Last summer I made my first crosses, so I was delighted to see the seeds germinating a few weeks ago. They are in an unheated garage that has about the same temperature as the fridge at the moment. When they germinated I placed the seed on top of potting soil in a small pot. The pots I placed in a plastic mini-greenhouse in the window sill inside my home where it is about 70F. Most developed a root and started to lift themselves up, but then about half of them were covered with a grey fungus overnight and died. From one cross 8 seeds germinated and now I have only one seedling left. When the first true leaf starts to form they seem to be safe.
Pierre Rutten suggested it was botrytis and that I needed to get the moisture down and ventilation up so I removed the cover. It didn’t seem to help much. Seeds that germinated later I placed in a mini greenhouse in the garage, hoping that the colder temperature would stop the fungus from overtaking and killing a seedling so quickly. I have less mould in those batches but still some. I just took of the lid of the greenhouse in the garage because it was quite wet inside. I hope that keeping the moisture and temperature down will help.
Is this normal? Is something wrong with my set-up? I know some of you (or at the rosarian’s corner) cover their pots in a baggy, which seems much more of a perfect climate for moulds to develop than my set-up. Could it be something in the potting soil?
Any ideas I can try?
It happens often with me…
I’m not bothered if I have a bunch of seedlings from one cross, but extreamly upsetting if I have only a few.
My only seedling from Basye’s Blueberry and (Queen Elizabeth X Basye’s Legacy) didn’t make it.
Try a drop of hydrogen peroxide.
You pay less than a dollar for a big bottle of it at your local drug store.
Your humidity is too high. Occasionally a fungus will overtake the little seedling even in a warm, dry room, but it shouldn’t happen that often. Keeping them in a cool area, esp. with a cover would only increase the humidity. I’d try a warm, dry spot if you have one. And don’t keep the soil too moist. Rose seeds don’t need humidity once they germinate and do well in a warm, dry climate so a nice sunny window with no cover is perfect. I live in the desert so I should know!!!
I won’t claim as much experience as some listed here, but I have been raising seedlings for several years now. I haven’t lost many in my basement, and I don’t believe I’ve lost any to boytritis or damp-off. I stratify my seedlings in paper towels. I wait until the cotyledons are free of the seed coat to plant. I have sometimes pried the seed coat off, but I have lost seedlings this way. I pot the seedlings up in 3" peat pots and (ideally) premoistened potting mix. I put the pots in seedling trays and water them from the bottom. I occasionally mist the seedlings with a spray bottle, but never cover them over. My basement runs about 65 degrees F.
Hope this might help. Sounds like your soil may be too wet, and the air too humid around your seedlings.
I would blame the potting soil and/or the pots. Pots can be sterilzed with a little bleach and water and only use new clean seed starting medium such as Promix. Also water from the bottom only and only enough to dampen the medium.
Sorry that your precious crosses have gotten off to a bad start. Don’t be discouraged, my seeds are still in the fridge and out of the thousands I’ll be happy with one healthy plant.
Try watering with 1 part of the store-bought hydrogen peroxide to 9 parts water. Also, let the soil dry out slightly between waterings.
I lost every seedling two years ago. The above method works as long as you don’t completely drench the soil. In serious cases, I use a fungicide called Banrot.