Friday, November 19, 2010

Berries and Bark at Tower Hill

I just attended the annual 'Trees in the Urban Landscape Symposium' at Tower Hill Botanic Garden in Boylsten, MA, yesterday.  It was a beautiful (but windy) day at a beautiful location.  I'll talk about the symposium in a later post, but for now I'd like to show you the site.  If you haven't been there recently, or at all, they have just opened a new Winter Garden and Limonia, which are great places to visit as the weather turns cold.

View of the Farmhouse across the Lawn Garden at Tower Hill
The last part of the symposium was a walking tour of these new areas and their Lawn Garden by Joann Vieira, Horticulture Director, Tower Hill Botanic Garden and Executive Director, John W. Trexler.  Most of the leaves are gone from the trees and deciduous shrubs to reveal some of the highlights of the plantings.

Beautyberry with Paper Birch and Winterberry Holly
This scene was really lit up by the afternoon sun, with the native Paper Birch and Winterberry Holly, Ilex verticillata, in the background and Purple Beautyberry, Callicarpa dichotomata, up front.  The bright red berries of the Ilex are very popular with the birds, especially later in the season, while the non-native beautyberry is less favored, providing more visual interest than wildlife value. 

Another striking planting with a lot of winter interest was this cluster of 3 Paperbark Maples, Acer griseum, surrounding a mass of 'Brower's Beauty' Pieris.  Some other interesting plants in this garden include some of the most luxurious Japanese Plum Yew, Cephalotaxus harringtonia 'Prostrata', and Siberian cypress, Microbiota decussata, that I have ever seen. Alas, no photos of these.  These two plants do show some resistance to deer browsing, a problem in this area.  There was also a large Boxwood, Buxus sempervirens ‘Newport Blue’, at 5-6’ tall and wide that seems to be doing quite well at this zone 5 location. There was also a native Inkberry, Ilex glauca f. leucocarpa, that had white berries and a form more like the species than a compact cultivar.  These berries do show up much better than the black berries that are normal to this species.

Winter Garden at Tower HIll
The new Winter Garden was designed to hold as much interest when viewed from the inside of the building as it is close up outside.  This row of Bloodtwig Dogwoods, Cornus sanguinea 'Midwinter Fire', really shows well as the leaves are lost and will not interfere with longer views across the garden, even as they grow taller.  This garden features a lot of low growing and other 'specialty' conifers. 

Leucothoe fontanesiana 'Scarletta'
One of the native plants used here is a low growing cultivar of Fetterbush, Leucothoe fontanesiana 'Scarletta'.  When protected from winter winds this plant is expected to grow 18-24" tall and have the scarlet tinged foliage in spring and fall.  I find this a much more appealing plant than the 'Girard's Rainbow' cultivar, that is common in the trade. 

So far my visits to Tower Hill have been limited to the Urban Tree Symposia in the fall, but I will need to make the 45 min drive from Boston in spring or summer so that I can appreciate more of what this garden has to offer.  Tower Hill Botanic Garden is currently open Mon-Tue,Thu-Sun 10am-5pm and Wed 10am-8pm.

Monday, November 8, 2010

Making good use of all those leaves

Well we've had a pretty nice fall foliage season in New England this year, despite all the dire predictions that our unusually hot and dry summer would play havoc with foliage season.  The inevitable end to foliage season is leaves on the ground that need to be cleared away.  I've always hated the idea of buying bags to stuff with leaves in order to throw them away.  That's kind of like throwing away money, isn't it. 

A few years ago the maintenance staff at Mount Auburn Cemetery began a practice of mowing leaves directly into the lawns rather than picking them all up and transporting them to a compost yard.  When you consider that leaves contain most of the minerals that the roots have taken out of the soil, returning those minerals to the ground essentially supplies the trees with the raw materials they need to produce a new crop the following year. 

Pros for mowing in leaves:
  • No raking
  • No leaf bags
  • Relatively fast
  • No transporting leaves for disposal
  • Free fertilizer, may skip lawn and tree fertilization
  • Naturally builds soil organic content 
  • No special equipment (just a mulching mower)

  • Some leaf dust and scraps remaining
  • Need to make an extra pass with lawn mower
  • Dry leaves are abrasive toward lawn mower blades
  • Some leaves, like walnut, contain compounds that retard growth of other plants

Since I've learned about that practice, I've been using it at home for the past two seasons.  This year my goal is that I will dispose of no leaves off of my property.  The following images show before and after shots of mowing the leaves into the lawn.  This job took me about 15 min, while raking and bagging would have taken at least an hour.  If the grass was a little taller or I hadn't waited so long between mowings, most of the debris would have disappeared immediately.  Also, since I have been doing this I have reduced the fertilization of the lawn to a single treatment with slow release fertilizer in the spring.  (I'm not a turf expert, but this works for me.)


For the leaves in the shrub beds, I'll rake and/or blow them out then run the leaves through a chipper which reduces the volume about 5 fold.  These leaves I'll save for a month or two then use them as a mulch on the garden and perennial beds. 

Some more ideas about how to treat fallen leaves and their benefits can be found at this link to Ecosystem Gardening

Monday, November 1, 2010

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).