To fill the hole, mix the soil you removed with soil amendments. I used a soil conditioner that I had bought, but you could use compost, instead.
Don't think that filling in the sides of the hole is a mindless activity, requiring that you merely shovel dirt in till you've reached the top. What you have to keep in mind is how the soil will settle. "Settling" simply means that the soil will compact, after air pockets work their way out.
Excessive settling will leave a donut-shaped depression around your plant (you'll come out for a look one day and wonder, "Gee, where did all the soil go?"). You can avoid excessive settling by filling the planting hole in such a way as to beat nature to the punch in removing air pockets. The idea is to remain in control of the soil level.
To achieve a controlled settling:
- Tamp the soil as you place it in the hole, in stages.
- Watering the soil lightly also helps remove air pockets.
After filling the hole, the rootball of the shrub should protude slightly above ground level, to promote good drainage. The need for drainage explains the second part of the rule of thumb mentioned earlier, namely, that the depth of the planting hole should be less than that of the rootball. If you were to dig the planting hole too deep, the base of the shrub's trunk might end up below ground level, after the soil settles. The resulting poor drainage fosters plant diseases.
In Step 8, let's consider shrub selection.
