Reading Comprehension

Read the passage and answer the question.

The color of a hydrangea's flowers can change depending on the soil it grows in. In acidic soils, the plants take up aluminum more easily, and this produces blue blossoms. In more alkaline soils, the aluminum becomes locked away and unavailable, so the flowers turn pink instead. Gardeners who want to shift the color can adjust the soil's chemistry, adding certain materials to make it more acidic or more alkaline. The change is not instant, however; it may take a full growing season or longer before the new color fully appears in the blooms.