Sweet Flag Care: Tips For Growing Sweet Flag Grass

calamus
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By Mary H. Dyer, Master Naturalist and Master Gardener

Japanese sweet flag (Acorus gramineus) is a striking little aquatic plant that tops out at about 12 inches. The plant may not be statuesque, but the golden-yellow grass provides plenty of bright color in soggy garden spots, along streams or pond edges, in semi-shady woodland gardens – or nearly any area where the plant’s moisture requirements are met. It is a good choice for stabilizing the soil in damp, erosion-prone soil. Read on for more information about Japanese sweet flag.

Arorus Sweet Flag Info

Japanese sweet flag, also known as Calamus, is native to Japan and China. It is a cooperative, slow-spreading plant that attains a width of 2 feet in about five years. Miniature greenish-yellow blooms appear on spikes in spring and early summer, followed by tiny red berries. The grassy leaves emit a sweet, rather spicy aroma when crushed or stepped on.

Sweet flag is hardy to USDA plant hardiness zones 6 through 9, although some Acorus sweet flag info indicates the plant is tough enough for zones 5 through 11.

Sweet Flag Care

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It doesn’t take much effort when growing sweet flag grass. Sweet flag plants tolerate light shade or full sun, although the plant benefits from afternoon shade in hot climates. However, full sun is best if the soil is extremely boggy.

Average soil is fine, but be sure the soil is consistently moist, as sweet flag doesn’t tolerate bone dry soil and may scorch. Similarly, the leaf tips may turn brown in periods of extreme cold.

To grow sweet flag in a pond or other standing water, place the plant in a container and set it in water less than 4 inches deep.

Sweet flag plant benefits from division in spring every three or four years. Plant the small divisions in pots and let them mature before transplanting them into their permanent locations. Otherwise, growing sweet flag grass is nearly effortless.

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