Goldenrods

Goldenrods

Solidago Beyond the Roadside

By and Published November 28, 2022

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Goldenrod, the name conjures images of yellow-tinted roadside ditches extending for miles and for many the runny nose and watery eyes resulting from hay fever. Unfortunately for goldenrod (the genus Solidago), it is often erroneously blamed for the sniffles when it simply has the distinction of being the most visible flowering plant during the peak season for ragweed pollen shed—the ragweed is responsible, not the brilliant fields of goldenrod. For many traditional gardeners, the term goldenrod is synonymous with weeds. This is also unfortunate because only a handful of species are aggressively rhizomatous or seed into beds readily and give the whole genus an undeserved reputation. Many of us who first tried a goldenrod were disappointed by our choice because it became lanky and fell over as it grew in the rich soils of our garden beds.

This is a trait common to many of the weedier species and shared with the related “asters.” This is a remarkably diverse genus, there are at least 65 taxa in the Carolinas alone! They are mostly unified by having small involucrate heads of golden yellow ray and disk flowers golden (though a few are bicolored or white) clustered in attractive wands, raceme-like or more flat-topped arrangements. Most of the species prefer open, sunny locations but a few are well-adapted to the woodland garden. Many are amazing plants very worthy of cultivation and incredibly important to insects and other wildlife and we shouldn’t judge the entire genus based solely on the common Tall Goldenrod (Solidago altissima). Perhaps the best way to start talking about the genus is by talking about what to avoid based on our experience.

Goldenrod Problems and How to Avoid Them

Solidago altissima (Tall Goldenrod) and Solidago canadensis (Canada Goldenrod). While these plants may make a colorful mass along the roadside or in old fields, they are far too aggressive and difficult to eradicate in most gardens. These plants are so problematic that they often invade meadow gardens or prairie “restoration” projects to the detriment of even the most pugnacious of native grasses. In ruderal (unkempt and disturbed) areas they are wonderful pollinator plants and can serve as a refugia for hosting beneficial predatory insects. Additionally, these plants can even attract woodpeckers! Yes, that may sound crazy, but I’ve seen many a Downy Woodpecker picking at the galls where wasp larvae are developing in the dead winter stems of Tall Goldenrod. Bottom line: if you have them in a field or weedy area great, just keep them out of designed garden space.

Solidago rugosa (Wrinkle-leaf Goldenrod). Most forms of this species will also quickly fill garden space because of their aggressively rhizomatous habit. There are exceptions to this rule (see Solidago rugosa var. celtidifolia ‘Fireworks’).

While goldenrods are generally pest free and fairly resistant to herbivory by deer and rabbits, they are prone to lace bug infestations. Lace bugs are fascinating and intricate tiny true bugs that can best be described as looking like a tiny alien. While they’re cool to look at, they can form infestations on the undersides of leaves where they suck nutrients from the plant forming pale discolored patches on the upper surface of the leaf. While these insects generally don’t harm the plant to the point that it dies, they do considerably reduce the attractiveness of plants in the Aster family. Fortunately, they are not difficult to control. A simple Neem oil or horticulture oil treatment, starting in April when the lace bugs first become active can help to reduce them throughout the season. Additional treatments can be applied as lace bugs are noticed.

When to Prune Goldenrod

I have always tended to cut back my tall asters and goldenrods in mid-May, leaving about 4” of stem at the base to encourage them to branch and bush out to form a smaller and more compact form that is less likely to flop over with age. Many of our beloved asters and goldenrods grow in impoverished soils and when they are offered circumneutral, rich soils in our gardens they greatly exceed their natural size and form. This simple trick will keep species like Seaside Goldenrod and Georgia Aster at a much more manageable height and form. I would suggest planting your desired species and observing it for the first year. If it grows far too lanky, don’t throw it out, next year cut it back in May. I also suggest going light or avoiding the fertilizer at all on these plants.

The Best Goldenrod Plants for Your Garden

Solidago caesia (Axillary Goldenrod) and Solidago curtisii (Curtis’s Goldenrod) These two species are very similar and both of great use in the woodland garden to bring a bright golden light into the often tired and dark corners of shade. Both will perform well in part shade to high shade (resist planting them under a Rhododendron). They spread slowly via rhizomes to form small masses that are topped with 12-30” tall stems with short golden branches of inflorescences lining the stem like a golden wand. Axillary Goldenrod is widespread in the eastern United States but not common in the mountains while Curtis’s Goldenrod is mostly confined to the Appalachian region. Axillary Goldenrod is a good example of a plant that you will see growing on slopes in the woodlands of the Piedmont that never looks great but looks much better when given the care and rich soil of our gardens. (Hardiness Zone 5a-8b)

Solidago 'Hiddigeigei' (Hiddigeigei Goldenrod) A stunning goldenrod, grown for its screaming yellow foliage as it emerges in early spring. This form was discovered in a garden in Berlin and was introduced and named by Christian Kress of Sarastro Nursery after a bright-eyed tomcat in a Viktor von Scheffel novel. The foliage on this tight clumper ages to green with the onset of warm weather. Solidago 'Hiddigeigei' has behaved exceptionally well in our garden trials, forming a tight clump with no seeding. So far, we have been unable to assign this to any species. This is truly a Goldenrod with two capital G's.

