How to Improve Your Garden Soil
Updated: Oct 21
If you are reading this chances are, like me, you have less than ideal garden soil. The health and growth of our vegetable garden has much to do with the nutrition and density of the soil these plants are growing in! Gardening in Alberta has its challenges with the rocky clay soil we often find when we dig into our land. Lets take a look at some ways we can improve our soil and grow more bountiful vegetable gardens.
Plants require three main essential nutrients for growth; nitrogen, phosphorous and potassium (potash). Fertilizing (see Figuring out Fertilizer) is one way of providing garden vegetables with these nutrients but a superior option is growing vegetables in soil that already contains these! Obtaining this coveted nutritious soil will likely require some work on your part.
In addition to providing nutrients for our plants, we need to take a look at the consistency and texture of our soil. Ideally we want a loose, aerated soil but at the same time soil that has the ability to retain moisture and nutrients.
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If you are building a new garden or a raised bed, a great starting ratio for your vegetable garden soil can be made up from 1/3 topsoil, 1/3 peat moss and 1/3 compost. If you are using a high quality compost this mix will give you nutritious, loose soil with good drainage.
When you are working with your land's original soil, discard all rocks, roots, sticks and hard lumps of clay. Do this by raking over the soil as you work in it. Use a garden rake and pull large pieces to a corner where they can easily be picked out and discarded.
Before you begin amending your garden soil I highly suggest doing a simple soil test! This will give you a baseline and will be encouraging once you begin to see improvements. When purchasing a test kit, make sure it contains tests for pH, nitrogen, phosphorus and potassium levels. Also check how many tests your kit can perform. Some are single test whereas many can test a number of times. Here is a link to a test kit available from Amazon that tests for pH, nitrogen, phosphorus and potassium and contains 40 tests. I suggest testing your soil twice a year, once in the spring and again in the fall.
The greatest favour you can do for your garden soil is adding compost! Adding compost to soil improves the texture of all types of soil from clay or silty soil to sandy soil. As well, a good quality compost will contain all of the essential nutrients for your plants. If you are not already composting I highly recommend starting! Why not turn your household organic waste into nutritious food for your plants! All you need is a little space outdoors somewhere, time and some organic waste. For a guide to composting check out 6 Composting Tips. If you are unable to compost, you can also purchase bags of compost from your local garden supply store.
Once compost has gone through is breakdown cycle it is rich in all three main nutrients required by plants; nitrogen, phosphorus and potassium. Many garden vegetables prefer slightly acidic soil with a pH of 6.5 to 6.8. By adding compost to your garden regularly you can, over time, drop the pH of your soil. Compost works well to help moderate soil pH levels.
Adding compost to clay soil loosens the soil and allows for improved drainage. At the same time, adding compost to sandy soil will help the garden soil to retain moisture. Proper drainage is important to all garden vegetables and makes adding compost an ideal improvement for drainage issues.
Peat moss is an organic material harvested from bogs. It is similar to compost in that it loosens garden soil and improves drainage. Unlike compost, peat moss does not contain any nutrients important to plant growth but rather improves soil's capacity to retain nutrients and make them available to plants.
Peat moss can be purchased in plastic bales from Amazon or any garden supply store for a relatively low cost.
Worm castings contain beneficial microbes and bacteria and are great for your garden in a similar way to compost! In addition they contain humic acid which aids in plant nutrient absorption. They improve soil's ability to retain moisture and nutrients while keeping soil aerated with good drainage. If you are up for it, raise your own worm farm and break down your compost quicker!
Adding sand to clay soil is controversial. The danger of adding sand to your soil is that sand mixed with clay can create a concrete like mixture, resulting in the opposite of what we are trying to do with our soil. For this reason consider adding more compost or peat moss instead of sand to break up clay soil. At the same time, saying this, I experimented with adding sand to my soil as we had an unused pile of sand on our property when we moved in. I did feel like the beds I added sand to had a looser and improved soil texture that my root vegetables especially seemed to thrive in.
When I tested my soil this fall I found there was almost no phosphorous! Phosphorous is essential for good root growth in plants. One way to provide phosphorous is to add bone meal to the soil. If you find your soil is low in phosphorous here are some bone meal options available from Amazon.
Amending Soil pH
You can have what feels and looks like perfect garden soil but if it is too alkaline or acidic your plants will still struggle to grow. For acidic soil, look at adding lime. For alkaline soil add sulphur. Over time compost will also aid in correcting alkaline soil but this will only be seen after a year or two with repeated compost applications. I added this sulfur to my very alkaline soil and noticed a big improvement in my garden vegetables growth!
My first year of gardening on our acreage (2017) my beets were too small to bother cooking and all my carrots were tiny. Nothing was growing well. Since working the soil over the past few years I have seen major improvements to our plants growth! Gardening has become so much more fun as I see our plants thrive with the work my husband and I have put in to developing the soil! I feel I still have quite a ways to go to get it where I want to be but change is happening and in the right direction. Each year the soil improves a little more!
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