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Aster - Care Guide
Growing Aster – Michaelmas Daisies
The asters which we grow are clump forming rhizomatous perennials with slender branched stems and stalk less lance shaped leaves. The flowers brighten up most herbaceous borders from late summer and on into autumn. The last great show of the season before the onset of autumn.
Asters grow well and will form expanding clumps in well cultivated, fertile, moist soil in full sun. They naturalise well in uncut grassy areas and often spread from gardens along railway lines and into native hedgerows. Near Truro Aster novi-belgii ‘Royal Velvet’ has colonised a whole waterside meadow and produces a tremendous show in September and October.
Taller growing asters will definitely need plant supports to keep the flowering shoots upright in wind or heavy rain. It is best to position these supports in place in late spring and allow the plants to grow up through them on their own. This is also true in the nursery where a cane support will be needed for best results with the taller growing varieties.
Once flowering is over all your asters should be cut back hard to ground level. This will encourage the clumps to spread and develop and it is good practice to mulch over these plants in the autumn to protect them from frost and improve the ongoing fertility of the soil.
When preparing a border to grow asters it is worth taking the time to dig well-rotted manure or leaf mould into the ground before you start planting. Asters will happily grow away and spread undisturbed for many years so it is important to get a good start.
Asters are very easily propagated by division in the spring or autumn. Simply lift a clump with a spade or fork and gently cut off as many vigorous outer shoots as you need. Once your clumps start to develop hollow centres it is probably time to dig the whole clump up and start again with fresh offsets from the same plants. Perhaps every three to five years for best results.
In hot dry periods your asters may get stressed and develop powdery mildew; in very wet summer weather grey mould or botrytis may be a problem on occasion. If caught in time you can prune your plants back in the hope that they will regrow and develop flower stalks later in the year. However, in the main, these plants are hardy and vigorous enough to shrug off these short-lived problems.
Images to follow.