Depending on the seed you'll get germination within a few days to a couple of weeks. Since this idea came to me it has made gardening outdoors a little easier for me. If I'm growing a plant I've never grown before I may not be familiar with what the seedlings look like. Since I know that what is planted inside the paper rings are seeds I sowed, I know it is OK to pull any seedling growing outside of them because those would be weeds. This is also useful when you have non-gardeners helping you do things in the garden like pull weeds. You can just remind them that anything growing inside the paper seed marker is a plant and should be left alone.
This also helps a great deal when you're planing out a garden because you can visualize where plants will grow after you've sown them. You can lay out perfect rows for herbs and vegetables and even geometric patterns in your garden too when you know where the seeds are going to get planted and space things accordingly. You could even write the name of the plant on the tube and it should last long enough for you to identify them later.
I noticed that this also cuts down on the amount of water I use because instead of applying water to where I think
I may have planted seeds I can water where I know
I planted seeds.This reduces the amount of time I spend watering and how much water gets wasted because it is only applied to the area inside the paper ring.
Finding a use for these cardboard tubes keeps them out of the landfill. Adding them to the dirt provides organic matter for worms and other beneficial insects that break it down and turn it into soil for your garden.
Hope you find this Instructable useful and can apply it in your garden. If you live in the Chicago area I've got a new garden blog at Chicago Garden
that I invite you to visit and participate in.