Nullis
Moderator
Whatever container you're starting in (plastic cups are good as they are 4"+), it's good to fill it all the way to the very top with soil (so that the roots can utilize all available space).
Also, I disagree with using a spray bottle to water seedlings. Watering seems to be a huge issue for many new growers when it doesn't necessarily have to be. I would argue that using a spray bottle to "water" could be counter-productive. You may get into the habit of just misting the soil surface when it looks like it is getting dry, or just for the hell of it. This could lead to dry spots elsewhere beneath the immediate surface (roots wont grow where it is too dry). Thorough watering with proper wet\dry cycles is important for healthy root growth. Ideally you want to water thoroughly or until you see some run-off, each time you water. How fast it dries out is going to depend on container size, media, temp, relative humidity, lighting, air flow and age of the seedling. As the seedling grows more roots, it will start to call for water more frequently, until ready for transplanting. Wait until the container has lightened up considerably (lifting is a good way to check), and top has dried out (for the most part), just don't wait until it has dried out COMPLETELY. There should always be some level of moisture throughout the soil at all times.
Potting mix that is too dry will seem to repel water at first, and it often comes this way initially (out of the bag). If you wait until the mix gets dry as a bone and starts to shrink away from the edges of the container, that's no good. When you do go to water it will appear to pool up on top, run down the sides, or otherwise piss right thru the container (without actually being absorbed). In these cases it is helpful to mist the soil mix to help moisten it, or to water with a small volume prior to planting in and then water thoroughly.
Also, I disagree with using a spray bottle to water seedlings. Watering seems to be a huge issue for many new growers when it doesn't necessarily have to be. I would argue that using a spray bottle to "water" could be counter-productive. You may get into the habit of just misting the soil surface when it looks like it is getting dry, or just for the hell of it. This could lead to dry spots elsewhere beneath the immediate surface (roots wont grow where it is too dry). Thorough watering with proper wet\dry cycles is important for healthy root growth. Ideally you want to water thoroughly or until you see some run-off, each time you water. How fast it dries out is going to depend on container size, media, temp, relative humidity, lighting, air flow and age of the seedling. As the seedling grows more roots, it will start to call for water more frequently, until ready for transplanting. Wait until the container has lightened up considerably (lifting is a good way to check), and top has dried out (for the most part), just don't wait until it has dried out COMPLETELY. There should always be some level of moisture throughout the soil at all times.
Potting mix that is too dry will seem to repel water at first, and it often comes this way initially (out of the bag). If you wait until the mix gets dry as a bone and starts to shrink away from the edges of the container, that's no good. When you do go to water it will appear to pool up on top, run down the sides, or otherwise piss right thru the container (without actually being absorbed). In these cases it is helpful to mist the soil mix to help moisten it, or to water with a small volume prior to planting in and then water thoroughly.
