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Goldenrod – Native plant of the week

Goldenrods, or members of the genus Solidago, are a truly essential part of our native landscapes, and suffer from some common misconceptions. This week, we’ll look at why goldenrod is so important, clear up those myths, and check out some common species you can cultivate – to help native pollinators, and for your own enjoyment! 

First of all, about that pesky myth: that goldenrod pollen causes allergies.  

In fact, the plant primarily responsible for those seasonal allergies, sometimes called hay fever,  is ragweed. Ragweed is pollinated by wind rather than insects, so it has tiny inconspicuous flowers that produce copious amounts of extremely fine pollen, which then drifts through the air in hopes of landing on other ragweed flowers – irritating the respiratory systems of unfortunate humans along the way. Goldenrod, on the other hand, is pollinated by insects, so it produces heavy, sticky pollen to attract and nourish them. The insects pick up some of the pollen when they visit to eat it or drink the flower’s nectar, and then transport it to the next flower they stop at – hopefully another goldenrod plant. This pollen never becomes airborne (unless perhaps you bump into or shake the plant, in which case some might fall to the ground), and therefore does not cause allergies. 

Ragweed on the left, compared to goldenrod on the right
Ragweed is on the left, and goldenrod is on the right.

How did this get mixed up? While the two plants look very little alike, it probably stems from the fact that they bloom around the same time. Since people don’t notice the flowers of ragweed, they probably see the shaggy, bright yellow (pollen-colored) blooms of goldenrod, and assume that it must be the source of their suffering – then spread this mistaken assumption around. This unfortunately discourages some people from cultivating goldenrod.  

Goldenrod is an extremely valuable plant to pollinators and other insects. It is a keystone species in many North American ecosystems – meaning so many other species depend on it that if it was removed the entire system would change drastically. In goldenrod’s case, this is mostly because so many things like to eat it: around 130 species of lepidopterans (butterflies and moths) use it to host their larvae, just in our area! Plants in the Solidago genus are the only host for many of those species. These butterflies and moths are not only pretty, and important pollinators themselves, but both larvae and adults are also crucial food sources for many species of birds, especially for parents trying to feed their young. 

A few of the species that solely rely on goldenrod are the Asteroid Moth or Goldenrod Hooded Owlet (Cucullia asteroides), the Diamond Spot Pearl or Beet Webworm (Loxostege sticticalis), the Bilobed Dichomeris Moth (Dichomeris bilobella), and the Confused Eusarca (Eusarca confusaria).

Three beige moths
Top left: Eusarca confusaria (photograph by Andy Reago & Chrissy McClarren, distributed under a CC BY 2.0 license). Bottom left: Loxostege sticticalis (photograph by Marcello Consolo, distributed under a CC BY-NC-SA 2.0 license). Right: Cucullia asteroides (photograph by Andy Reago & Chrissy McClarren, distributed under a CC BY 2.0 license).

Aside from hosting the larvae of so many insects, one of the most important roles goldenrod plays is providing abundant nectar and pollen to feed pollinators in the late summer and fall. When many other flowers are slowing down and ending their blooming season, goldenrod fills in as a primary food source for these insects and other animals. This is especially crucial to migratory butterflies like Monarchs, which rely on this plentiful, easy-to-find nectar during their flight south in the fall.  Read more Goldenrod – Native plant of the week

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Phlox – Native Plant of the Week

Many people have strong feelings about phlox. Some love its beautiful blossoms and others are frustrated by the deer browsing and its spreading nature. Regardless of which side you lean towards, there are good reasons why it’s a popular garden plant, and since some species are native to the North Country, let’s take a closer look at a few of those! 

First though, a bit about the genus: Phlox is a group of perennial flowering plants, most of which are native to North America. They are frequently cultivated by humans for their showy and often fragrant flowers, and with many different species to choose from and countless varieties and cultivars, it can be extremely versatile in a garden. In fact, the genus name Phlox comes from a Greek word meaning flame, in reference to the vibrant flowers of some varieties. Phlox flowers are a tubular shape which divides into five petals – although you may occasionally find a four- or six-petaled blossom in a cluster. The flowers often have a color difference in the center around the opening, which serves as a guide for pollinators seeking nectar. 

