Have you ever wondered how to get higher yields and healthier, more abundant flowers from your garden? It’s simple: test and amend your soil before planting.

Many people skip this step when getting started. We didn’t test the soil before planting our first plot, and the garden didn’t do well because it was too alkaline, and we didn’t amend the soil well enough given its high clay content.

You may be astonished at how much better your garden does by simply adjusting the soil pH to the correct level. Though, testing for both nutrients and pH provides more useful information.

Some soil test kits only measure pH, but there are test kits that measure the “macronutrients” nitrogen (N), phosphorus (P) and potassium (K), as well.

Other macronutrients are not tested for, but include: calcium (Ca), sulphur (S), magnesium (Mg), carbon (C), hydrogen (H) and oxygen (O).

Carbon, hydrogen and oxygen exist in the atmosphere and are considered structural elements.

For a complete analysis of micronutrients in the soil you will need to send soil samples to a lab, though, for the home gardener, this is not really necessary. Simply amending your soil with compost will likely provide the necessary micronutrients.

Knowing the nutrient levels in the soil is useful for deciding how to fertilize most efficiently and for deciding which soil amendments to apply.

Testing the soil will give you the confidence to grow a successful garden. Confidence based on knowledge almost guarantees success.

Drainage Test

If you intend to plant an in-ground garden, conducting a soil drainage test is a good idea.

A drainage test is easy to do and provides useful information. It will help you to determine what soil amendments to use and how much of the amendment may be required.

The only tools you need are a shovel, a clock and a bucket.

To conduct a drainage test, simply:

• Dig a hole the depth and width of a spade (about 12 inches)
• Fill a three gallon pail with water and pour it into the hole
• Note the time it takes the water to be absorbed

In well-drained soil the water should be absorbed in 15 to 30 minutes. If the water is absorbed faster than 15 minutes, the soil doesn’t retain water well enough. Conversely, if the water takes longer than 30 minutes to be absorbed, the soil doesn’t drain well enough.

Soil that drains too quickly likely contains a high proportion of sand, while soil that doesn’t drain well likely contains a high proportion of clay.

The Mason Jar Soil Test

The jar test will help determine the texture or components of your soil. Texture is the relative percentages of sand, silt and clay in the soil.

Knowing the composition of your soil helps you to select the correct amendments when amending the soil.

There are two ways to take samples for the jar test. The first is to take several samples from around the garden and mix them together in a bucket before doing the soil test. The second is to test samples from around the garden separately.

The second method more accurately defines the soil texture overall; you just need a few more jars so all the tests can be done at the same time.

This video by Midwest Gardener shows how to do a Mason Jar Soil Test.

How to do a mason jar soil test:

1. Dig the samples going down about eight inches into the soil.
2. Remove any roots, mulch or stones.
3. Mix the samples together in a pail, or test each sample separately.
4. Fill about one third of a quart size mason jar with soil.
5. Add a teaspoon of dishwashing soap (this will help the soil particles disperse and settle).
6. Add water to the jar leaving some air space at the top so that it can be shaken after putting the lid on.
7. Shake the jar for several minutes until all the soil particles are in suspension.
8. Set the jar aside for a couple of days to a week to let the particles settle.
9. Measure the different layers to determine the percentages of each component.

As the particles settle they will separate into layers with sand on the bottom, silt in the middle above the sand and clay on top.

Ideally, your tests would show that your soil is loam which is 40% sand, 40% silt and 20% clay. Unfortunately, chances are you won’t have a perfect loam, but that is what you are aiming for when you amend the soil.

How to Take Soil Samples When Testing for pH and Nutrients

When you test and amend the soil it’s an investment in future production; the large yield at harvest time is your return on investment.

You may be surprised at how easy soil testing is. The only items you need to take soil samples are:

• a stainless steel or plastic garden trowel
• a bucket
• plastic containers or zip lock bags

Make sure these items are clean so the sample is not contaminated. If you are going to do many tests, a soil core tool is useful to have but not necessary.

In order to get reliable test results, take a number of samples from the entire area in which a particular plant or crop will be grown.

If you have observed previously that plants don’t do well in certain spots or you intend to grow plants that require specific conditions, like blueberries, test and amend the soil in these areas separately.

It’s easy to check the recommended pH for each type of plant you intend to grow. You will find the pH for vegetables here and the pH for flowers here.

There are two ways gardeners commonly take soil samples.

The first method is to take a number of samples from around an area in which the same plants will be grown and mix them together before testing.

The second method is to test a number of samples from around the same area individually without mixing them together.

We use the second method as it provides a better understanding of the differences in soil conditions from one place to another. Using either method is better than not testing at all.

To get accurate results take the samples on a day when the soil isn’t too wet.

