Mountain mint

Year-round

Pycnanthemum californicum, also called Sierra mint or California mountain mint, is a California native perennial in the mint family. It is not native to the Tallahassee area, but as a plant you already own it can still do well in a north Florida garden if you match it to moist, well drained soil and give it some relief from full afternoon sun.

• This plant is native to California, found wild in the Sierra Nevada, the Klamath and Coast Ranges, and southern California's Transverse and Peninsular Ranges. It is not native to Florida or the Southeast, so grow it as a garden perennial rather than a local wildlife-habitat pick.
• Give it part sun to full sun. Some afternoon shade helps it cope with Tallahassee's hotter, more humid summers than it sees in its native California mountains.
• Keep the soil consistently moist but well drained. In the wild it grows in moist mountain sites, so it does not like to dry out completely, but soggy soil that never drains can rot the roots.
• It grows roughly 2 to 4 feet tall and spreads by rhizomes like other mints. A border edge, buried barrier, or large container keeps it from wandering into nearby beds.
• Mountain mints are strong pollinator plants. This species is recorded supporting a wide range of native bees, butterflies, and moths.
• It is not on the ASPCA's toxic plant list for dogs or cats. The ASPCA does separately list common garden mint (Mentha) as toxic, so that is a different plant, but it is still worth watching a pet that likes to chew on new growth.

By late summer the spreading, minty growth can look a little loose. Keeping it edged or in a contained bed keeps the look HOA-conscious without losing the pollinator value.

Fall

Fall in Tallahassee is milder and drier than summer, with the first frost typically arriving in early to mid November, giving this plant a slow wind down toward dormancy.

• Once flowering tapers off in early fall, leave the seed heads standing for a few weeks. They keep drawing in late-season pollinators and look better left alone than cut hard right away.
• Stop feeding the plant by early fall so it is not pushing soft new growth right before the first frost.
• The Tallahassee area's first frost typically lands in early to mid November. Foliage will likely start to brown and die back not long after.
• Fall is a decent second window for dividing or transplanting, now that the worst summer heat has passed.

Winter

Tallahassee sits in USDA hardiness zone 9a with a mild winter for a plant that is used to cold at elevation in the California mountains, so expect this Sierra mint to die back to the ground after a freeze and come back in spring.

• Tallahassee is in USDA hardiness zone 9a. The first freeze typically lands in late November and the first hard freeze near the end of December.
• After a freeze browns the top growth, cut the dead stems back close to the ground. New shoots return from the base in spring.
• Keep winter soil on the well drained side. Cool, wet soil that does not drain is a bigger risk to the roots over winter than our mild cold snaps.
• No pruning is needed mid-winter beyond clearing dead stems. Wait for spring growth to show before shaping the plant further.

Spring

Spring in Tallahassee runs from around mid-March, when frost risk ends, into a warm and increasingly humid start to summer. This is when Sierra mint comes back from its winter dieback.

• Frost advisories in the Tallahassee area typically end around mid-March, so wait until then before counting on new growth to stay undamaged.
• Cut back any dead winter stems down to the fresh green shoots at the base. This tidies the plant and gives new growth room to fill in.
• Spring is a good window to divide a crowded clump or move new starts, before the heavier heat of late spring and summer sets in.
• Check soil moisture as temperatures climb. North Florida spring rain can be uneven, so make sure the ground is not drying out around new shoots.

Summer

Tallahassee summers are hot, humid, and rainy, and June through September is also this plant's bloom window, so its main show lines up with our heaviest afternoon storms.

• Expect white flowers with purple-spotted lower lips from June into September.
• Regular Tallahassee summer rain usually covers this plant's need for steady moisture. Water by hand only during a dry stretch of a week or more.
• High humidity raises the risk of powdery mildew on mountain mints. Give plants room to breathe and water the soil instead of the leaves to cut that risk down.
• Removing spent flower clusters can encourage more blooms and keeps the plant looking tidier through the season.