A member of the Japanese Astilbe plant family, red sentinel is a species characterized by early blooms and red tinged, glossy green leaves. The flowers of the red sentinel appear in early summer and grow in dense clusters that resemble pyramids. They grow well as a container or patio plant, and will thrive in semi-shady woodland areas.
Red sentinel needs to be planted in fertile soil. Healthy, fertile soil is rich in nitrogen, phosphorus, and potassium. Healthy soil can be found where other types of plants have been grown and then died of natural causes, depositing organic matter like dead leaves into the soil. If you plan to plant your sentinel flower in a new garden area, or in a location where the soil is dry or clay, you will need to fertilize the soil at the time of planting, in late spring before any flowering starts.
Astilbe sentinels are hardy, long-living perennials that grow best in light shade to filtered sun. Plant your sentinel flower in a location where it will be sure to receive around four hours, but no more than six hours, of direct sun each day. Sentinels will grow when planted in full shade, but they will not bloom as abundantly. Consistent watering is the main requirement. Dryness can quickly mean the end of this plant, especially if planted in a location where it receives lots of direct sunlight. Give your sentinel a good drink of water each day, and check the soil daily to make sure it stays nice and moist. When the plant has become dormant for the season, leave the old foliage on until the next spring. The old, dead foliage will help protect the plant against winter damage, and the fallen debris serves as an excellent organic soil fertilizer. Red sentinel grows best when planted in the USDA hardiness zones 4 through 9.
Pest and Disease Tips
Red sentinel flowers are hardy plants that are deer and rabbit resistant. They do, however, tend to be prone to powdery mildew. Powdery mildew is a fungus that looks like a white or gray powdery growth on the leaves, stems, or flowers of the plant. This disease does little to affect the health of your sentinel plant, but can make it look unsightly. If this is a concern, treat the plant with a fungicide according to label directions.