Sedums, like many perennials, can be planted any time of the year. If the weather beckons and you feel the urge to plant, then it is a good time to work sedums into your garden. Ensure that the ground is not frozen, however, and that you can get water to newly planted sedums.
Spring is a good time to plant sedum. Nothing exists to keep you from spring gardening, and sedums planted during spring will readily take to your garden, showing dramatic growth very quickly. If the earth is saturated from heavy downpours, however, do not plant sedum or anything else. Use the best soils when planting, and fertilise newly planted sedum.
You can plant sedums in the summer without problems. Sedums, which can grow fairly large, like hot, sunny, dry places in a garden. Watering after planting and then monitoring watering afterward is crucial for summer sedum-planting success. Do not plant a sedum in a site that holds water or stays moist for long periods of time.
Autumn is a fine time to plant sedums and allows them to get a jump on next year's growth. The air temperatures may fall during autumn, but soil temperatures that are still warm encourage root growth. When planting in autumn, look for healthy sedum roots; they should be white to light brown and not tightly bound against the edge of their pot. You should be able to see plenty of soil and roots evenly distributed throughout the root ball. No roots or black roots indicate a plant with problems that will prevent it from living through the harsh winter months. If you miss the window of opportunity to plant in autumn, that is OK because well-rooted sedums in pots can survive through winter and into spring.
With its frozen ground, winter is the only exception to the plant-sedums-anytime rule. If you cannot dig into the ground, you cannot plant because a sedum needs a hole twice the diameter of its pot and as deep as its pot.
Watering sedums thoroughly during winter is important even if it will rain. Watering forces out air and compacts soil tightly around the roots.