September is a wonderful month with its misty morning and warm days. It is also a time when the garden is beginning to fade away, so brightly coloured autumn flowers as important for bringing that touch of gaiety back into the garden.
Most Asters are easy to grow. They originate from the USA. They all have daisy-shaped flowers that range in colour from white to blue. There are no yellow asters, but the yellow centres add a touch of yellow. In shape they can be upright, broad and spreading or short and dome shaped.
The most easily recognised asters are the upright Michaelmas daisies, also known by the Latin name of Aster novi-belgii (or the New England aster). The flowers are usually about the size of a £2 coin, and either double or semi-double in shape. In colour they range from white to purplish-red, with lots of blues, pinks and purples in between. In height they can be as short as 15 cm (or smaller) right up to about 120 cm. They all have shiny dark green leaves, and here lies their downfall. They are susceptible to mildew, which is most prevalent during warm, damp periods. Don't let this put you off. One way of reducing the risk is to make sure that there is lots of room around the them. This allows air to move around the plant and so disperse fungal spores that cause mildew. If I were to choose just one variety it would be Aster novi-belgii 'Marie Ballard' with its pretty, powder puff like, lavender flowers.
For those gardeners who would like the effect that the Michaelmas daisy gives you, but don't want the worry of mildewy leaves, the New England asters, Aster novae-angliae are a better choice. Not so varied in either colour or shape they produce the same shaped flowers, but on more rigidly upright stems. Thes are clothed with soft green, hairy leaves, which do not suffer from mildew. Again they can either be short or tall, but in colour the flowers are only white, pink and purple flowers. Personally I really like Aster na (short for novae-angliae) 'Purple Dome' for it's vibrant purple flowers which really stand out on misty days.
Some of the most lovely asters are not so well known to gardeners. These are more softly coloured, producing in white, soft pink or lilac. Many of them grow into broad plants, have small leaves and the daisy shaped flowers with slim petals. The ones I have grown grow from around 75 cm to 90 in height and have blooms that can be as small as a 5p piece or as large as a £2 coin. All of them produce so many flowers that they smother the clump of leaves. One of the best of these is Aster x frikartii 'Monch'. This begins to bloom in late August and by the time September arrives it has formed a broad mound of soft green leaves which is covered with large, soft lilac flowers.
At this time of year plants that provide food for bees and butterflies are very important. Asters with their centres of small florets (the disc in the middle) allow insects to easily feed on pollen. With just a few in the garden, not only will you have colour from August until the first frosts, you will be helping bees, butterflies and many other fly insects prepare for the winter.
by Claire Austin
Posted on 08/09/2010