The lovely—yet poisonous—bog rosemary, Andromeda polifolia, is a small evergreen shrub that is usually found in marshy conditions. It features blue-green leaves and clusters of pink or white blossoms. This plant usually takes a lot of watering. It should be planted in wet or moist areas, hence the name "bog" rosemary. During dry periods or droughts, you should water often.
Bog Rosemary is poisonous because of andromedotoxin, also known as grayanotoxin, found in all parts of the plant. Take this into careful consideration when deciding to grow this shrub at your home, especially if you have pets or children. If ingested, the poison in the shrub can lower blood pressure and may cause respiratory problems, dizziness, vomiting, or diarrhea.
Naming Bog Rosemary
Commonly called bog rosemary, it may also be known as marsh andromeda. It was named by Swedish botanist Carl Linnaeus during his 1732 expedition to Lapland, Finland, and compared the plant to Andromeda from Greek Mythology. The species name, polifolia means "gray-leaved" in Latin. It belongs to the Ericaceae family. It is not a true rosemary (Rosmarinus), as those species are a part of the Lamiaceae, or mint, family.
Where Bog Rosemary Trees Grow
The U.S. Department of Agriculture established the standard by which gardeners and growers can determine which plants are most likely to thrive at a location. This is known as the USDA Plant Hardiness Zone Map. Accordingly, this plant should be planted in zones 2 to 6 for best results, which encompasses the bogs and cold-peat areas in northern and central regions of the U.S. It is a native plant in North America, Europe, and Asia.
Bog rosemary will reach a mature size of 1 to 2 feet tall and wide, creating a rounded shape. Bog rosemary can be planted in full sun or partial shade.
The blue-green evergreen leaves are quite like those of rosemary plants. The urn-shaped flowers are typical of the family and are formed into clusters. They can be either white or pink. The tree usually flowers in late spring to early summer. Small brown capsules form once the flowers are pollinated — the fruit, this small capsule, containing numerous seeds.
Notable cultivars of bog rosemary include "macrophylla" and '"compacta," which have both received the Award of Garden Merit from the Royal Horticultural Society. "Blue Ice" has a strong bluish tone in the leaves. "Nana" is a dwarf version.
Tips for Growing
Bog rosemary is a typical ericaceous plant. Like other ericaceous plants, such as azaleas, blueberries, and heather, bog rosemary requires acidic soil to succeed. After first planting, you might layer the soil with two inches of peat moss or pine needles to discourage weeds and retain moisture.
Your shrub will likely not need to be pruned except to remove parts that have become dead, diseased, or damaged.
In most cases, Andromeda polifolia does not suffer from any major pest or disease problems. Its poisonous properties seem to protect it from usual pests that can affect bog flora.