Kalm’s St. John’s Wort

Description

Shrubby St. John’s wort is reasonably popular among native gardeners for a good reason – it’s an easy-going shrub that fills that niche where people want a yellow flowering shrub. It is loaded with flowers when it blooms, and you can get it to rebloom by deadheading it. It has a nice, round, tidy habit that does well in formal gardens and wild ones alike. It does lose its leaves in winter, but most are okay with winter looking like winter.

What if I told you that, albeit a near-native, there is a shrub that’s just like shrubby St. John’s wort, but evergreen? One that can also handle being wet (the former prefers dry sites)? One that is just as resilient and resistant to drought (though I guess then it looks like crap, but it’ll survive)?

Find Kalm’s St. John’s wort in the wild

This species is endemic to the Great Lakes region, and rare unless you live in Wisconsin or Michigan. If you haven’t heard of it, that may be why. That being said if you ever spend any time hanging out or camping on the Great Lakes, you may come across this species.

Habitats include interdunal swales, borders of small sandy ponds, moist to wet sandy meadows, and moist sand flats (pannes). Outside of Illinois, Kalm’s St. John’s Wort occurs on limestone flats (alvars). This shrub is found in high quality natural areas. It is also cultivated occasionally in gardens because of its showy flowers. (Source)

Grow Kalm’s St. John’s wort in your garden

You know this shrub gets hit with some serious lake-effect snow where it’s native. I have no idea if it is evergreen there (if you can even find it under the snow), but the cold winter we had last year didn’t bother it one bit. Site it similarly to the way you’d site shrubby St. John’s wort, though this one can tolerate more wet than Hypericum prolificum.

Additional information

Family

Container Size

Growth Cycle

Maximum Height

Maximum Width

Growth Rate

Lighting Requirements

Heliophily

7

Soil Moisture

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Wetland Indicator

FACW

Soil Texture

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Soil pH

acidic, acidic-neutral, neutral

Maintenance

I Will Survive

USDA Hardiness Zone

Ecoregion

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Native Habitat

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NatureServe Global Rank

NatureServe National Rank

NNR – not ranked in US

NatureServe State Rank

SNA – not applicable in PA

Sociability Index

level 3 – small patches

Bloom Color

Bloom Time

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Attracts

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Benefit To Habitat

caterpillar host, pollen, wildlife cover

Tolerates

deer tolerant, humidity, rabbits

Ornamental Features

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Ethnobotanical

medicinal

Garden Theme

pollinator garden, cottage garden, container garden, rain garden

Suggested Use

borders, container, hedge, mass planting, roadside ditch, small gardens, stormwater basin

Judgy Judy Factor

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