One way to ensure you spend more of your gardening time in your actual garden is to make the most of what you have on hand. After four to six weeks, your hydrangea should have sprouted roots and be ready to transition to your garden. To do this, find a low-hanging branch on your hydrangea plant. Remove all the leaves from one of its leaf clusters and poke the bare stem into a container of potting soil. Hydrangeas are one of the most common garden plants, and they're fairly easy to care for.