Blueberry (First timer)

Its alright, depends alot on the quality and state of the seed. If in a week you still font see anything i would worry, till then its only normal. As you can see you WW is a bit slower than your BB, the tap root on the WW was much smaller. If you planted at the same soil depth you should begin to see her in 2-3 days max. Dont worry If she has already sprouted the taproot your chances just improved alot.

Something is stressing her a bit, but don't throw in the towel just yet. Feed her just enough to stay moist. She is way more focused on building a root structure right now anyway and that's going to be what gives you results in the end. Don't overwater and don't hit her directly with a fan.

No, if it loses it first true leaves, that's it, no new ones will ever grow. Their "disappearance" was likely due to too high a humidity, especially if you had covered the newly hatched seedling with cling film or other humidity boosting cover. Cannabis seedlings do not need artificially high humidity to grow, but they do need good air exchange, something that can not happen when under a cover of any sort. Having a light on can also raise the temperature under the cover considerably, literally cooking any new growth or causing moulds or fungus to attack the plant. Cannabis is not a rain forest plant and growing seedlings under humidity domes/sweat lodges is one of the most frequent mistakes I see in Grow Diaries. Only cuttings/clones need extra humidity, and only for a short time while they are waiting to form a new root system. Just think about what happens in nature, cannabis grows in the open air, there are no little elves or fairies running around covering cannabis seedlings with little humidity domes or plastic film. Most Idicas come from the middle east, a very dry climate and most sativas come from equatorial countries and grow in the "dry" season, both environments are very low in humidity. Cannabis needing humidity is an outdated concept from the 1960s when pot was coming from South East Asia (and people generally had very little actual knowledge about cannabis), so people though "jungle", whereas the pot came from low land areas and grown during the dry season. This myth about cannabis needing humidity has strangely persisted for the last 60 odd years and is largely an urban myth. I also believe people are wasting vast amounts of money by unnecessarily having and running humidifiers in their grow tents/spaces. Cannabis actually prefers a dry environment from mid flowering onwards, and will produce the largest amounts of trichomes when its is arid at the end stages of flowering. Hope this helps, Organoman.

Transplant them into decent sized pots, those tiny cups are dreadfully under sized for proper root development and only really adequate for the first 5-7 days of growth. Pots about 4 inches across and 5 inches deep are far more suitable and have enough room and volume for great root growth and enough space for 3 weeks of development. You can't grow an elephant in a canary cage! You also need to start feeding them with proper grow nutrients, half strength to start with, the supplements you are now giving do not contain any major nutrients in any great concentration. Seaweed, silica and root stimulants will not provide your plant with the building blocks it needs to grow properly and they all lack adequate amounts of nitrogen, phosphorous and potassium (the major nutrients) that your plant needs to grow. At the moment, what you are giving is like feeding soup broth to a cage fighter, who really needs steak and carbs to perform to their best. Soup broth may prevent death, but will not provide the energy needed to perform at A level sports. It is all about nutrition and an adequate and balanced diet. Hope this helps, Organoman.

Yes, this is a problem, your plants are suffering from lack of nutrition and no doubt starving. Please see my answer that I posted in your other question for more clues to guide you towards healthy and happy plants. After looking at your diary, it seems your light should be adequate, just your feeding is missing the mark, as well as the cups being a dreadfully unsuitable size for proper seedling development. Cheers, Organoman.