Plant of the Month – October, 2007

Acorus gramineus

Latin name: Acorus gramineus
Common name: Sweet Flag
Flowers: Not Showy
Foliage: Green variegated with white or yellow
Mature height: 3 inches to 1 foot, depending on variety
Hardiness: Perennial to Zone 6
Soil: Regular garden or standing water
Exposure: Shade to full sun
Water usage: Medium
Sources: Mail-order, internet, or local nurseries

I realize that this installment of “plant of the month” doesn’t have showy flowers and isn’t one of the flashiest plants I’ve showcased, but it is tough! Variegated sweet flag is indispensable for adding interest to shady areas. The evergreen, upright foliage goes perfectly with wood fern (Theylpteris kunthii) and both like the same conditions. Sweet flag will grow equally well in full sun, as long as it is kept evenly moist.

My favorite way to showcase this plant is in containers. The fast-growing clumps of arching foliage look great combined with other flowers in pots. Also, if you have a container you love that doesn’t have a drainage hole, then this is the perfect plant. Acorus is native to edges of streams and bogs and flourishes in saturated soils. Diseases and insects are seldom problems with acorus.

There are several varieties of sweet flag available, but my favorite two are ‘Ogon,’ a 12-inch-tall variety with yellow-variegated leaves, and ‘Variegatus,’ with white variegation. There is also a dwarf form, A. gramineus ‘Minimus Aureus,’ that gets only 3 inches tall.

So if your garden is looking a little bare this winter, sweeten it up with a little sweet flag. You can see all of these varieties planted at the Dallas Arboretum Main Trial Gardens. We are located at 8525 Garland Road, overlooking White Rock Lake. For more information, visit

About the author: Jimmy Turner is the Director of Horticulture Research at the Dallas Arboretum. For more plant profiles by Jimmy, subscribe to Neil Sperry’s GARDENS Magazine.

Posted by Neil Sperry
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