Either early spring or fall planting is suitable for date palms. If you'll be transplanting a tree rather than starting from seed, aim to plant on a day that isn't too windy. Otherwise ...
Most apple trees planted nowadays are grafted, but you can grow an apple tree from seed if you so desire. The main question ...
The Fire Date Seeds are a rare drop from the Fire Date Trees that you can gather from the ground. The Fire Dates appear in the game as small trees that grow on the lava that you can gather.