As the result of the wind and rain, some of my Autumn Joy Sedums have their panicles parted from the others as the result of being top heavy. This creates an unattractive display. The same happens to my mums when I do not trim them back through the late spring and early summer.
If, I was to use the same technique with the Sedums, would a dense and compact display result as with the mums, or would the flower heads be eliminated?
Additionally, if it works for the sedums, would the same technique work for peonies and other top heavy plants?
There are many plants that suffer from flopping over after wind or rain. Peonies are usually the plant that makes gardeners pull their hair out when this happens – usually just before going out and cutting a few blooms for displaying indoors.
You are correct that pruning mums until about mid July does indeed prevent the floppiness that can occur after wind or rain. It also allows mums to bloom later in the summer and early fall, when we all need some colour.
Autumn Joy sedum (Sedum ‘Herbstfreude’) is a tall growing succulent, unlike most of the sedum or stonecrop as they are often named that one would find in rock gardens, which spread nicely between rocks. Autumn Joy sedum generally prefers full sun and moist, moderately fertile soil. Autumn Joy sedums that are grown in part shade or very rich soils, will often produce spindly stems, and therefore flop over. I have two Autumn Joy sedum growing on the north side of my house, and under trees. They do indeed flower, usually about 10 days after the ones in the sun. They do grow floppy stems. As a somewhat lazy gardener, I use peony rings to hold them up. They are not noticeable once the sedum grow through and above them.
However, they can be pinched, much like the mums. When the stems reach about 15 to 20 cm, the terminal buds, or top buds can be pinched back. Remove the pinched portions out of the garden. Be aware that they will flower later, much like the mums.
For more information: https://www.finegardening.com/stonecrop-sedum-%E2%80%98autumn-joy%E2%80%99
This technique is not recommended for peonies. Peonies are long-lived perennials in Canada, and are year round shrubs in the southern states. They bloom for a couple of weeks in early June, and many are scented. They grow from a fleshy tuber planted just below the soil – this arrangement is part of the reason why peonies hate to be moved. Their weakness is certainly the stems. The heavy blooms can splay down to the ground under spring rains, and scatter petals in the border. The plant needs support, usually with a peony ring. This is usually a three legged metal ring that surrounds the plant. The ring is often plastic or powder coated in green, so that it remains unnoticeable. These can be found in various sizes from almost any garden supply centre.