Wednesday, September 16, 2009

Asters' Glory

When summer flowers begin to fade, asters steal the show. From late summer to fall, these delightful perennials adorn the garden with blankets of color.  Aster (pronounced ASS-ter, meaning "star" referring to the shape of the flower) is a group of over 600 species of flowering plants native to Europe, parts of Asia and North America.  Their late bloom time has earned for some of them the common name "Michaelmas Daisy" for the Christian Feast of St. Michael and All Angels which falls on 29 September.

It would have been far too simple to leave all of the species in one big genus, Aster.  So in the 1990s, after intense observation, almost all of the North American species were spun off into new genera.  Those include Almutaster, Canadanthus, Doellingeria, Eucephalus, Eurybia, Ionactis, Oligoneuron, Oreostemma, Sericocarpus and Symphyotrichum.  Not impressed, most gardeners and aster growers have resisted the new names, preferring to stick with the older one.

You know that summer is waning when asters bloom.  Shades of pink, blue, purple and yellow, and white color the landscape.   As the days shorten, they seem to me at once extravagant and melancholy.

Rose Kingsley observed in The Autumn Garden,

"In the garden, Autumn is, indeed the crowning glory of the year, bringing us the fruition of months of thought and care and toil.  And at no season, safe perhaps in Daffodil time, do we get such superb colour effects as from August to November."

Asters generally thrive in full sun in USDA climate zones 3 through 8 in well-drained soils with pH ranging from 5.1 to 6.5.  The flowers attract butterflies, and bees, but the plants are unattractive to deer.  They are generally heat- and drought-tolerant, therefore are well-suited to exposed perennial gardens, wild-flower gardens, butterfly gardens and xeriscaping.  Because it of its medicinal properties, herb gardeners sometimes include Aster tartaricus in their collections.  Gardeners interested in native species have many to choose from.

Prepare the planting bed by cultivating at least 8" deep, removing all traces of weeds. Compacted soil should be cultivated to 12" deep.  Add enough soil to raise the bed at least 4" above the surrounding ground level. This will help to promote good drainage. Composted manure may be incorporated into the soil.  Incorporate 5-10-15 fertilizer at a rate of no more 2 lbs. per 100 square feet into the top 4" to 6" of soil. Avoid synthetic fertilizers contacting any part of your plants.

Space asters 12" to 18" apart. Dig planting holes into the cultivated soil a little less deep than the depth of the growing container. Place the plants into the holes and back-fill, watering as you go. Press soil around the root balls. Do not cover entirely the root balls with soil. The tops should be slightly exposed. Add a top-dressing of mulch around the plants, not on top of them, about 1" deep.

Because it likes well-drained soil, plant asters with other plants having similar cultural requirements.  Fertilize sparingly and allow soil to dry between watering.  Occasional pruning helps to maintain compact plants and produces more blooms.

Asters have their afflictions including fungi, nematodes and various insects.  But good gardening practices such as providing good air circulation, removal of dead and diseased material can help to prevent them .

Many of us plan our gardens around spring and summer.  There is nothing wrong with that.  But it would be a shame to neglect shades of autumn.  Asters, by whatever name, add richness to the landscape.  Be sure to include some in your late garden for the crowning glory of the year.

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