Two examples of phlox flowers with concentrated pigments toward the flower centers.
Note the concentrated pigments at the centers of the flowers.

Let’s start with a true-blue wild native – Phlox divaricata, which goes by common names including timber or wood phlox, wild sweet william (not to be confused with Dianthus barbatus, which is also called sweet william), and wild blue phlox. Its native range covers the central and eastern United States and eastern Canada, growing wild in forest floor environments, where it may grow in clumps or spread more horizontally, reaching 6 to 12 inches high. In gardens it prefers partial to full shade, and moist well-drained soil that is high in organic material, to approximate its natural growing conditions. P. divaricata blooms in the spring, starting as early as April. The wild type is typically a light blueish purple color and has narrower, more separated petals than most phloxes, but cultivated varieties and cultivars can range from bright violet pink to blue and sometimes white, and flower shape may be similar to other domestic species. 

blue cheerful flowers growing wild by a rock
Phlox divaricata, or wild blue phlox.

Next, Phlox subulata, which is known commonly as moss phlox, creeping phlox, thrift, and more rarely, moss or ground pink. Interestingly, “pink” is a name which this phlox shares with some members of the Dianthus genus, from which we get the word for the color pink. P. subulata is also native to central and eastern Canada and the U.S., and is most prevalent in the Appalachian Mountains. It has a very different growth habit than some of the other species, with trailing stems spreading from a single base to form a dense mat of foliage – about six inches high and two to three feet wide. Stems become woody with age, and foliage becomes sparser in the center of the plant as new growth continues around its outer edges. If you want to maintain density at the center, the stems can be cut back to about half their length when the plant is done flowering. P. subulata can be grown in sandy or gravelly soil, as it often does in the wild, and it is more tolerant of hot or dry conditions than most other species of phlox. It grows in a variety of colors, is spring flowering like P. divaricata, and has a bit smaller flowers than the other two species (about ¾ inch wide).

Low, dense pink flowers and vegetation
Phlox subulata, or moss phlox.

The last species we’ll look at is garden phlox – Phlox paniculata. Some other common names for it include autumn or fall phlox, summer phlox, and tall phlox, and you can likely guess a few of its features from that list of names. It does indeed bloom from midsummer into fall, and grows taller than most other species, about two to four feet. Here in the pollinator garden at the Extension Learning Farm, our P. paniculata has just started blooming, and past years’ records show it will be mostly done by mid-August, but may trickle into late September.  Read more Phlox – Native Plant of the Week

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Heat and Garden Vegetables

Near record breaking heat will have an impact on our garden’s vegetables.  In general, daytime temperatures that exceed 92°F and nighttime temperatures above 72F will cause problems.  The longer the heat lasts, the bigger the impact. Problems include:

Sunscald – Usually a problem with late season heat waves when loss of foliage is more prevalent, but any fruit exposed to direct sunlight can experience bleaching and browning of the exposed parts.

White spot on a green tomato
This tomato shows classic sunscald. Photo credit: Flickr

Pollination issues in cucurbits – Heat favors male flower production over female flowers, resulting in fewer fruits, at least temporarily.  It may also lead to drop of already set fruit.  Bee flights/activity is reduced in hot weather which causes poor pollination and flower drop.  In some cases, fruit will be distorted and crooked due to incomplete pollination. Cucumbers are especially sensitive to this disorder.

Tomato/Pepper flower drop – Flowers on these plants have a 48-hour window to pollinate.  High temperatures can cause pollen sterility and flower drop.  You may not notice the impact until 5 to 6 weeks later when yields are suddenly reduced for a period that aligns with the length of the heat wave.

Sweet corn yields – Although a heat loving crop, daytime temps over 95F can result in poor tip fill, missing kernels, smaller ears, and reduced yield.

Snap bean flower drop – Beans respond by dropping flowers.  As soon as temperatures cool down, flowers will develop normally.  Unfortunately, this may result in a split set, where some flowers set before the heat and others after. This is a big problem for one-time mechanical harvest but doesn’t have much impact on garden grown beans. Read more Heat and Garden Vegetables