I’ve had a problem with many of my sedum (or is it sedums?) this year in which they fall over. In the picture to the right you’ll notice the stems all lying flat on the ground.
I’ve researched this issue and found it to be farely common with a variety of possible culprits. This is also not a problem limited to stonecrop, but many many many types of flowers.
If this problem is happening to you, here are the possible reasons why:
1. The cultivar you are growing may have been bred for bloom size at the expense of stem strength. Once those big flowers form, it droops. Of course some plants, like peonies, almost always droop anyways, but if you know other cultivars of this type of plant do not droop, then it could be breeding.
2. Your soil is too rich. Believe it or not having soil that is too rich can cause flowers to droop. The reason is that they grow taller and with larger flowers than normal and their stem just doesn’t get the strength to catch up. This can also happen if you get too much water, really anything that spurs above average growth.
3. Another problem caused by over watering is rot or various diseases. The base of stems are close to the ground, where it is often wet. If the stems rot then nothing will be supporting the flowers and they’ll fall over. Various fungal or bacterial problems can afflict stems as well. Be sure to examine your plants for signs of disease.
4. Abnormal wind and rain or snow can cause stem weakness. For many plants once the stem is bent it will never regain it’s upright stature.
5. The plant is planted too shallow, the roots do not provide adequate anchoring.
For me I believe my problem is caused by #2. I know these cultivars do not normally droop. I also know that Sedum are adapted for harsh conditions with poor soil and little water and while I do not provide them with any extra water during the growing season all my garden beds were made with very rich soil. I the future I will be sure to avoid fertilizing those portions of the garden and possibly provide supports.