Accidental seedlings inspiring experiment

[CactusFanDan]

My grow box gets to over 100 degrees at times, but can dip to as low as 55 or so degrees at night. Temperature swings are useful for germination, but most common species will germinate really easily between 70-85 degrees. 100 degrees is certainly excessive and can stop some seeds from germinating, but since I'm also growing seedlings on in there a number of species love it. Ariocarpus, Turbinicarpus, Lophophora, Austrocactus, Uebelmannia, Discocactus, Eriosyce and plenty of others seem to love it hot, while others suffer at these temperatures. Gymnocalyciums are usually the first to pack in at very high temperatures and the soft bodied Copiapoas don't like it that much. I'm sure many others also don't, but I'm not growing them from seed at the moment.

You haven't mentioned light at all yet. What do you plan on using as your light source? The sun is risky if you're using sealed containers, since you often end up with boil-in-the-bag cacti. Almost all young cacti dislike any amount of direct sunlight as well. Artificial lights are useful. As for small-seeded types, then it depends on how small we're talking. Blossfeldia, Strombocactus, Aztekium seeds are the ones in which their size really makes them more challenging, since their seeds are like dust. Everything else is usually fine.

[greenknight]

Seeds arrived, unfortunately the weather's taken a downturn. Checked the temperature in the attic this afternoon, 66 f. - not nearly warm enough. From the forecast, be at least a week before it is warm enough. No surprise, this is the Northwest; wasn't counting on being able to plant before June.

[*Barracuda_52*]

Seeds arrived, unfortunately the weather's taken a downturn. Checked the temperature in the attic this afternoon, 66 f. - not nearly warm enough. From the forecast, be at least a week before it is warm enough. No surprise, this is the Northwest; wasn't counting on being able to plant before June.

Have you given any consideration as to a seed sowing/grow chamber of sorts? Its nice to have something as you can sow the seeds anytime of the yr.

[greenknight]

This old house needs to be rewired, very short on outlets/circuits. Sticking with natural light and heat mainly because of that. I do have a soil heating cable and a grow light, not using them until we rewire.

There's a south-facing window in the attic, should be some position around it that will be good - could always shade them if needed. A sheet of tissue over the top works quite well.

I'm planting Rebutia, Coryphantha, Gymnocalycium, and Oreocerus; no super tiny seeds.

[greenknight]

Got them planted June 1st - all mixed species for this test, I'll have the fun of figuring out the species later . Thought I'd have less chance of getting a whole packet of non-viable seed this way.

The medium is what I use for growing adult cacti, with extra gravel added. I use a locally produced organic potting mix containing worm castings, peat, and pumice (quite a bit of pumice); I mix 3 parts of this with 2 parts of volcanic gravel (contains a lot of pumice, some sand) as my regular cactus mix. For seed starting I'm reversing that, using 2 parts potting mix and 3 parts gravel.

What I'm calling gravel is technically tephra, commonly called volcanic mud flow material. This is Mt. St. Helens country, enormous piles of this stuff were dredged out of the river after the 1980 eruption. It's volcanic rock broken into all different size fragments. It doesn't make very good fill material, too much pumice in it; so it's not in much demand. Works well in cactus mix, though. I just screen it through 1/4 inch mesh hardware cloth, use the coarser gravel that I screen out for mulching the pots. When I first used this for cactus seed starting I also sifted the fine sand out of it, but I decided that was a waste of time - not that much sand in it.

Temperatures in the attic are getting up to around 90 f during the day now, so I'm hoping to see some germination soon.

[iann]

What sort of light are they getting up there? My loftspace gets hot enough (on sunny days probably way too hot!) but is completely dark.

[greenknight]

What sort of light are they getting up there? My loftspace gets hot enough (on sunny days probably way too hot!) but is completely dark.

As I mentioned a couple posts back, there's a south-facing window; I've got them back far enough from it they don't get direct sun and get cooked. I'll adjust the position as I see what color the seedlings are showing.

I'm sure it will get too hot up there in the heat of summer. This afternoon the attic was 93 f, which is excellent. The weather is supposed to stay about the same for the foreseeable future - not that I have much faith in the long-range forecast. Just have to move them if it gets too hot.

