One of the ways I dry lettuce, broccoli, radicchio is by covering and tying off with newspaper. Pull the plant out of the ground, cut off the root ball, then save the top of the plant with the dangling seedpods by wrapping the plant with newspaper, and tie with a string the top of the stem. Hang on a wall in the house or where ever is convenient to hang drying plants. This is usually a temporary method of drying, as this could encourage mold. The proper method of storing or drying seeds is by taking the shells away from the seed, dry for a week, then storing in an envelope, plastic bag, or glass jar. Keep seeds in a cool, dry place; and of course you can store seeds in the refrigerator or freezer.
Typically it is best to let all seedpods dry naturally on the decaying plant. Once the plant dies and becomes brown and brittle, the seeds should have dried well enough that you can store the seeds indoors. There are several methods of drying different plants, and I'll show you different ways I dry each plant and their seeds.
In the picture below, I have covered Radish plants, Lettuce, Spinach, and Radicchio in newspaper and tied with a string.
We prefer to allow the beans dry naturally on the plant, but you can harvest bean pods green and allow them to dry by stringing pods together (which we have done in the photo below). It is best to dry beans and other seed pods on wracks that will ensure aeration and prevent molding.
Here I am drying onions and beans on newspaper, and corn drying in a box.
Normally I dry cantaloupe, watermelon, and squash seeds by scooping them out of the fruit, rinsing them in water, then laying them out on a paper towel, wash cloth, or newspaper. After a week or two of rotating the seeds, they should be ready to store. Pepper seeds can be dried as you would squash or melon; but pepper seeds will dry faster than other fruits.
Because a coating on the outside of tomato seeds prevents the tomato from sprouting on the inside of the seeds, saving seeds from tomatoes requires (as well as cucumbers) a fermentation process. Fermentation is one way of breaking down the coating.
Use your biggest, ripest (mature), and best looking tomato to save seed from. Start by scraping out the seeds into a glass jar, and avoid big chunks of tomato. Fill the jar with 1 and a half times as much water as you do tomato seed and juice. Then cover the jar with a coffee filter or fabric that will allow the jar to breathe; then secure with a rubber band or hair tie. Keep the jar in a cool, dry place out of direct sunlight. Everyday, shake the jar of seeds and juice. A scum will develop on top of the juice, and of course that is normal. After four days or so, strain the juice from the seeds in a sieve. Clean the seeds with water. Spread the tomato seeds on a paper plate or paper towel for several days until completely dry. Store in an envelope.
Cucumbers also require a fermentation process, but you do not have to ferment the seeds in a jar of water like the tomatoes. I have done that before, but I have also seen gardeners dry the cucumber seed as you would a squash seed.
Save the seeds from an overripe, yellow cucumber that has been left on the plant until it has doubled its picking size. This will allow the seeds to mature and triple their normal picking size.
In the picture here, there is one large cucumber on the left that is turning white and yellow--this means that the cucumber is mature enough to save seed from.
First, scrape out seeds into a sieve. Wash the seeds in the sieve over running water. Clean completely and dry on a paper towel or paper late for up to seven days.