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Goldenrods deserve a place in your garden

A version of this article originally appeared in 2 Million Blossoms quarterly

Autumn in New England: crisp mornings, apple cider, and county fairs. Thriving in the background of this scene—overlooked, but ubiquitous—are goldenrods, their luminous yellow spires brightening tired roadways, fields, and woodlands.

Goldenrods (Solidago, Euthamia, and Oligoneuron spp.) are a group of 100+ species of asters native to North America. All are pollinator powerhouses. They bloom in succession from June through October, providing sustenance and shelter for pollinating insects long after the flower-laden days of summer have passed.

Yet, goldenrod gets a bad rep, mainly because of two pervasive beliefs. First, that goldenrods cause hay fever and second, that goldenrods are hard to control in the garden. The first is a myth–goldenrods don’t cause allergies–and the second fails to recognize that while some goldenrods are unkempt, most are well behaved. In both cases, disdain is unwarranted, so I’m here to make the case that goldenrods deserve a place in your garden.

Goldenrods are beautiful and ecologically important additions to any garden.

A case of mistaken identity

Goldenrods can’t make you sneeze. They are animal-pollinated, meaning their pollen is can carried by insects, not the wind. The real culprit of hay fever is ragweed pollen, which is dry and easily picked up by a breeze, tickling our sinuses and making us sneeze. The two plants grow in similar open habitats and flower in fall, but ragweed produces green, nectarless flowers, which are never attractive to insects.

Although goldenrods also get a bad reputation for being unruly, only some species are unfit for gardens. Canada goldenrod (Solidago candensis), giant goldenrod (Solidago altissima), and grass-leaved goldenrod (Euthamia graminifolia) are indeed quick to colonize open areas and, once established, sprawl unchecked via wind-dispersed seeds and underground rhizomes. These species should be avoided in backyard gardens, but are suitable for large meadow plantings, rain gardens, or roadside restorations.

Goldenrods for your garden

For every goldenrod species that’s weedy, however, there’s at least one that’s tidy. Take blue-stemmed goldenrod (Solidago caesia) and zig-zag goldenrod (Solidago flexicaullis) that spread slowly in shade and partial sun. Or showy goldenrod (Solidago speciosa) and stiff goldenrod (Oligoneruon rigida) that form elegant clumps in well-draining soil. Planting along a salted roadway? Look no further than seaside goldenrod (Solidago sempervirens) which is tolerant of salt since it naturally grows along coastlines. And if you already have too many yellow flowers in your fall garden, add contrast with the cream-white blooms of silverrod (Solidago bicolor).

Many goldenrod cultivars have tidy growth habits, too, but not all provide high quality resources for pollinators. One cultivar that does is wrinkleleaf goldenrod ‘Fireworks.’ Pollinators love it and, true to its name, it adds a pop of color, texture and intrigue to any planting.

To help you select the perfect species for your planting, I’ve collated a list of goldenrod species native to the eastern US that are also available in the horticulture trade.

Insect Magnet

By planting goldenrods, you support late-season insect pollinators—bees, beetles, butterflies, moths, and wasps—that depend on it. Goldenrods feed many specialist bees, like hairy-banded mining bees (Andrena hirticincta) and spine-shouldered cellophane bees (Colletes simulans), that use goldenrod pollen to complete their life cycles. Queen bumble bees and honey bees, too, feed on goldenrod nectar to build up fat reserves before winter.

Hairy-banded mining bees (*Andrena hirticincta*) are common visitors to goldenrod flowers. By planting goldenrod you help these specialist bees complete their life cycles.

Beetles also find meals on goldenrod. Locust borers consume the protein-rich pollen whereas goldenrod soldier beetles snack on aphids. Blister beetles drink nectar, but also deposit eggs on the flowers. Once hatched, blister beetle larvae catch a ride on a solitary bee back to her nest. There, they disembark, kill the bee offspring, and develop on the pollen provisions.

