Don't throw away those old seed packets. Despite having passed their expiration date, it is still possible for at least a percentage of the seeds to germinate under the right conditions. 2,000-year-old dates and a 1,300-year-old Chinese lotus, whose ages were verified by radiocarbon dating, are the oldest seeds ever known to produce viable plants. The dates were found in 1973 in the ruins of Masada. Desert agriculture expert Elaine Solowey's decision to soak them until they would absorb water and enzymatic fertilizers restored the date seeds to viability.
Spread seed on a dry sheet of white paper. Sort out the largest, best-looking seeds to attempt to germinate.
Lay a paper towel on a plate or in a shallow bowl. Spread seeds in a single, even layer and top with a second paper towel.
Mix the nutrient solution first, in a 30-gallon plastic barrel or storage bin. Combine 25 gallons cool water with 1/2 oz. potassium phosphate, 2 oz. potassium nitrate, 3 oz. calcium nitrate and 1.5 oz. magnesium sulfate.
Mix the micro-nutrient solution separately in a 1-gallon plastic jug by combining 1 gallon cool water with 2 tsp. boric acid, 1 tsp. manganese chloride, 2 tsp. zinc sulfate, 1 tsp. copper sulfate and 4 tsp. iron sulfate.
Pour the micro-nutrient solution into the 30-gallon container of nutrient solution. This solution was developed by Dennis R. Hoagland in 1944 and is still used in hydroponic gardening to ensure that plants receive adequate amounts of trace elements essential to plant growth.
Pour 1/4 cup of the resulting mixture over the covered seeds. Place the plate or bowl in a warm, dark place until the seed cases split and show the tail of a newly formed plant. Sort through the split seeds for those with a long, healthy-looking tail. Compost the remaining sprouts.
Place the healthiest-looking sprouts in a window with a southern exposure and allow them to continue to sprout until a leaf begins to form. Keep them soaked in the solution until the first leaf appears.
Select the healthiest of the seedlings and compost the remainder. Poke a hole in the bottom of each used beverage cup. Place a broken piece of clay pot in the bottom of each cup. Fill 1 inch deep with glass marbles or river rocks.
Fill cup with 2 to 3 inches of shredded paper and finish filling the cup with aged compost or worm castings to within 1.5 inches from the top edge.
Check your seed packet to determine the correct planting depth for your seeds. Use the eraser end of a pencil to create 3 to 6 holes in the soil in each cup. Place one seedling in each hole, with any leaves or other green portions above the soil surface. Water daily as directed on your seed packet, using the nutrient solution.
Transplant seedlings outdoors after all danger of frost has passed. If you have any remaining nutrient solution, continue to use it daily until it is gone. To transplant, break the sides of the cup in three places. Dig a hole the same depth as the height of the cup, with the same diameter. Place the cup in the hole and pull soil around it.
Mulch in a ring around each plant using shredded paper, straw or lawn clippings, making sure that the mulch does not touch the plant.