As high as you can get it. 80-90% is good.How high should the humidity be when the seed first sprouts and I put it in rockwool
Yes, but that wasnt the OP's question.it's almost impossible to get 80 in winter climates and imo, not worth the effort
that guy lost meYes, but that wasnt the OP's question.
IMPORTANT: Don’t cover pots with plastic wrap, don’t use a humidity dome to seal off the pots, or place pots/rockwool cubes in a propagator that’s completely covered! This prevents fresh air exchange, raises humidity to excess levels, and easily facilitates the spread of fungus. The seeds then rot before they can germinate. Excess humidity coupled with lack of oxygen is the #1 cause for poor germination results!
If you germinate your seeds at room temperature, and have properly watered the substrate, there is no need to be concerned that it will dry out overnight. Only the substrate requires sufficient water for the seeds to germinate - the outside humidity can and should be be low to moderate (i.e. max. 55%). Low humidity in the room does not interfere with germination or healthy seedling growth. Remember: cannabis is not an orchid! Fungal spores are everywhere: in the air, in substrates, ... and they await the conditions to spread and attack organic substances such as seeds or the roots. Common fungal infections are pythium and fusarium. Young seedlings are also prone to such infections because their cell tissue is very soft. Over-watering and/or high humidity trigger such diseases like “damping off” which quickly kills seedlings.
Yeah I can vouch for that from experience. I domed my clones and would burp and mist them a few times a day and within a week I had white mold growing on my peet pellets. As soon as I un-domed them and just misted them 4x a day they snapped out of it, mold died and they did fine. =)Seems as if I've been mentioning this a lot lately: seedlings (unlike clones) do not need high relative humidity to sprout or thrive. Indeed, RH is best kept low for seedlings and covering with a dome is not advisable.
http://www.mandalaseeds.com/Guides/Germination-Guide
what he saysAs high as you can get it. 80-90% is good.
Nullis is correct about damping off. I didn't think to mention that. You get incredible growth from seedlings in the first week under a dome and on a heat mat, however, you really have to be cautious that your medium doesn't stay overly moist. You can avoid damping off by removing the dome a couple times a day and using it is as a fan to circulate the stale air around your seedlings. Also I only water my medium once and I let it dry out over the course of the week while they are under the dome and I only use a foiliar mist once or twice a day during this time.Heat mats are great for seedlings, and I don't think a ventilated dome is as likely to present any problems but seedlings in excessive humidity are certainly at increased risk of damping off or other less serious fungal issues such as development of unwanted mold or mildew on the medium.