Taking samples and mixing them together before testing:

1. Scrape away any leaf litter or mulch applied previously before digging a sample hole.
2. Dig a number of holes in your garden area approximately 4 to 6 inches deep. The idea is to test the soil to the depth the roots of particular plants grow.
3. From the side of each hole take a slice approximately half an inch to an inch thick and put them in the bucket. Pick out any rocks and organic debris like roots.
4. Mix the samples together in the bucket and let the soil dry in the shade or at room temperature.

Taking samples and testing them individually:

1. Scrape away any leaf litter or mulch applied previously before digging the sample hole.
2. Dig a number of holes in your garden area approximately 4 to 6 inches deep.
3. From the side of each hole take a slice approximately half an inch to an inch thick and put it into a separate container. We use Ziploc bags.
4. Label each sample with a description of where it was taken from.
5. Pick out any rocks and organic debris like roots and twigs. Let the soil dry in the shade or at room temperature.
6. If using Ziploc bags, roll the tops of the bags down a bit and leave them open.

Using the Soil Test Kit

Test your soil pH in the spring before planting, and, while it’s not strictly necessary, testing for the nutrients Nitrogen, Phosphorous and Potassium (N-P-K) provides a better understanding of your soil.

Home soil test kits work well and are easy to use. Digital pH meters are convenient and inexpensive, but in our experience they are not as accurate as soil test kits.

Sending soil samples to a lab will provide the most accurate results, but it’s unnecessary.

All you really need to know about pH is that it is measured on a scale of 1 to 14 with 7 being neutral. Below 7 soil becomes acidic while above 7 soil becomes alkaline.

Ordinarily, a pH level between 6 and 7 will be fine for most gardens. A pH level of 6.5 is a good level for most gardens.

We are using the Rapitest soil test kit for demonstration purposes because it is easy to use. There are other soil test kits available where the testing procedure is done in a similar way.

In this video Kevin Espiritu of Epic Gardening shows how to use a Rapitest kit to test the pH of soil.

These are the steps involved in pH testing your soil samples using the Rapitest kit:

1. Add soil to the testing container up to the soil fill line.
2. Carefully open the pH capsule and pour the contents onto the soil.
3. Add distilled or pH neutral water up to the water line.
4. Put the cap on the testing container and shake the solution so that it is well mixed.
5. Let the soil in the solution settle out. Some soils will settle out quickly, but we found that our clay soil took several days to settle out. If your soil has clay in it, just give it more time to settle.
6. Compare the colour of the solution to the colour chart. It may not match exactly, but it will be close enough so that a fairly accurate estimate can be made.

In this video Kevin Espiritu of Epic Gardening shows how to use a Rapitest kit to test for nutrients in the soil.

These are the steps involved in testing your soil for nutrients using the Rapitest kit:

1. In a clean container add 1 part soil to 5 parts distilled water.
2. Vigorously mix the soil and water together for a couple of minutes.
3. Allow the mixture to settle. How long it takes to settle will depend on the type of soil you have. For example: sandy soil will settle more quickly than clay. If the solution has a residual cloudiness, it will not affect the accuracy of the test.
4. Select the appropriate testing container for the nutrient being tested for. Draw off some of the solution with the dropper provided; do not disturb the sediment.
5. Fill both the testing and reference chambers up to the fill line. Both chambers are filled to allow for discolouration in the sample caused by the soil.
6. Take the relevant capsule for the nutrient being tested for, and add it to the test chamber.
7. Put the cap on the testing container and shake thoroughly.
8. Let the colour develop for ten minutes or a bit longer.
9. Compare the resulting colour in the test chamber to the colour chart. Illuminate the sample in daylight but not in the direct sun.

Follow the same routine for each of the nutrient tests. We do the tests in the conventional order of Nitrogen, Phosphorous and Potassium or N-P-K.

Testing a Field or Market Garden

We added this short section to reinforce the importance or soil testing. Most successful farmers and market gardeners routinely test the soil before planting.

When testing a farm field or a large market garden for the first time, sending soil samples to a lab is a better idea than using a home soil test kit.

In our experience soil test kits are accurate enough to rely on for a home garden and are more reliable than pH meters. However, tests done by a lab are more accurate and comprehensive.

The lab will analyze the sample and give recommendations on how to amend the soil and on the type, amount and frequency of fertilizer to use.

Take multiple cores or subsamples going down to a depth of six inches for each test.  Mix the subsamples in a bucket. The lab requires a pint of soil per sample.

Make sure the samples sent to the lab are labelled with your name, mailing address, sample depth increment and sample identifier.

In this video Dr. Eddie Funderburg provides information on testing fields where large crops are grown, though for gardeners a home test kit will work fine.

Amending Your Soil

The type of soil amendments to use will depend on the type of soil you have. Some useful terms to know are:

• Soil fertility – the combination of nutrients in the soil and the pH level
• Soil texture – refers to particle size
• Soil Structure – how particles clump together into aggregates

A sufficiently aggregated soil is said to have good “tilth.” This refers to the moisture content, the rate of water infiltration, the aeration and the drainage of the soil.

