There are few really large seeds that are grown for indoors. Coconut and avocado are the exceptions.
The main advantage of large seed is that it is easy to handle, since it does not need mixing with sand or thinning out if too many seedlings germinate. In fact, large seeds can usually be sown into individual pots of soil large enough to support their growth for several weeks, eliminating the need to transplant the seedlings and risk them suffering a check in growth as a result of the shock.
Coconut is the largest seed grown for indoors, but as it is impractical to plant in the home, garden centers usually sell seed that has already been germinated. Avocado and date pits are good to experiment with, since they would otherwise be thrown away — there is nothing to lose by sowing them, and possibly a nice plant to gain. Both can be soaked in water first to maintain the moisture levels inside the seed if they cannot be sown immediately.
Be patient with larger seeds after sowing, because they may take some weeks to germinate. Keep the seed warm and the growing medium moist until the first shoot appears.
- Take an edible fruit and carefully slice it open with a clean, sharp knife. Ease the “pit” out of the middle with a teaspoon or blunt knife, being careful not to cut into it.
- Push the blunt end of the pit into a pot of soil, leaving the pointed end slightly exposed. Water to settle the soil, then keep warm at 65°F (18°C) until a shoot appears.