Learning when and why to use these soil amendments will improve your gardening results and save you money.
Deciding which soil amendments are right for your garden can seem daunting becausesoil is ever-changing.
Some nutrients are removed and others are replaced as plants grow.
Credit:Marty Baldwin
Moisture levels change, and pH can shift over the seasons.
What is a soil amendment?
Why Add Soil Amendments?
Credit:Dean Schoeppner
Or you may be looking to replenish certain plant nutrients organically.
Before adding amendments to your garden,a soil testis a good idea.
Compost is the decomposed remains of plant material that was once alive.
Think of leaves, grass clippings, bark, kitchen scraps, and straw.
When hot composted, the resulting material has very few weed seedsthe heat kills them.
If you dontmake compost yourself, look for it where you buy potting soil.
Adding compostboosts the amount of organic matterin your soil.
Lots of organic matter improves drainage while also helping the soil hold on to plant-available water better.
It adds fertility to all soils.
While compost clearly is a versatile soil amendment, theres no need to go overboard.
A 3-inch deep layer can be worked into the soil when creating new garden beds.
Then, a yearly addition of 1 to 2 inches is more than sufficient.
More important than the critter of origin is that the manure has been composted or allowed to rot.
Fresh manure can burn or kill plants and introduce bacteria into your garden that cause human diseases.
Given time to decompose, manure becomes an excellent soil amendment similar to compost.
Aged manure, often called well-rotted manure, raises the soils fertility and increases the soils organic matter.
Drainage and pore space are also improved.
If youve seen hugetomato plants with barely any tomatoes, excess nitrogen is a likely reason.
Lime
You canadd lime to garden soilsto neutralize acidity, raising the pH from acidic to neutral.
The pH scale runs from 0-14, with 7 being neutral.
Soil pH affects how plants take up nutrients.
Most garden plants do best in the 6.0-7.0 range, where many nutrients are at their peak availability.
Pelletized lime is available in bags and easily spread in the garden.
Unless you have a farmer neighbor offering it for free, skip the product known as ag lime.
Its intended for large fields and spreading by powerful machines and often has large clumps.
Sulfur
Some soils have an alkaline or basic pH, meaning a value greater than 7.0.
This will help bring down the pH to make more soil nutrients available to plants.
When purchasing sulfur, look for the product called elemental sulfur.
Many other sulfur products are sold, some of which contain insecticides.
Sulfur wont immediately lower the pH, so expect results to take a year.
Apply it in early spring or autumn and work it into the soil.
Dean Schoeppner
5.
Perlite
Perlite is mined from volcanic material and then heated in a furnace, where it expands like popcorn.
Its white and fluffy and feels a bit like Styrofoam.
Youll likely find it in potted plants you buy from the nursery.
Use perlite to keep soil in pot fluffy and loose, improving drainage and air circulation.
It’s also useful for propagating cuttings.
Vermiculite is gray and flaky and a common ingredient in seed-starting mixes.
Choose vermiculite to aid in water retention for potting soil, especially when starting seeds.
