Answer: If you are thinking of a "clump" with all three growing very close together, simply dig a single hole wide enough for all three root systems and plant them in it together. Most "clump birches" are started this way at the nursery. If you are thinking of a naturalized grove, such as we would see in the wild, set them at uneven distances apart to avoid making an identifiable pattern. The minimum and maximum distances would be determined by the space available, but since white paper birch (Betula papyrifera) grow to be very large trees I would suggest at least 15 to 20 feet or more.
Q&A Library Searching Tips