Final answer:
The active growing stage of plants typically lasts a few months to many years, with larger trees taking several years to provide shade for undergrowth to develop.
Step-by-step explanation:
The active growing stage for most plants lasts for a few months to a few years, depending on the species and environmental conditions. In the context of a landscape recovering from an event such as a fire, for example, it can take many years for trees to grow large enough to provide the necessary shade that allows for smaller plants to start growing underneath.
This shade is crucial for the young plants as it protects them from the direct sun and helps maintain moisture in the soil, which are conditions that favor plant growth and development.