didn't sterilise their soil...
I keep them in bags for a couple months, up to a year.

[iann]

Every source I've ever consulted said you have to give them some air once they're well sprouted, to avoid rotting. Are you seriously telling me you leave them sealed up for a few months?

Yeah, every source you ever consulted that had never grown a cactus from seed Seriously, there is some complete rubbish written on the internet, and even in cactus books. Lots of people just keep repeating the same old stuff, but never actually checking if it is true. Microwave the soil (moist soil!) so it won't go green for a long while, then seal it all up and away you go. Months at least, a year or more with slow species. Very few will be unhappy in those conditions, and those are some really difficult species. You might also want to rinse the seeds in peroxide or dilute bleach, to stop anything on the seed coats from growing. I don't and usually it isn't a problem, but especially with habitat seed fuzzy fungus things can grow and give you a scare even if they aren't actually harmful.

[CactusFanDan]

Leave the vast majority of them in a totally sealed container for months to years. Provided that you sterilise the soil you are sealing up prior to use, then it works great. I always end up opening the bags/containers to get a better look anyway, but I still close the containers up again after having a look. Seeds can be soaked in peroxide to help prevent anything nasty appearing. I usually like to use peroxide solution instead of just water when soaking the pots. I only do that, though, if my sterilised soil mix is dry.

If you decide to try growing seedlings in a 100% aggregate mix, then there's no need to sterilise, since your seedlings are unlikely to rot and fungus is unlikely to grow. It's harder to grow them like this, though, since you need to pay attention to fertilising properly and stuff. I'd rather be lazy and leave them for 6+ months on their own.

[Peterthecactusguy]

btw as an aside in some of my conatiners which I don't think were sealed as well as I thought they would, I have had to water them ever so often. So far the only big problem I have had? I lost an O. basilaris to rot cause it's dang seedleaf was resting on the soil and turned black. Plant was removed, and just for safety I let the container dry out for a couple days. I gave them a light misting today. There were a few fungus gnats in the container, but it wasn't from my soil.. they came from someone else's soil.. I think.

[greenknight]

Microwaving the growing medium was my plan already - so much faster than baking in a regular oven! Fewer complaints about the smell, too.

I can see how you can get away with keeping them sealed up if everything is well-sterilized, but there are fungus spores in the air. Occasional loss due to rot does happen, I gather from some of your earlier threads and Peter's post above. Anyway, I'm going to plant 2 identical trays; one will be bagged, one not; we'll see how the results differ. I'm going to use 4-pack cell trays; the cells about ideal size, and they're very stable. I can cut them apart when I need to separate the different types.

The point of the gravel is to provide the little seedlings support and protection after they germinate; it will be interesting to see if they germinate well without any more cover than that, but that's not the main point. The rocks will keep the seedlings from falling over or washing out, when they're out of the bag it will keep the surface from drying out and prevent crusting, and it will deny fungus spores and egg-laying gnats a place to land on the surface of the medium. Even if a cat walks on them, the little plants won't be crushed - not a joke, this happened.

I'm going to germinate them in the attic - nice and warm, and the cats can't get in there, pretty sure I've got the squirrels blocked out now. Need to bring them down from there before any very hot weather, I imagine - how much heat can they take? My seeds should arrive tomorrow or Monday. Not doing any Opuntias; as was pointed out, they don't need babying anyway. Small-seeded types are what I'm concerned with.

Thanks again for all the useful feedback.