A stressful seedling story

[geophile]

Last year ( and a couple months change) I started some cacti seedlings from a Ferry Morse packet. I sterilized the soil and baggied them in an east window sill, The varieties are/were Saguaro, Hedgehog, Fishhook barrel, Dollar Prickly Pear, Desert Prickly Pear, Christmas Cholla, Cane Cholla, Santa Rita Prickly Pear, and Cardon.

Anyway. The first couple months were great.They fleshed out nicely and were bright green.

Then I noticed some rot starting on some of the seedlings, so I gradually opened the baggie, removed the bad ones and began daily misting/wetting instead.

But I kept losing seedlings and so I took one that was apparently sick out of the soil. I had fungus gnat larvae.

I removed all the seedlings carefully and gently washed them and their roots, and destroyed the ones that had larvae in them. Then I sterilized the soil again, transplanted the seedlings back into the now sterile soil. They survived and even seemed to put on some extra growth. By the way, as an experiment, I took 2 seedlings and put them in richer, unsterilized soil.

When late fall came around I got a 45 LED panel light (red and blue) and put the light on them. I didn't think that would be too much light, but most turned some shade of pink/orange/red. I moved them away from the light a bit, and they seemed to green up slightly, but some of them never fully changed back again nor do they grow much, although I see what I think are new spines on all of them.

Strangely, the 2 seedlings I potted in richer soil turned green and grew double the size of the others under the same light conditions. They also greened up.

So, before the summer started, I thought, why not, I might as well repot them all in richer soil since it worked for the other 2. So I mixed some garden soil into the cactus mix I had and put them outside in the shade.

I've been watering lightly about once every other day. They seem smaller than they should be for being over a year old. You think they are just stunted from how much stress they've had to go through? I want to just put them someplace and leave them alone for a while. In the state they are in, what conditions would be best for them to grow optimally?

[greenknight]

Not looking too bad, under the circumstances. When they get so stressed that they turn very red and stop growing it can set them back for months. These are not all that far behind. Some of them still look too stressed, though. The light may yet be a bit strong - but I suspect the watering is not adequate.

Watering from below is best at this stage, to encourage deep root growth. The system I recommend for your situation is this: When dry, set seedling tray in a pan of water about half the depth of the soil in the tray. Watch - when you see moisture appear at any point on the surface of the soil, remove from the water an let drain. The moisture should spread out and the whole surface become damp. Repeat when they become dry again. As the plants get older, let them dry out a bit longer between waterings.

[Grimm]

Could I ask how you sterilised the soil?

[geophile]

Could I ask how you sterilised the soil?

Sure, I microwaved it in pyrex for 7 minutes, stirring halfway through.

[geophile]

Not looking too bad, under the circumstances. When they get so stressed that they turn very red and stop growing it can set them back for months. These are not all that far behind. Some of them still look too stressed, though. The light may yet be a bit strong - but I suspect the watering is not adequate.

Watering from below is best at this stage, to encourage deep root growth. The system I recommend for your situation is this: When dry, set seedling tray in a pan of water about half the depth of the soil in the tray. Watch - when you see moisture appear at any point on the surface of the soil, remove from the water an let drain. The moisture should spread out and the whole surface become damp. Repeat when they become dry again. As the plants get older, let them dry out a bit longer between waterings.

Excellent, thanks for the tips! I'll post updates as they grow.

[7george]

These seedlings look like a mix of Echinocactus grusonii, some Ferocactus and something else. Do not expect of them to grow faster. I would not rush them. My soil I use for small seedlings like these contains some sand and vermiculite to bound water in the mix longer and not to water every other day but 1ce a week or so. Seedlings of Echinocactus grusonii and Ferocactus are very drought-tolerant and can stay dry for several days or more even in the summer. You can reduce sunlight to get greener colour of seedlings using some shading or exposing these just to morning sun.

Sterilizing of soil is helpful mainly for covered seedlings at first weeks or months or if you expect some parasites like nematodes to present in the soil.