Heart-leaf Golden Alexanders

Year-round

Heart-leaved golden alexanders is confirmed native to New York State, including the New York City area, and is an easy native perennial that also hosts black swallowtail caterpillars.

• This plant is confirmed native to New York. The New York Flora Atlas lists it as present and apparently secure (state rank S4), including records in Kings, Queens, Richmond, Nassau, and Suffolk counties.
• The Lady Bird Johnson Wildflower Center also places New York within its native range, describing the range as running from New York west to Ohio, Wisconsin, and Manitoba.
• It is a caterpillar host plant for the black swallowtail butterfly, confirmed by the Missouri Botanical Garden.
• It grows in tidy, non-spreading clumps about 1 to 2 feet tall, which keeps it easy to fit into a small city or suburban bed.

Its compact clumping habit and clear spring bloom period read as a deliberate planting rather than a weed, which helps it fit an HOA-conscious front yard.

Fall

Fall in the NYC area is mild and stretches out, giving plenty of time to plant, divide, or collect seed before the ground gets cold.

• The average first fall frost in the city and immediate coastal areas often does not arrive until mid to late November, so there is a long window for fall planting.
• Collect ripe brown seed heads in September if you want to save or share seed before they shatter.
• This is a good time to divide a crowded clump, since cooler weather reduces stress on the transplant.
• The plant goes dormant on its own once the days shorten, so there is no urgent fall task required for its health.

Standing dead stems over winter can look untidy for an HOA-conscious front yard, so many gardeners cut them back to about 6 inches in late fall for a neater look.

Winter

Winters in the NYC area are milder than farther inland, and this plant is far hardier than it needs to be for the local cold.

• This species is hardy to USDA zone 3, well beyond the city's zone 7a to 7b, so it comes through a typical local winter without any protection.
• No mulching or wrapping is necessary. Ordinary local winter cold is not a concern for an established plant.
• If old stems were left standing, they can shelter overwintering insects through the cooler months.
• Late winter is a good time to clear matted leaves before new growth starts, usually by mid to late March in the city.

Spring

In the New York City area, this plant blooms earlier than it does farther north, generally lining up with the mild local spring.

• Expect flowers from mid April into May in the NYC area, earlier than in colder parts of its range, based on growing notes from NC State Extension and Prairie Moon Nursery.
• The average last spring frost in the city itself lands in early to mid April, so new growth is rarely at risk from a late freeze.
• Clear away winter debris by late March so the crown gets sun and can start growing.
• Skip the fertilizer. This plant is used to average soil and heavy feeding just makes it flop over.

Summer

Summers in the city and on Long Island are warm and can be dry, and this plant handles that stretch with little help once it is established.

• By July the flowers are done and seed heads form. Leaving them up lets the plant reseed and gives birds something to eat.
• This plant tolerates dry spells well once established, so it usually does not need extra watering during a typical NYC-area summer.
• If you see caterpillars eating the leaves, they are likely black swallowtail caterpillars using the plant as a host, confirmed by the Missouri Botanical Garden. Leave them be.
• Deadheading is optional and mainly a matter of tidiness, since the plant will not rebloom after its main flush.

Year-round

Year-round care for heart-leaf golden alexanders around Binghamton, NY: sun to part shade, moist sandy to sandy clay soil.

• Give it sun, part shade or shade.
• It prefers moist sandy or sandy clay soil and tolerates alkaline conditions.
• Plants reach about 1 to 3 feet tall.
• Small yellow flowers open in May and June.
• It is a short-lived perennial. Divide mature plants in spring or fall.

A compact clump with a clear spring bloom period reads as a planned bed perennial.

Year-round

Heart-leaved golden alexanders is confirmed native to Wisconsin and is an easy, low-care native perennial for Milwaukee-area yards. It also serves as a caterpillar host plant for the black swallowtail butterfly.

• This plant is confirmed native to Wisconsin. Its native range runs from New York west through Ohio and Wisconsin into Manitoba and British Columbia, based on the Lady Bird Johnson Wildflower Center and the USDA PLANTS Database.
• It is a caterpillar host plant for the black swallowtail butterfly, confirmed by the Missouri Botanical Garden.
• It grows in tidy, non-spreading clumps about 1 to 2 feet tall, which keeps it easy to fit into a small bed.
• It handles both moist and dry soil once established and tolerates full sun to light shade.

Its tidy clumping habit and clear spring bloom period read as a deliberate planting rather than a weed, which helps it fit an HOA-conscious front yard.

Fall

Fall in the Milwaukee area is a good time to plant new starts or collect seed, and this plant needs only light cleanup before winter.

• The average first fall frost in the Milwaukee area lands in early to mid October, which gives seedlings planted in September several weeks to root in before it turns cold.
• If you want to collect seed, gather the dry brown seed heads in September before they shatter and scatter on their own.
• This is a good window to divide a crowded clump, since the plant is done blooming and root growth is still active before the ground freezes.
• Cutting the plant back in fall is optional for its health. It goes fully dormant on its own either way in a Wisconsin winter.

Standing dead stems can look untidy to an HOA over winter, so many gardeners cut them back to about 6 inches in late fall for a tidier look, even though the plant does not need it.

Winter

This plant is fully dormant and cold-hardy through a Milwaukee winter and needs no protection.

• This species is hardy to USDA zone 3, well beyond Milwaukee's zone 5b to 6a, so normal winter cold will not harm it, based on Prairie Moon Nursery's hardiness rating.
• No mulching or wrapping is needed. Snow cover is usually enough insulation for the roots.
• If old stems were left standing, this is when they shelter overwintering insects, including any swallowtail chrysalises that may have formed nearby.
• Once snow melts in late winter, rake off matted leaves before new growth starts.

Spring

In the Milwaukee area, this plant wakes up and blooms a bit later than it does farther south, right around when the last spring frost is wrapping up.

• Expect flowers from about mid May into June in the Milwaukee area, based on growing notes from Prairie Moon Nursery for this species.
• New shoots handle a late cold snap fine, so there is no need to cover the plant if a frost is forecast after it comes up.
• Clear away winter mulch or old leaf litter by mid April so the crown can warm up and get moving.
• Skip the fertilizer. Rich soil can make the stems grow tall and floppy instead of staying sturdy.

Summer

Once it has finished blooming, this plant needs very little from a Milwaukee gardener through the summer heat.

• By July the flowers fade and seed heads form. You can leave them standing. They feed birds and let the plant reseed itself.
• This plant tolerates the dry stretches common in southeastern Wisconsin summers once it is established, so extra watering usually is not needed.
• If you see caterpillars eating the leaves, they are likely black swallowtail caterpillars using the plant as a host, confirmed by the Missouri Botanical Garden. Leave them alone.
• Deadheading is optional. It will not produce a second flush of bloom, so cutting back spent flowers mainly helps the bed look neater.