Here is my FIRST Instructable posted... I hope you find it useful.
Seeds started before the last day of frost, OR environmentally sensitive seeds, OR seeds that must be surface or shallow sown, have special needs. They must be kept moist, warm and lit. The window sill greenhouse allows gardeners to use their green thumb throughout the year. Even in the middle of winter!
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Step 1: Get Your Materials...
To-Go Container; Potting Soil
Seeds; Heat Source; Screwdriver
Catch Tray (Serving Tray w/Lip or 5-Gal Bucket Lid)
Window Sill or Light Source
Step 2: Prep Your Container
If your To-Go Container is made of a breathable material like pulp, paper, or cardboard, it will breathe. Sprouts need air around their roots to grow properly, adding drains or using porous material lets this happen.
Plastic containers need to be perforated. I prefer to do this outside with a screwdriver and a hand-held torch. If you do this indoors, be sure to have a fan to disperse any plastic fumes. Heat the tip of the screwdriver and poke several holes evenly in the bottom. See the pic for an example. They should be spaced to allow uniform drainage and air flow.
Step 3: Fill the Container With Potting Soil. Moisten.
Fill the container 3/4 or more with your favorite seed-starting soil: store bought or home made. The more you fill it, the more room the roots have to grow. Leave a little room so you can add moisture without running over.
Now water the soil. No seeds yet. Watering after sowing can move, bury, or dig up the seeds or damage tender roots. The soil should be fairly moist but not dripping. The purpose of the greenhouse is to reduce water loss and maintain a warm environment.
Step 4: Plant Seeds
You have seeds. They need planting.
With dry hands... Pour several seeds into your hand and gently "pinch them up" and place them according to the methods recommended. OR you can evenly spread them by shaking them across the surface.
There are several species that need to be surface sown and need light to germinate. These include poppies, foxglove, tobacco, hollyhock, mint, primrose, Venus flytraps, carnivorous pitchers, and more. If your seeds need to be buried only 1/16" or 1/8", just sprinkle a little more dry soil on top and gently pat down. Don't worry. The moisture will spread upwards.
If you can't seem to find any exotic seeds in your neighborhood hardware store, go on-line and look for something interesting. I usually choose eBay and look there.
Place the To-Go Container on the tray and place it in a window sill. The seeds only a couple of hours of light per day, so look for an East or West facing window or one with shade during part of the day. Too much direct sunlight can cook the seeds, so be sure to check it a few times during the first days to see if the window chosen is OK.
Water gently if you notice the soil drying or there is no condensation inside the container lid. Use a small measuring cup or spray bottle. Don't flood, just moisten.
But Wait!!! You don't have a lid? No sweat...
Cut a couple of beverage straws in half. Poke them into the corners and center to support the cover, sticking straight up... Now slide the container into a Zip-Top bag blow into it to inflate it and zip it closed. In a bag, it will not need a drain tray. Zip-Top bags come in sizes up to 2-Gallons and larger, and are reusable.
Step 5: The Little Babies! Sprouts Ready for Transplanting...
Once the seedlings are "mature" enough to to be transplanted, you can use a small fork, spoon, or even chopsticks. The trick is to pick up the soil with the roots intact and move them into a new container prepared with fresh soil and pre-moistened.
Recommended Reading? Western Garden handbooks Square-Foot Gardening
Even seed catalogs have a tremendous amount of seed planting information and species tips.