baggy tips?

[nona]

I grow my seeds in a 6cm pot and place in close fitting ziplock bag. It then goes into a light box.

I find too much moisture and the seeds or newly germinated tend to rot. Not enough and the top of the soil appears dry and little germinates despite being plainly moist several mm down.

Could the small bags be creating too harsh an environment?

Would be interested in any suggestions. Thanks.

[esp_imaging]

The baggy environment is perfect for mould and rot to develop. So it is generally recommended to sterilise the compost and containers before sealing them.
I like to use microwaveable containers - I fill them with the damp compost, microwave them for a few mninutes, let them cool (still in the microwave) and then spread the seeds over the top and seal up, giving minimum changce for fungus spores to enter.
The compost should be thoroughly damp but not waterlogged.

[7george]

Dry surface means there is not enough water in the baggy or lamps create too much heat from the top. If you decide to add some water into it quick it must be sterile too.

The baggy environment is unnatural even knowing that seedlings are more moist tolerant/needing but this is our way to achieve some higher surviving & growing rate. In habitats seedlings of many cacti survive not every year. Long moist and warm periods are needed to reach critical mass or size to survive during the dry months.

[nona]

Sorry for the delay, I hadn't updated my email it took a while to sort out.

Thanks for the suggestions. I've definitely had issues with larger seeds rotting rather than germinating in the hot moist environment e.g. 3-4mm p.pringlei seeds. Whereas tiny melocactus seeds seem to need a lot of moisture. All my seeds are bought so I can't vouch for their freshness.

What mix I should be using? I assume a lot of silt and small organic particulate will tend to hold more water. Should I add antifungal powder? I read cinnamon powder is supposed to help in that regard.

[teo]

I have found that a total non-organic mix mimimizes the problems with mold on the surface (sterilized or not). i use a mix of vermiculite and cat litter (of the burned diatomaceous earth type) + some silt.

[nona]

I have found that a total non-organic mix mimimizes the problems with mold on the surface (sterilized or not). i use a mix of vermiculite and cat litter (of the burned diatomaceous earth type) + some silt.

While I've read of such mixes I haven't tried it. When would you transplant out the seedlings as I imagine there won't be much nutrients to sustain them?

[teo]

That depends on the size of the seedlings. I remove the bag when they are big enough (maybe a few months usualy) but try to keep them as long as possible. You can always add plant nutrients in the water at that stage. (This is an example of an earlier mix without vermiculite but still a very high percentage of non-organic mix)

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[ElieEstephane]

I did an experiment with baggies where in one pot i used sieved 3-4mm grit and in the other pot i used the sand i got from the sieving process. The sand was washed from all fine and dust particles. Both pots were not sterilized.
In the "sand" pot, i've had severe problems with algae since months 1 and 2 in the baggie and had some dampening off.
In the grit pot, im in month 5 now and have barely (if any) algae and fungus problems. Every couple of weeks some algae occurs one a particle or 2 in the soil so i just remove that particle and seal again and all the problems are gone.
I experimented last year with 2 pots of compost. The 1st pot i had some sort of outbreak where most of the seedlings turned monstrose or double headed. In the other healthy pot, the seedlings were huge with incredible growth rate. However, it was very hard to control humidity with organic matter so lots of seedlings were dead.
In conclusion:
Sieved grit: slow but very reliable. Strong seedlings
Fine mineral soil: terrible, fungus and algae outbreaks, high moisture holding
Pure organic: plump fast growing seedlings. Humidity hard to control. Danger of rot
1:1 organic and grit: didn't find any benefits over pure organic.

[stefan m.]

I germinated a pereskia in a plastic cup in a freezing bag sealed with a paperclip.
The plant doesnt seem to have issues with mold and what not, but other cups got algae and mold.
I used the same mix for germinating other plants in plastic trays
(peat+coir+perlite mix 50%, vermicompost ~17%, rest was fine sand, all sterilized).
In the trays ive had germination. In the cups, not so much.

[nona]

Thanks very much for the responses and pics. It has certainly given me something to think about. Your experiences, good and bad, is exactly the detail I was looking for. I'm now more confident as to what to try next.

[nona]

An update. A week or two earlier I had sown a variety of seeds using mostly organic material. With nothing to lose I sifted out all the seeds (horrid work) and moved them to a 3-4 mm gravel mix with a pinch of soluble fertilizer. Despite the small amount of water used I was amazed how the seeds retained an even coating of moisture.

Amost immediately seeds which had shown little sign of germinating began doing so. I'm sure the hot humid nights helped but even so the change has been dramatic. I note seedlings quickly develop long roots due to the gaps between the gravel. In all I'm very pleased with the results so far. I hope to post updates and pics as things develop.

[nona]

While I'm getting better germination using inorganic substrate (1.5 to 2mm quartz / river gravel) I find the seedlings start to rot after a week or so. Already using a minimum of water. Beginning to think it's the environment. Using 2 inch square pots 2/3 to 3/4 full in a very close fitting ziplock bag. Temperature 25 to 30c. Perhaps I should be using a larger bag or less gravel?

[esp_imaging]

And are you sterilising the mix?
If not, it's the first thing to try.

[ElieEstephane]

Remove infected seedlings and maybe try peroxide spray to disinfect. Seedlings in a gravel mix should be very resistant to rot i usually leave my seedlings up to 6 months in the baggy with little to no rot knowing that i don't sterilize anything.
The only reason i can think of for rot is very high humidity? Are your seedlings looking pale or whitish? That's a telltale sign for very high humidity.
These seedlings are pushing 5 months now in the unsterilized baggy with 0% rot.

[esp_imaging]

The only reason i can think of for rot is very high humidity?

Fungus spores in unsterilised medium, or unsterilised water, would be an obvious reason.
I'd guess the tendency for these to occur will vary widely from place to place. If they aren't as prevalent in Lebanon as other places, you are lucky, but your growing conditions (and prevalence of rot-causing organisms) may not be the same elsewhere.