First signs of germination today, after just 4 days - one of the Coryphantha seeds has a root emerging. It's in the tray that isn't bagged, which proves nothing - it's just one, and there might be others I didn't see. Won't be able to draw conclusions until I see what the overall germination percentage is. I counted the seeds (tedious!) so I'll be able to determine that precisely.

[iann]

Got to be careful with direct sun on small seedlings, most of them just can't take it. Dappled sunlight maybe, or perhaps a short period each day, but generally bright shade is better for at least the first few months.

[greenknight]

Got to be careful with direct sun on small seedlings, most of them just can't take it. Dappled sunlight maybe, or perhaps a short period each day, but generally bright shade is better for at least the first few months.

I'm well aware of that, which is why I don't have them right under the window, but several feet back. This time of year the sun is very high in the sky, even this far north (almost as far north as England ). They would have to be very close to the window to get full sun, and then it would be only in the morning - trees shade that side of the house in the afternoon.

Saw more germination today, a couple of Gymnocalyciums in the bag have sprouted (edit: turned out I was mistaken about that). Gave the un-bagged tray water for the first time since the initial spray at planting time, as the rocks were starting to look dry. Just trickled a little, gently, from the watering can; the rock mulch served its purpose, the Coryphantha seedling was not dislodged. It now has developed root hairs and is definitely growing.

[greenknight]

Noticed a couple seeds stuck on the rocks in the unbagged tray. I looked for that after planting and didn't see any, so I think they must have floated up when I poured water on them. Washed them down with the sprayer. Might be hollow seeds - I don't know if viable ones can float - but I'm going to stick to watering with the sprayer in case it's a problem.

Several Coryphanthas in the bagged tray sprouted. Some clouds today, 89 f in the attic.

[greenknight]

Now been 10 days, quite a lot of the Coryphanthas are up. They don't all show up in the photos, but I can see 12 (out of 17 planted) in the bagged tray, and 9 (out of 16) in the other. I think I was mistaken about the Gymnos, not seeing any growth there. Hard to tell seedlings from pumice bits at first. Nothing I can definitely verify as germination in the other cells. Weather's been a little more cloudy, only getting to about 80 f up there. Should be better for the Rebutias, from what I've read.

Moved them a little closer to the window, looked like they needed more light. They're now a nice pale green color, as you can see in the photos. First pic is the whole setup - the bag is closed with a twist tie, though you can't see it. As you can see, the window is open with a screen in it, for ventilation. Trusting the weather stays mild. Next is the un-bagged Coryphanthas (slightly out of focus), then the ones from the bag. They're planted clockwise, in alphabetical order - Cory, Gymno, Oreocereus, Rebutia.

- Spence

[CactusFanDan]

Those are seedlings alright! Which Gymnos did you sow? Some of the ones with tiny seeds can be hard to spot at first (saglione and pflanzii). Looking good so far.

[greenknight]

Those are seedlings alright! Which Gymnos did you sow? Some of the ones with tiny seeds can be hard to spot at first (saglione and pflanzii). Looking good so far.

Planted mixed species for this test. Could be anything, probably common species. Iirc there weren't any really tiny Gymno seeds.

Spotted an Oreocereus seedling today. It was in the bagged tray - looking good for the baggie method so far. It's still early, of course.

[greenknight]

There are now 12 in each Cory cell. There was one in the unbagged that I must have missed before - it's short (doesn't stick up above the gravel) and dark green. The seed hull had already fallen off when I spotted it, so it had been there a while. A definite oddball, which is great! 2 more normal looking ones sprouted after that, for a total of 12.

3 in the bagged Oreocereus now. One I spotted as a little green speck stuck on one of the pebbles. It was so tiny I doubt it could have grown a long enough radical to reach the medium, so I tried to brush it off with the end of the twist tie. It stuck to that, so I scraped it off on one of the pebbles, got it at least close to the surface. There's now a healthy seedling there.

Nothing from the others yet, but it's only been 15 days.

[greenknight]

There are now 7 Oreos in the bag, only one unbagged.

Nothing else has sprouted. In fact, I'm down one Cory in the unbagged tray. There was one weak one that never stood up and got plump like a healthy seedling, and now it's gone. It got hot today, and I guess it just shriveled up; I can't even find the remains of it.