Answer: Four o'clocks are Mirabilis jalapa. These plants are perennial in warmer areas but are usually grown from seed each year in your area.
There are two types of hibiscus shrub. Hardy hibiscus shrubs are called Hibiscus syriacus. The hibiscus we typically see used as a potted patio plant is a tropical plant and not hardy in cold winter areas. It will not tolerate frost. There are also perennial hibiscus plants with very large flowers that die back during the winter and resprout late in the spring, sometimes not until June. If this is what you planted, be patient a few more weeks.
Most sedum spectabilis types should be divided every few years when they begin to sprawl open. (Over fertilizing and too much shade can cause this in addition to old age.) To divide them (best done in very early spring but can be done in late spring or fall as well) simply dig up the plant with its roots and cut it into sections by slicing vertically with a sharp spade or knife.
Each section should have top shoots and roots. Replant the sections at the same depth as they grew before and water well to settle the soil and eliminate air pockets. Water as needed to keep the soil slightly moist until the plant is re-established. You can make almost any sized divisions depending on how many new plants you want to have. Broken top pieces will also root if stuck into the ground.
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