Planting time is finally here (except in Minnesota -- haaaaaaaaahh!!). So how many of you think it's a good idea to amend your soil with peat moss and stuff before planting anything? It sounds right, so it has to be right. Right?
Not so fast, Grasshopper. Sometimes amending is good and sometimes it's useless or harmful. It all depends on what you're planting, how big it'll get, and how many things you're planting.
Amending the soil (especially with lots of organic matter, like peat, composted cow manure, chopped leaves, and kitchen compost) makes sense when what you're planting has a relatively confined root system -- like a flowering annuals and perennials, vegetables, herbs, and bulbs. It also makes sense if the plants need acid soil, like blueberry, azalea, or heath, and your soil is alkaline, or if you're preparing to plant a new garden bed that will contain groups of the same kinds of plants.
On the Other Hand... But what if you're planting a crepe myrtle that will get 30 feet tall, an oak or maple that will get 60 feet tall, or a cherry that spreads 25 feet wide? Then it's a different story, because the roots of these big plants will spread about as far as the branches. So you gotta ask yourself -- how do I feel about digging a hole about 30 feet wide and amending all that soil? Am I totally loving the prospect?
Personally, I'd rather drink this here beer. (Of course, that's my first option always.)
As a rule, don't amend the soil when planting a tree or a shrub that gets big. Why? because most of its roots will grow beyond the hole where you added soil amendments. Instead, focus on getting the tree or shrub off to a good start by digging a hole that's three times the width of the root ball -- but no deeper. Place the root ball in the center of the hole and backfill around it with the original soil you just excavated. The roots will appreciate the loosened soil and quickly adapt to the soil type of the surrounding yard. Then water and add mulch over the top.
But, But, But.................
"What should I do if I'm planting a tree or big shrub and my soil is nothing but crummy red clay, sand, gumbo, or rocks? My Mom said to add peat moss! You must want my tree to die, you big, mean Grump!"
No, I don't. I want your tree to live! So if you find yourself in a desperate situation like this, look around at the native trees that planted themselves in the same kind of slop that you have and are thriving anyway. Then plant one of those.