Many items from everyday living that would otherwise be thrown out and end up in a landfill some place be put to work in our home gardens. Some examples:
Cleaned plastic milk jugs can be reused as scoops, funnels, planters (just cut off the top 1/3, leaving the handle or not as you prefer), or mini-greenhouses (cut out the bottom and place over smaller plants, leave the cap on at night and remove it or the entire jug for the warmer days).
Seedling pots can be made from almost any plastic or plastic-coated cardboard container (milk cartons, yogurt containers, butter tubs, etc.). Just poke a few holes in the bottom for drainage and place in a waterproof tray or on the ground.
Leftover aluminum foil can be washed and smoothed out and used at the base of plants to repel aphids, flea beetles, squash vine borers, and other flying pests (they see the sky reflected in the foil and get confused as to which way is up and usually don't land). It can also be placed on walls to help protect the higher branches. The foil can also increase the amount of sunlight available to your plants. This effect is especially useful if you use the foil to line a seedling box, or make a reflective screen to put around your starting trays. Having light available from all sides helps prevent long, leggy growth and seedling lean. You can also use it to line your cold frame for the same reasons.
Cutworm collars can be made from almost any cylindrical object (bathroom tissue or paper towel rolls or even yogurt containers or small milk cartons) with the tops and bottoms removed. Just cut to 2" - 3" height and place around seed lings, putting at least one inch below the soil.
Large pieces of broken clay pots can be placed upside down in the garden to make inviting homes for pest-hungry toads and lizards.
Large paper bags and cardboard boxes of all sizes can be used to place over plants at night for frost protection. Be sure to remove as soon as the day warms up to let the sunshine in.
Smaller paper bags can be placed over ripening fruit or com to protect from frost, birds, or other pests. Cardboard boxes can also be used as windbreaks. Just remove the bottom and place top down around the plant. Let the top flaps rest flat on the ground and weight them down with rocks or soil to keep them from blowing away.
Use old wire coat hangers (snip off the hook and bend the rest into a "U" shape) as supports for agricultural fleece, shade cloth, or plastic to make a mini-greenhouse. Large plastic food bags can cover plants up to about a foot tall.
Banana peels can go into the compost pile, or buried around eggplant, peppers, roses, tomatoes, and other crops needing a potash or phosphorus boost.
Potato peelings or leftover salad greens can be used as traps in the garden for slugs, snails, grubs, cutworms, squash bugs, etc. (check under the piles every morning) before ultimately being composted.
Vine squash or melons trained to a trellis may need support for heavy fruit. Use old pantyhose, material strips or butter tubs to make slings to hold them up. Nylon stockings can also be used to store onions and garlic for the winter. Just drop one into the toe, tie a knot, drop another one in, tie another knot, etc. Hang where they will get good air circulation, and simply snip off as needed.
Metal cans (coffee, tuna, etc.) can be used in a variety of ways. Punch holes in the bottoms for seed starting; file the top edges and use cookie-cutter style to make perfect holes in plastic mulch for planting seeds; or use as watering gauges to measure sprinkler output. Be very careful if using as melon or squash slings, and use only in the shade as the cans can get very hot in the sun and injure the fruit. For the same reason, it is not a good idea to use the large size cans as frost or wind protectors. You could end up with COOKED VEGGIES!
Styrofoam egg cartons make excellent starting trays for small seeds; the cardboard ones^ absorb too much water unless you line them with something.
Wide-mouth jars can be filled 1/2 way with various solutions such as molasses, and buried to the neck in the garden to trap grasshoppers and other pests. They can also be hung in the trees to catch Codling moths and Japanese beetles. The narrow-necked bottles can be used to ward off rabbits, skunks, and other critters by filling part way with water, and buried at an angle with about four inches of the neck showing. The wind whistling through the opening makes an eerie sound. The 2 or 3 liter soda bottles can be used to make hummingbird feeders, or you can poke holes in them, and bury them next to your plants for a convenient water reservoir. By filling them you get the water right down to the roots and don't splash water on fungi-prone foliage (excellent for melons and squash!).
Recycle the kid's old toys: a small wagon can be used to transport heavy pots or bags of fertilizer, or serve as a seed starting tray. Old pinwheels, plastic snakes, lizards, birds, or frogs can help to scare away pests.
Strips of old material or nylons work great for tying up tomatoes and other climbers, and strips of foil or bright-colored cloth tied to a string around the garden can scare away vegetable-eating critters.
Use old tires as raised-bed planting areas, and recycle the wheel into a garden hose holder (just nail it to the side of the house).
Old tar paper can be used to mulch, or made into collars to deter root maggots.
Cut aluminum pie plates or TV dinner trays to make sturdy, weather-proof row markers. Use a ballpoint pen to permanently emboss the plant name on it. Snip one end to a point for ground insertion, or poke a hole to hang it on a plant. The pie plates can also be filled with beer or a yeast and water solution to make a time tested snail and slug trap. Large jar lids will work, too.
Utilize old fences or netting to make a trellis for your beans, peas, cukes, tomatoes, and even squash and small melons (see "slings").
And, of course, the ultimate recycling tool for the gardener is the compost pile. You can be as "scientific" as you want, or simply pile the stuff in and let it set for a year. You can use just about anything that comes available, except meat or dairy products and contaminated articles. Just cut or shred it as small as possible, and mix it up occasionally. If you don't have enough scraps for a true "pile", just bury it in the garden, and by next season nature will have broken it down into life-giving humus.