Hardy Aster Plants

April is the month to add color to your fall garden. Perennial asters set out now will provide month long beauty in late summer when a splash of color is most welcome in the perennial border.

There are several hundred species of hardy asters, sometimes called starwort and michaelmas daisy. They range in height from a few inches to 6 feet. Hardy asters are native to many parts of the world – North America, Europe, Asia and South Africa – and all types of habitats – swamps, dry plains, open woodlands and mountains. In spite of these varied conditions, however, the majority adapt themselves quite nicely to garden conditions. Hundreds have been developed and named (many of them hybrids).

Hardy asters are by no means new; Aster amellus has been grown in gardens for 2,000 years. It is mentioned by Vergil in “Georgics” and also by Dioscorides in his “Materia Medica.” The New York aster, Aster novibelgi, has been popular in England for over 200 years. Most hardy asters are listed under this species even though many are really hybrids.

smooth blue aster

The peak of bloom for hardy aster flowers come in August and September, just before the chrysanthemums wind up the season. While the individual aster blooms are not large, the plants are practically covered with them for more than a month.

Hardy aster plants are not demanding in their needs; they prefer good garden soil in a spot where they will receive full sun. The Aster novibelgi types need a little more moisture in the soil than the others but all, with few exceptions, are perfectly hardy and increase rapidly under average conditions. The best time to plant or divide them is early spring. When lifted gently and pulled apart, each shoot will make a new plant. For best results, they should be divided every two years or only three strong shoots should be allowed to develop on each plant.

About the only necessary fall chore is to cut the tops off a few inches above the ground after the plant has finished blooming. This prevents seed from forming and the resulting chance seedlings around the base of the plant.

The tall varieties, which normally grow 4 to 6 feet high, can easily be kept down to a height of 2-1/2 to 3 feet by pinching as is done with chrysanthemums. Pinch out the tip of the main shoot when it is 6 inches tall and the tips of the side branches when they are 8 to 12 inches long. Additional pinches can be made to shape the bush but all pinching should be stopped by the middle of July. If you plan to let the plants grow to their full height be sure to have in front smaller plants at least 2 feet high. These will hide the base of the asters whose leaves often fall off.

Most of the tall hardy asters are of the novaeangliae type. This is my favorite type of aster, when pinched to form a low solid spot of color the size of a bushel basket, and its woody stem makes it practically indestructible. Among these tall varieties are the finer, clearer pinks.

The novibelgi type aster plants are of medium height. These do not require pinching as the plants are well branched close to the ground. Some will need slight support. A few twiggy branches underneath will keep the plant off the ground.

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