Time to cut back the Asters

Driveway garden before cutting back...

If you are growing tall native asters or goldenrods, mid-June is a good time to cut them back by a third to a half.  This will give more blooms on a slightly shorter plant.  It also reduces the tendency of these plants to flopping over.  I did this yesterday in this driveway garden.  Prairie Aster (Symphyotrichum turbinellum) dominates the right side of this planting.  Cutting back not only reduces flopping, it also makes it easier to see some of the other plants, like purple coneflower and common milkweed.  

After cutting back its easier to see the shorter flowers

I have cut back asters as late as the end of June.  Goldenrods can get the same treatment, but I found that I severely reduced the number of flowers on the early blooming Stiff Goldenrod (Solidago rigida) by cutting back too late in the season.  The later blooming Seaside Goldenrod (S. sempervirens) did just fine.

Two stalks of Canada Toadflax

As I was cutting back these fall bloomers I noticed several clumps of the native Canada Toadflax (Nuttalanthus canadensis, formerly Linaria canadensis) in bloom.  I have been seeing these along the highway since the beginning of June, but this is the first time I have been moving slow enough to get a good look.  They usually show up in large masses and can look like a pale blue cloud while driving by.

This winter annual or biennial wildflower grows in full sun and rocky soils where they have little competition from other plants.  The one in this photo was growing right on the edge of the asphalt, despite having much better soil nearby.

Close-up of Toadflax flower

Winter Weeds, Part 1

On nice winter days it is fun and interesting to take a walk through some of the wilder areas to see what plants are still standing.  An excellent guide book for this is Weeds in Winter by Lauren Brown.   This book has all kinds of useful information for winter plant ID in New England.  There’s a glossary of terms, a dichotomous key for plants described in the book and some really great illustrations of the winter appearance of these plants.  

Since this winter has been so mild in southern New England, I was able to find many of these plants right around my house.  These normally would have been crushed under piles of snow.  In fact, I found so many of them I need to split this post into two parts.  Most of these photos were taken at the end of January this year.  Here is the first of two installments of photos of my winter weeds.  

This Prairie Aster retains its strong
stems through the winter

These photos are roughly in alphabetical order.  I had already decided on the order when I remembered the name changes for the asters, so Symphyotrichum is coming first.

Aster can be difficult to ID in the winter.
Fortunately, I remembered which is which in this case.

Many of these native asters have long lasting stems.  For example, the 'bush' on the far right in the topmost photo is a Prairie Aster.

The Bigleaf Aster still has some of its seeds.

When I came across this old stem of the American Bellflower I was not sure what I was looking at.  After I few minutes I remember what had been growing in that location and narrowed it down to this species.  One advantage of using the plants around the house is that ID is a lot easier than when working in the field.

American Bellflower has distinctive seed capsules.

Sweet Pepper Bush looks like a tangle of branches in winter.  Closer examination of the older branches shows that it has exfoliating bark.  It is more easily identified by its flower spikes that stay on through the winter.

The long styles of the pistil are retained
on these dried Sweet Pepper Bush flowers.

I usually don't see the Pink Tickseed in winter.  It's growing out of the driveway and is usually covered with snow.  On close examination you can see the narrow little leaves have already started coming up.

Pink Tickseed is only 6-8" tall.

The new buds on this Sweetfern are beginning to swell.
The hairs on the stem really show up in the afternoon light.

The low angle of the sun really enhances the appearance of the stems and spent flowers of these plants.  This is particularly true for the taller plants like these River Oats.

The seeds of the River Oats are shed
slowly over the coarse of the winter.

Purple Coneflower is one of the easier plants to identify.  The old flowers retain their cone-shape even thought the seeds are long gone, either eaten by birds or scattered in the wind.

Seeds of the Purple Coneflower are all gone now

Even though it's dried up American Pennyroyal
still has its minty scent.

The last plant in this post is the American Pennyroyal.  This low growing annual is usually buried under snow there is nothing left of it when the snow melts.  The dried calyxes are arranged in whorls around the stem.  These are much easier to see now that all the leaves are gone.

Well pregame is nearly over, so it's time to close down the computer and start watching the Super Bowl.

Go Pats!!!!

Asters in New England

Another thing besides beautiful foliage that New England has in the fall is an abundance of native asters. In the Massachusetts County Checklist there are 27 species of Aster indigenous to Massachusetts. (Technically speaking, however, there are no more New World asters, they have been reclassified into a number of new genera including Doellingeria, Eurybia, Ionactis, and Symphyotrichum.)  A few of these native species, such as the purple New England Aster (Symphyotrichum novae-angliae) and Bushy Aster (S. dumosum) have become common in many gardens with cultivars such as ‘Alma Potschke’ and ‘Wood’s Purple’.  I would like to call attention to some commercially less common species that I have purposely grown or that have appeared around my house.

One of my favorites, which I have grown from seed is the Smooth Aster, Symphyotrichum laeve. This is a medium tall aster that grows in full to part sun and relatively dry soils. Its stems are strong enough that it does not always needed to be staked. However like many asters cutting back by 1/3 at the end of June gives a stronger, bushier plant. The flowers are usually a lavender blue measuring over 1” wide. In this photo are some freely seeded plants that show some variation in flower color. These are most commonly commercially available as the ‘Bluebird’ cultivar.

The Big-leaf Aster, Eurybia macrophylla, is early blooming and grows well in dry shade. My plants started blooming in late June and did not start going to seed until early September. Here we see the fuzzy seed heads and a few residual blooms. This species will spread by both seed and rhizomes. It forms dense mounds of foliage and can be used as a ground cover.  And It's still not bad looking when the seed heads replace the flowers.

Another shade tolerant species is the White Wood Aster, Eurybia divaricata. This species also grows in dry shade, e.g. upland woods. It blooming period is later than for the big leaf aster and it can be a vigorous spreader. This photo was taken at Mount Auburn Cemetery, but they are quite common in the woods in New England.

Two species that grow like weeds around my house are Heart-leaved Aster and Arrow-leaved Aster, Symphyotrichum cordifolium and S. urophyllum, respectively. Structurally these two asters are very similar. The most obvious difference is that the flowers of Heart-leaf asters tend toward blue-violet shades, while the Arrow-leaved asters are whiter.

In the garden they form clouds of light colored flowers that stand out against darker colored foliage.

I purchased the Heart-leaved aster thinking it would combine well with my yellow cone flowers (Rudbeckia), but the cone flowers are just passing as the aster begins to open up in mid-September. I need to find a later blooming yellow for this combination to work, such as the annual Black-eyed Susan (Rudbeckia hirta), or a late blooming Goldenrod like the ‘Fireworks’ cultivar (Solidage rugosa ‘Fireworks’). The Arrow-leaved aster just blew onto my property on its own.

 

The last aster that I have been working with is the Smooth Violet Prairie Aster (S. turbinellum). This aster is not native to New England, rather its home is in the Plains States. I got this plant for use in a parking lot island, where it gets no extra watering or special care, 4 years ago and it is still going strong. It has profuse blue-violet blooms from September to October on relatively stiff stems. The only care I give this plant is to cut it back by 1/3-1/2 in late June to keep it from getting too tall and flopping over.

 

My first preference was to use the Smooth Aster (a New England Native) on this site, but that plant was not available at the time of installation. I had only a single pot of Smooth Aster to put in at the time.  While it is still surviving there, the Prairie Aster is really doing well in that location (and the bees love it, too).