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Plant Guide

Brunswick

422 Bath Road
Brunswick, ME 04011
1-800-339-8111
207-442-8111

Falmouth

89 Foreside Road
Falmouth, ME 04105
1-800-244-3860
207-781-3860

Cumberland

201 Gray Rd (Route 100)
Cumberland, ME 04021
1-800-348-8498
207-829-5619

shrub

Gemo St. John's Wort

Hypericum kalmianum 'Gemo'

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Gemo St. John's Wort (Hypericum kalmianum 'Gemo') at Skillins Greenhouse

Gemo St. John's Wort flowers

Gemo St. John's Wort flowers

(Photo courtesy of NetPS Plant Finder)

Gemo St. John's Wort (Hypericum kalmianum 'Gemo') at Skillins Greenhouse

Gemo St. John's Wort in bloom

Gemo St. John's Wort in bloom

(Photo courtesy of NetPS Plant Finder)

Gemo St. John's Wort (Hypericum kalmianum 'Gemo') at Skillins Greenhouse

Gemo St. John's Wort fruit

Gemo St. John's Wort fruit

(Photo courtesy of NetPS Plant Finder)

Height:  30 inches

Spread:  3 feet

Sunlight:  full sun  partial shade 

Hardiness Zone:  4a

Other Names:  Kalm's St. John's Wort

Description:

Beautiful bright yellow buttercups flowers with bushy stamens; green leaves are narrow and willow-like; widely adaptable but thrives in moist, well-drained soil

Ornamental Features

Gemo St. John's Wort has masses of beautiful yellow buttercup flowers at the ends of the branches from mid summer to mid fall, which are most effective when planted in groupings. The flowers are excellent for cutting. It has green deciduous foliage. The narrow leaves do not develop any appreciable fall color.

Landscape Attributes

Gemo St. John's Wort is a multi-stemmed deciduous shrub with an upright spreading habit of growth. Its relatively fine texture sets it apart from other landscape plants with less refined foliage.

This shrub will require occasional maintenance and upkeep, and should only be pruned after flowering to avoid removing any of the current season's flowers. It has no significant negative characteristics.

Gemo St. John's Wort is recommended for the following landscape applications;

  • Mass Planting
  • General Garden Use
  • Groundcover
  • Naturalizing And Woodland Gardens
  • Container Planting

Planting & Growing

Gemo St. John's Wort will grow to be about 30 inches tall at maturity, with a spread of 3 feet. It tends to fill out right to the ground and therefore doesn't necessarily require facer plants in front. It grows at a medium rate, and under ideal conditions can be expected to live for approximately 5 years.

This shrub does best in full sun to partial shade. It is very adaptable to both dry and moist growing conditions, but will not tolerate any standing water. It is considered to be drought-tolerant, and thus makes an ideal choice for a low-water garden or xeriscape application. It is particular about its soil conditions, with a strong preference for rich, alkaline soils. It is highly tolerant of urban pollution and will even thrive in inner city environments. This is a selection of a native North American species. It can be propagated by division; however, as a cultivated variety, be aware that it may be subject to certain restrictions or prohibitions on propagation.

Gemo St. John's Wort makes a fine choice for the outdoor landscape, but it is also well-suited for use in outdoor pots and containers. With its upright habit of growth, it is best suited for use as a 'thriller' in the 'spiller-thriller-filler' container combination; plant it near the center of the pot, surrounded by smaller plants and those that spill over the edges. It is even sizeable enough that it can be grown alone in a suitable container. Note that when grown in a container, it may not perform exactly as indicated on the tag - this is to be expected. Also note that when growing plants in outdoor containers and baskets, they may require more frequent waterings than they would in the yard or garden.

 
 
Hardiness Zone Plant Height Minimum Sunlight Soil pH Preference
Characteristics
Massing  Garden  Groundcover  Naturalizing  Container 
Applications
Flowers  Winter Value 
Ornamental Features