Goldenrods support more butterflies and moths than any other perennial forb: 115 species of Lepidoptera eat goldenrod leaves and shoots. Countless flies, grasshoppers, thrips, and true bugs (e.g. aphids and stink bugs) devour goldenrod as well, meaning individual plants teem with insect life.

Yellow-collared scape moths (Cisseps fulvicollis) can often be seen nectaring on goldenrod flowers.

This menu of tasty insects attracts wasps. Predatory wasps, like paper wasps and potter wasps, hunt vulnerable, soft-bodied insects on goldenrod. While planning their next attack, they refuel on nectar and rest on stems. (Don’t worry, these solitary wasps are harmless to people!)

Fraternal potter wasps (*Eumenes fraternus*) may look fierce, but they are harmless to people. These wasps are common visitors to goldenrods where they feed on nectar and hunt for soft-bodied insects to bring back to the nest.

Parasitic wasps take advantage of this abundance of prey in a different way. They lay eggs, and their larvae subsequently develop, in the homes of other insects. Some parasitic wasps lay eggs in goldenrod galls, which are swollen stems containing a fly larva. Others only use goldenrods for nectar and deposit their eggs into the nearby nests of solitary bees.

Other animals, too, are drawn to goldenrod. Ambush bugs, for example, make a tasty snacks of nectaring insects.

Importantly, patches of goldenrod provide relief for insects on the move. Adult monarch and painted lady butterflies rely on goldenrod nectar during their annual migrations. Occasionally, they’ll spend cool nights hanging from the undersides of the leaves. As such, goldenrod is likely vital to the existence of these impressive migrations.

Seaside goldenrod provides important fuel for monarch butterflies on their journey south to Mexico each fall.

It is time to give goldenrods a place in the garden. Trust me, goldenrod will quickly become a mainstay in your fall garden, its luminous flowers revealing a whole hidden world of insects right in your backyard. You’ll wonder why you hadn’t planted it earlier, and the pollinators will thank you, which is certainly nothing to sneeze at.

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How to help the monarch butterfly

The monarch butterfly (Danaus plexippus) is one of our most iconic pollinators, known for its large size, bright orange color, and impressive fall migration to Mexico. Yet the monarch’s recent listing as endangered on the IUCN red list has led many to wonder what steps to take to help the monarch in their own yards. Read on to learn TPI’s advice to those looking to help monarchs and for a guide to noticing the different life stages of monarchs in your garden.

Monarch butterfly (*Danaus plexippus* ) nectaring on goldenrod

1. Plant milkweed

As caterpillars, monarch butterflies can only feed on milkweed (plants in the genus Asclepias), meaning these host plants are necessary for the monarch’s survival. There are several species of milkweed native to the northeast, including common milkweed (Asclepias syriaca), butterfly weed (Asclepias tuberosa), and swamp milkweed (Asclepias incarnata). Butterfly weed and swamp milkweed both perform well in gardens – the former preferring dry soils and the latter preferring wetter soils – and can be found at most garden centers. Swamp milkweed also has shallower roots, which means it can grow well in a container if garden space is limited.

2. Plant nectar-rich flowers

Unlike the caterpillar stage, adult monarchs are not limited to milkweed and feed on a wide array of plants for nectar. These sugary resources extend their lifespan and give them the energy to fly farther and make more offspring. TPI has many resources to help you make your garden even more friendly for monarchs and other pollinators, including plant lists, a guide on how to leave swamp milkweed stems for bees and this blog post!

3. Don’t take eggs or caterpillars off of plants

Although it is tempting to take in any eggs or caterpillars you see to keep them safe and watch them grow, it can actually do more harm than good. Rearing large numbers of monarchs inside can increase the incidence of disease within the population. And, even worse, recent research has shown that monarchs reared indoors without natural environmental cues are less able to migrate south in the fall. While raising monarchs can be a great educational experience, we recommend instead making a daily habit of watching the progress of the wild eggs and caterpillars you find in your garden (See below for our guide to finding monarchs in the garden!).

