Set the Plants
Once you have created your riverbed, you can place the rest of your plants. Work down the landscape and play around with plant arrangement. You want to mix plant textures. Add colorful flowers, but make sure to spread them out so that the look is natural. Lay the plants out in their containers, make adjustments and then begin to set them (Image 1).
Take your time when setting your plants and flowers. Occasionally step back and observe your work, making sure you have not grouped too many of the same flowers or plants together.
If you decide to use plants that come in a container, take them out of the container first, and then scratch the sides of the soil to loosen the roots (Image 2). You want to expose some of the fibrous material so that once they are set they can take in water faster.
Set the plants in holes that are twice as wide as the plant's roots. Do not make the hole too deep. The top of the plant should stick out of the ground about a quarter of an inch (Image 3). Eventually, when you add mulch, the feeder roots at the top of the plant will get water immediately.
Some of the plants you choose may come covered in burlap. As you set it, peel it away from the root, but it is recommended to not remove the whole piece of burlap. It is holding the root ball in place, and removing it entirely puts the plant at risk of having the roots break apart.