How To Amend Soil
A Guide to Soil Preparation
What follows are general rules or guidelines for preparing any garden for planting.
Preparing a garden bed before you plant will greatly improve your gardens performance, and promote healthy vigorous growth from any plant you choose.
Most often preparing for planting is done in the spring, and involves tilling or turning the ground, and at the same time adding generous amounts of organic material and some type of fertilizer.
The goal is to break up and loosen earth that has become compacted over time, and to replenish vital minerals and nutrients.
Conditioning, or reconditioning the soil as it is sometimes called, is best done after the winter rains or frost have passed, but before the summer growing season has started.
However, soil prep can be performed at any time that the ground is not too wet or frozen to till.
A clay or heavy clay soil, will greatly benefit from the addition of organic material, and it’s almost impossible to add too much.
Clay, because of its particles size and shape, tends to become compacted, and so will drain slowly or not at all.
Also, the heavy compact nature of clay tends to prevent air from reaching the roots, which will slow plant growth.
Tip: As water passes down through the earth it draws air (oxygen) behind it. Soils with little or no air tend to become "sour" as oxygen is a necessary ingredient for biological activity.
One of the benefits of clay in the garden is it's natural moisture retention properties.
By combining a generous amount of organic material with clay, you can off set it's tendency towards compaction, improve drainage, and allow the nature of clay to help maintain moisture in your garden.
A good ratio of clay soil to organic material is roughly 50/50.
The picture below shows examples of three soil types. On the left is a sandy soil with organics added. Center is a healthy, rich compost. And to the right is a heavy clay soil that will need to be amended.
Sandy soils are the opposite of clay and generally drain too fast, and so are unable to hold onto any nutrients long enough for a plant to use them.
Organic matter helps to hold onto water and nutrients, and as with clay, it’s almost impossible to add too much.
A higher ratio of organic material to sand is a good option, as the organic matter tends to break down faster due to faster drainage (more oxygen).
Clay and sand are at the opposite end of the soil type spectrum. Most gardens will be somewhere in the middle. The organic material available to you may depend on what region of the world you live in.
However, regardless of soil type, the addition of organic material will greatly improve your garden’s performance.
Potting soil is usually some combination of the above list and may have little or no actual “dirt” in it.
Organic material helps to maintain moisture content levels, increases biological activity, and helps to prevent soil compaction.
Tip: When adding organic matter to planting beds or gardens, add at least 2 inches on top of the bed and work in evenly to a depth of 4 to 6 inches.
If adding 2 or more inches of organic material would raise your beds higher than you’d prefer, you’ll need to remove some of the existing soil first.
Don’t worry, your garden will love you for it.
Tip: When preparing for planting always till (loosen) the earth before you add organic matter or fertilizer. Till no less than 4 inches and no more than 12 inches deep.
3 Steps to a Healthier Garden
1. Break up and loosen the soil (using a shovel or spading fork), to a depth of between 6 to 12 inches deep.
2. Level the bed a little, and add 2 or more inches of organic material, then work in evenly (mix) to a depth of about 4 to 6 inches.
3. Again, level the bed a little, then sprinkle or add a granulated-slow release fertilizer of your choice on top and "scratch in" or lightly till to about 1 to 2 inches deep.
This method tends to simplify the process of preparing a planting bed, and allows you to save time and energy for other gardening activities.
Tip: All depths listed above are Rule of Thumb measurements. In general all plants respond well to the above system.
If most of the plants you'll be growing tend to be shorter (1 to 2 feet high), you won't have to till as deep (about 6 to 8 inches).
Taller plants will have deeper root systems, so tilling deeper in that case will be helpful. In general though, tilling deeper than 12 inches is an unnecessary use of time and energy.
Adding organic material around existing or established plants is not difficult. Till in to about 2 inches if close to a plant, and a little deeper if further away.
Simply try not to disturb the roots too much, and always water when you're done to settle any roots that may have been disturbed.
Good Luck and Happy Gardening!
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