4. Don’t apply pesticides to your garden

Milkweed plants often become infested with tiny orange aphids (Aphis nerii). Do not worry–this is a totally natural occurrence and won’t hurt the monarchs. Aphid infestations can be unsightly but refrain from using pesticides as this will harm the monarch caterpillars. To remove aphids, use natural methods like a spray of soapy water. Natural predators such as ladybugs, lacewings, and their larva will also take care of the aphids!

Oleander aphids (*Aphis nerii*) on swamp milkweed (*Asclepias incarnata*)

How do you know if you have monarchs using your garden?

Monarchs are easy to spot as adults but we don’t see them as frequently as caterpillars. Here are some tips on identifying monarch presence in your garden:

Adults

Adult monarch butterflies are highly conspicuous––look for a big orange butterfly with black veins. They glide around with their wings held in a “V” and visit gardens to lay eggs on milkweed and drink nectar from flowers. Similar looking viceroy butterflies are smaller and hold their wings flat when they glide. Monarchs like a variety of garden flowers for nectar including purple coneflower, swamp milkweed, joe-pye weed, mexican sunflowers, and zinnias.

Adult female monarch ovipositing (egg laying) on swamp milkweed (Asclepias incarnata)

Eggs

Monarch eggs are sesame seed sized, a creamy white color, and slightly pointy–like a tiny hard boiled egg. These eggs are singly laid, meaning there is only one egg instead of a mass of many eggs. Monarchs tend to oviposit on the underside of leaves, but eggs can also be found on other parts of the plant, especially the flower heads. If you want to find eggs, patiently search the undersides of leaves and flower heads, especially focusing on the tallest areas of the milkweed, where monarchs tend to land. It may take a few days of checking before you see an egg, but don’t be discouraged! Even if you don’t see a monarch laying eggs on your plants, your garden may still have them–an adult monarch can lay an egg in under 5 seconds! Lastly, remember that although monarchs can start appearing in our region (MA) as early as the start of May, they are not widespread until late June, so time your searches for July-August if you want the best chance of success.

Closer look at a monarch egg, PC Jay Cossey

Caterpillars

Monarch caterpillars hatch in 3-5 days and eat their very first meal: their eggshell! These baby caterpillars are very small and difficult to spot. They are vulnerable at this stage to hungry insects like paper wasps. As they eat milkweed leaves, the caterpillars grow bigger and molt through stages called instars. You can tell a caterpillar’s approximate age by identifying its instar – monarch caterpillars go through five instars before pupating. Most of the caterpillars we find in the wild are small (in their first or second instars): due to the high rates of predation on these small stages, it’s less common to see large caterpillars.

First instar monarch caterpillar eating its egg

While these small caterpillars can be difficult to spot, their feeding damage can be more apparent: it takes the form of small ‘windows’ into milkweed leaves, half-chewed holes often carved into a small circle, which the caterpillar uses to avoid drowning in the milky latex exuded by its host plant. If you see frass (caterpillar poop: poppy seed-sized brown pellets) or large missing chunks from the edges of the milkweed leaves, then be on the lookout: these are the telltale signs of a much larger stage 4 or 5 caterpillar! Be sure to check under the leaves, as caterpillars of all stages prefer to eat from beneath the leaf, where they are more sheltered.

Small black frass surrounding a second install caterpillar

Pupa

Monarch pupa are hard to spot as they blend into the surrounding environment. The 5^th instar caterpillars tend to crawl away from the milkweed to pupate on nearby plants. They will remain in the pupa for 7-10 days before emerging as a beautiful monarch butterfly.

Have you found monarchs in your garden? Share your photos to @pollinatetufts!

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Summer recap: a glimpse at pollinator fieldwork

The growing season is a busy time for pollinator scientists. Here’s what members of TPI got up to this summer!

