When you discover how easy it is to start plants from seed, you might be tempted to try starting fruit trees. Although many citrus and some other types of fruit propagate easily from seed, others aren't suited to this form of propagation. If you know that your fruit tree is an heirloom, or "old fashioned," variety, its seeds might be good contenders for new trees. But if it's a hybrid, don't expect the same exact fruit as the parent tree. Also, fruit trees you start from seed can take eight years--or more--to produce fruit, whereas young trees from the nursery will produce sooner.
Collect seeds from the tree you want to reproduce in fall for many types of fruit trees. Many citrus are ripe in the winter, so wait until you have very ripe fruit before you begin.
Eat the fruit away from the seed (or squeeze lemons), and then rinse the seeds thoroughly to remove any remaining pulp.
Spread seeds other than citrus on an old window screen or other porous material such as cheesecloth, and then place it in a dark, fairly warm, dry, well-ventilated area for seven to 10 days. If you're planning to use citrus seeds, you can start them right away, while they're still fresh and moist.
Combine one-fourth to one-half cup each of damp peat moss, Vermiculite and sand in a plastic bag and mix them well. Add several seeds to this mix and then seal the bag. Put the bag in your refrigerator to cold stratify the seeds for three to four months. There's a chance they might germinate in the refrigerator, so check your seeds every week and if they sprout, that's the time to pot them.
Fill pots or flats with half Vermiculite and half peat moss. Plant large seeds more deeply than small seeds and then cover them with more of your growing medium and water well. Try to maintain a temperature of around 70 degrees Fahrenheit and provide your pots with some direct sunlight, but make sure it's not too hot.
Move your pots to an area that receives more sun when your seedlings are two to three inches tall. You can also transplant seedlings into larger pots at this stage.
Fertilize your young trees with a standard houseplant fertilizer when they are about three months old. Feed them once a month after that, following your fertilizer's instructions.