You can grow a fruit trees from a seed you collected from fruit you bought at a market, but be aware that the tree you grow may not produce fruit that is as large or as sweet as the fruit from which you took the seed. There's no way to know ahead of time just how strong or how sweet a tree grown from a seed is going to be. The good news is that growing a fruit tree from a seed is relatively easy, and it's something you can get started on right away. Try these steps for growing fruit trees from seeds such as apple, orange, lime and other seeds that do not have a large hard shell.
Place your fresh fruit seeds in one cup of weak tea mixed with 1/8 tsp. Epsom salts. Soak your seeds overnight.
Fill a growing tray with a mixture of 50% potting soil and 50% sphagnum moss. Dampen the mixture and allow it to drain so that it is damp but not soaking wet.
Poke 1/2-inch deep holes in the soil in your growing tray and drop a seed in each hole. Cover with the potting soil/sphagnum moss and dampen.
Place the tray in a warm location (70 to 80 degrees Fahrenheit) where it will get plenty of indirect sunlight. Keep the soil damp but do not soak.
Move the growing tray to a window with at least six hours of direct sun once the seeds sprout. Be sure to keep the soil moist.
Add 1/8 tsp. liquid iron chelate to a quart of water and use this mixture to water your trees once they sprout leaves.
Transplant your seedling to an 8-inch pot filled with 1/3 potting soil, 1/3 sphagnum moss and 1/3 garden soil when your tree is 6 inches tall. Leave in this pot until roots start to come out the drain hole. It is now time to plant outside in a sunny location.