Cellophane bees

Nick, Leslie, and Lydia dug into the secret lives of solitary bees in New Hampshire. They want to know “where does a bee fly in her life?” To answer this, they caught and painted blueberry cellophane bees at nests to identify unique individuals. Then, they surveyed flowers and nesting areas to track daily movements. They painted over 1200 bees!

Bumble bees

Jessie, Lauren and Liana planted hundreds of goldenrod and sunflowers to find out how our growing practices affect the food available to bumble bees — an important native bee that pollinates tomatoes, peppers, melons and more. Bumble bees (like other bees) eat pollen and nectar, and need abundant, high-quality food to fly, pollinate, and raise new bees. They want to know how fertilizer and drought change plant growth, the number of flowers they produce, and the nutrient breakdown of their pollen and nectar. They spent the early summer digging, planting, weeding, and watering and ran a choice experiment to find out which plants bumble bees prefer to visit.

Baltimore checkerspots

Brendan spent the spring and summer studying the impact of the Junonia coenia Densovirus on Baltimore checkerspot population dynamics. He set up an enclosed experiment that exposes caterpillars to a gradient of viral loads and monitored the impact on their survival and reproduction. Later in the summer he continued field sampling for a project that is using a metagenomic approach to investigate whether Lepidopteran viruses are shared between co-occurring caterpillar species. This will help him understand the likelihood of disease spillover impacting species of conservation interest.

Honey bees

Isaac and Greta studied the effect that temperature stress has on the way honey bees arrange their comb stores. They hope to learn how increasing global temperatures will affect the structure of honey bee colonies.

Milkweed visitors

Atticus, Karen, and Kristina are looking at pollinator usage of milkweed in urban environments. Atticus and Karen observed monarch egg-laying behavior on milkweed, the monarch butterfly’s host plant, to see if it changes depending on surrounding landscape contexts, such as differing neighborhood flower garden densities. Kristina looked at milkweed flower visitors to see how visitation rates and species richness are affected by flower garden densities. You may have seen their pots at various park locations in Medford and Somerville!

Sweat bees

Chloé, Nick, and Aviel studied sweat bee (Agapostemon virescens) movement on Tufts’ campus. They want to know whether roads act as barriers to foraging bees. To answer this, they set up squares of four pots of coneflower bisected by roads at three sites on campus. At these sites, they caught and painted bees to identify unique individuals and recorded ongoing traffic.

Yellow-faced bumble bees

Across the country in California, Sylvie is studying the difference in life cycle patterns of Bombus vosnesenskii, the yellow faced bumble bee. Sylvie is interested in how life cycle timing of this bumble bee varies across its range. In the Sierras, B. vosnesenskii displays the characteristic timing of bumble bees – a queen emerges in spring, a colony grows over the summer with female workers, and at the end of the summer the queen stops producing workers and starts producing new queens and males. Then, the mated female queens overwinter underground! Sylvie is getting to discover firsthand the timing of Bombus vosnesenskii life cycle on the coast–and how it compares to timing in the mountains–since it has not yet been characterized!

Pipevine swallowtails

James and Kaitlyn mated adult pipevine swallowtails and tested how growth rates in their offspring may be affected by differences in ambient temperature. These females laid eggs on Dutchman’s pipe and they collected those eggs to put in different thermal treatments. They will monitor those larvae until they’re ready to become adults themselves.

Monarch butterflies

Also in California, Emily studied monarch butterflies in urban gardens in the San Francisco Bay Area. Most people know monarchs for their impressive yearly migrations. Recently, however, year-round breeding ‘resident’ monarchs have also established in coastal cities in Northern California. These residents are associated with non-native milkweeds – namely Tropical Milkweed (Asclepias curassavica), which do not die off in the winter as the native species do and therefore provide breeding habitat throughout the year. We don’t yet know yet how resident and migratory monarchs interact with one another in urban gardens, and what the consequences of these interactions may be. In her research, Emily hopes to understand whether the resident monarchs in urban gardens are a population that is independent of the migratory one, or whether the presence of residents and their non-native host plants are contributing to overall monarch declines in the West.