The best way to tell if your spider plant offset is ready to be planted is to check the roots. Spider plant roots are tuberous and develop from a node into a cluster before the plant is even exposed to soil or water.
Although they appear dry and tough to the touch at this early stage this will quickly change as soon as the plant has consistent access to moisture.
It’s worth saying now that there’s no great rush to pot up spider plant plantlets whilst they remain attached to the parent plant.
Separating the plantlets too soon from the parent increases the chance that the young plant won’t be able to support itself during the early stages of growth.
Waiting until the roots on the plantlet grow to at least 5mm in length before planting will allow the plant to adapt to its new surroundings quicker.
Although having said that it’s likely that when growing in a natural habitat the plantlet will begin to develop its root system rapidly as soon as the node comes into contact with a suitable growing medium.
If and when you do want to create new spider plants there’s a couple of methods that you can choose to propagate them.