When one bulb matures it produces other bulbs in it’s space changing a single bloom one year to multiple blooms in following years. Side note: I would plant Daffodil bulbs instead of Tulips because the critters did not dig and eat those bulbs. Copyright 2019 Pamela BreitbergDaffodils tend to populate themselves in a garden, also known as naturalizing. This cluster is an example of one bulb becoming multiple within one space. Copyright 2019 Pamela Breitberg