Solidago mexicana ‘Endless Stares’ (Endless Stares Southern Seaside Goldenrod) 'Endless Stares' is a 2024 Plant Delights/JLBG introduction of an amazing Patrick McMillan collection of Solidago mexicana from Beaufort County, South Carolina. This probably tetraploid form of a tightly clumping species that naturally occurs in coastal dunes and marshes from Maryland to Mexico, skyrockets from spring through summer, when the deep purple stems top out at 8' tall. The stems are very rigid and are a perfect complement to the narrow clusters of deep golden flowers that are produced in October (NC). Try planting this species among or near other rigid vegetation that will support the very elongate stems during windy weather or alternatively, a simple cutback to 4-6” from ground level in May will produce a more branched specimen. A perfect bold upright architecture to bring a dramatic impact and dimensionality to larger beds. (Hardiness Zone 6a-9b)

Solidago rigida (Midwestern Bold Goldenrod) This can be one of the most attractive additions to the late summer/early autumn garden. Bold is a good descriptor as this tightly clumping species produces 12-30” tall stems with clusters of bold golden flowers in a rather flat-topped arrangement that is often swarming with bees, wasps, beetles, and small butterflies. Its polite manners in the garden and superb form make this one of the better choices for most gardeners. It is naturally found in tallgrass prairie systems and extends its range from the Midwest into North and South Carolina, AL, and MS where prairies once were. A southern form with smooth leaves and stems is now recognized as Solidago jacksonii (Southeastern Bold Goldenrod) and displays all the good traits of its more northern cousin--or maybe the northern cousin learned good manners from it? (Hardiness Zone 4a-8b, at least)

Solidago rugosa var. celtidifolia ‘Fireworks’ (‘Fireworks’ Goldenrod) 'Fireworks' is a 1993 introduction from retired NC Botanical Gardens' Ken Moore that has withstood the test of time and is still regarded as the top goldenrod of all time. Originally selected from a population in the NC Coastal Plain, 'Fireworks' was rated #1 in the goldenrod trials at the Chicago Botanic Garden. From a slowly spreading rhizome, the stalks emerge upward in late spring, topping out at 3' tall. In mid-August in NC, the clumps are showered with 18" long arching spires of brilliant yellow flowers held well atop the foliage...attracting nearly every pollinator you can imagine. The flowers resemble fireworks or literally “bombs bursting in air.” This is one of the finest additions to the fall garden! Native bees and wasps will thank you for such a great pollinator plant. (Hardiness Zone 7-10)

Solidago sempervirens (Northern Seaside Goldenrod) This attractive goldenrod is native to maritime habitats and the edges of salt marshes from the outer banks of North Carolina. The northern variation of seaside goldenrod (as compared to S. mexicana) is a much shorter plant with arching stems reaching 30” in height. Like its southern cousin it is a clumping species that doesn’t spread aggressively in the garden. The basal leaves form an attractive tuft prior to flowering. Our plants are from Maine and Martha’s Vineyard and despite these strongly northern roots performs quite well in common garden conditions here in the South. (Hardiness Zone 5a-8a, at least)

Solidago shortii ‘Solar Cascade’ (Solar Cascade Goldenrod) ‘Solar Cascade’ is a Cincinnati Zoo and Botanical Garden selection of the federally endangered Solidago shortii, naturally found in only a few small populations in Indiana and adjacent Kentucky. Solidago shortii has short rhizomes and slowly expands to form sizeable patches in the garden. In the wild, it is found on alkaline clay slopes but is well-adapted to most garden conditions. The 30" tall stalks are topped from late August through October with showy panicles of gold. (Hardiness Zone 5a-8b, at least)

Solidago sphacelata ‘Golden Fleece’ (Golden Fleece Autumn Goldenrod) Dr. Dick Lighty, former director at Delaware's Mt. Cuba Center, first saw this Solidago on a flashlight walk one evening after giving a garden talk. From a modest beginning, this spectacular selection of the East Coast native goldenrod (Illinois south to Mississippi) has found its way into the finest gardens of England and Europe. The round basal leaves of Solidago 'Golden Fleece' give rise to multi-branched, 20" long, arching spikes adorned with tiny clusters of golden-yellow flowers starting in early September. Our 10-year-old clumps of Solidago 'Golden Fleece' are now just over 3' wide. This is a very easy-to-grow and wonderfully drought-tolerant plant. It reaches its best development in part sun but will tolerate considerable shade or full sun. (Hardiness Zone 4a-9b)

Solidago sp. nov. ‘Montana Minnie’ (Montana Minnie Goldenrod) Honey, I shrunk the goldenrod! Solidago 'Montana Minnie' is a 2023 Plant Delights/JLBG introduction of a fascinating new miniature goldenrod, discovered in 2015 by plantsman Dr. Patrick McMillan and his son Nic in Phillips County, Montana. While you would expect this plant would grow in rocky crags of the highest peaks, we found this in a low elevation swale of sandy soil growing among Sand Reed Grass in the vast prairies of eastern Montana. This fascinating rock garden-sized goldenrod tops out at a whopping 3" tall with short spikes of yellow, starting for us in late spring. It is slowly stoloniferous but plays well with others. Despite its northern roots it tolerates the heat of the Carolina summer with ease. (Hardiness Zone 4a-8a)

Solidago virgata (Wand Goldenrod) This great US native is a garden designer's dream. Wand goldenrod is native from NC to LA, where it occurs in Longleaf Pine savannas, flatwoods, and other damp sandy locations. The cool thing about Solidago virgata is when it starts to expand from its winter basal rosette, the leaves along the flowering stem are tightly adpressed (disguised by lying flat against the stem). These stems expand all spring and summer, appearing like a colony of skinny snakes being lured upward by a magic flute. Starting in October, the top 10" of the "snake" turns to bright yellow as the flowers open—a delight to pollinators. Wand Goldenrod is densely clumping and is at home as a companion to your pitcher plants in a bog garden but also performs well in standard garden conditions if not allowed to dry out for extended periods. (Hardiness Zone 6b-10, at least).

 

 

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