Sedums and other succulent plants make colorful and impressive ground covers. People often want to know how long it will take their new plants to fill in an area.
As a general rule of thumb, ground covers will spread an inch a month. This means that if you space your plants 6" apart it will take 6 months to get a solid mat of growth. 12" apart will require 12 months and so on.
So, to figure out how many plants you need to cover an area you first need to figure out the area's square footage by multiplying the length by the width.
Then, remembering the rule of thumb for ground covers, use the chart below to determine your multiplier according to your desired plant spacing. Now multiply the your square footage by your multiplier to get how many plants you will need.
For example if you have a 2' x 10' (20 sq ft) area that you want to cover with sedums, and you want to space the plants 12" apart (12 months for solid foliage), you will find the multiplier for 12" spacing (1.00) and multiply it by your square footage for a total of 20 sedum starts that you need (1.00x20=20).