Environmental factors affect tilth. Tilling and amending the soil and changes in the amount of moisture in the soil will change its tilth.

This is why farmers will not plough a field when it is saturated from rain or flooding. It would damage the soil structure.

The main soil types are said to be sandy, silt and clay. In the United Kingdom six categories are often used: clay, sandy, silty, chalky, loamy and peaty. In our area three types of soil are generally identified as clay, sandy and loamy.

Often soils don’t fit into these precise categories, and there is no need to get bogged down on a precise definition for the type of soil you have. Just having a general idea of the type of soil will do.

When tests show that your soil is too acidic, use lime to bring the pH level up; if tests show that your soil is too alkaline, use sulfur to bring the pH level down.

If existing plants show signs of a magnesium deficiency or lab tests indicate a deficiency, use dolomitic lime to raise the pH. Otherwise, you can use calcitic lime.

An obvious sign of magnesium deficiency is when leaves turn yellow while the veins stay green; a condition known as interveinal chlorosis.

As a rule of thumb do not exceed five pounds of sulfur or lime per 100 sq. feet of garden space.

Our garden plot tested alkaline, and we applied about three pounds of granulated sulphur per 100 sq. feet. The soil is clay based, and clay soils can often be a bit alkaline.  

Make sure to use granular or pelleted sulphur when lowering the pH. Do not use finely ground sulfur because you will have to wear protective gear to apply it safely.

That one application in the fall of the year brought the pH level from over 7 to just over 6 by the next spring planting season. The soil has been amended with organic matter over the years, but the pH has not needed to be adjusted since.

The amendments we use, mainly peat moss and compost, are acidic and help keep the pH level of the soil from becoming too alkaline, again.

If, however, your soil is more on the acidic side or neutral, adding acidic amendments will lower the pH even further. In this case you would add lime to bring the pH level up.

Organic soil amendments include:

• Composted kitchen waste, leaves and yard waste
• Composted manure
• Humus or leaf mould (plant material like leaf litter decomposed by micro-organisms in the soil)
• Sphagnum peat moss
• Worm castings
• Comfrey (use as green manure, turn the leaves into the soil during the fall)
• Cover crops, legumes, clovers, peas etc.
• Commercial top soil

Inorganic soil amendments include:

• Lime
• Sulfur
• Coarse sand
• Perlite
• Vermiculite
• Gypsum

Amending the soil aids water retention, improves fertility and develops the texture and structure of the soil.

How We Amended Our Clay Soil

Soil amendments can be mixed into the soil using a rototiller, but we always use a spade. If our garden plot was a lot larger we would use a rototiller.

It’s easy to overwork the soil with a rototiller which damages the soil structure. Also, beneficial organisms in the soil, such as earthworms, will suffer less harm if you use a spade.

A cubic yard of soil amendment will cover 100 square feet three inches deep. This is a space 10ft x 10ft. The garden plot we amended is about 20ft x 15ft or 300 square feet total.

After adjusting the pH of the underlying soil, we amended it with inorganic builders’ sand, which has a neutral pH, and organic sphagnum peat moss, which is acidic and helped make the soil less alkaline.

We spread a cubic yard of builder’s sand and three cubic yards of sphagnum peat moss on the garden and worked it in. As it turns out we didn’t use enough sand or we should not have used sand at all. The garden became badly compacted.

There is some disagreement among gardeners about using sand to amend clay.

 We should have used three times more sand to the amount of clay being worked up to create a sandy loam.

Other people say that you should not use sand at all. You should amend a vegetable garden each year using organic materials such as peat moss, compost and leaf mould.

That’s fine for a vegetable plot, but anywhere perennials or something permanent is to be planted another solution is required. Soil replacement is often the best solution in the long run; excavate the clay and replace it with good quality soil.

Over the years we’ve continued to add peat moss and compost, but we’ve never used sand again. One year we added coconut core, perlite and vermiculite. If we were to do it all over again, we would use leaf mould and peat moss.

The plot is sufficiently improved that after turning in a bit of compost each season it’s ready to plant.

The Takeaway

Once the soil has been amended and the crops planted, the fun begins. Actually, for us, the fun begins in the spring as soon as we put a spade in the ground.

Your neighbours will be amazed by your green thumb.  With the soil pH adjusted correctly the plants will efficiently take up nutrients, and the result will be a healthy high-yielding garden.

Flowers will be larger, healthier, more plentiful and longer lasting. And the vegetable garden will yield a larger crop.

Amending your soil is very rewarding.

You will feel a real sense of accomplishment when the harvest is done. From amending the soil to harvesting and eating the food, we enjoy the process from start to finish.

Your vegetables will taste so much better than store bought produce you won’t want to go back to it. After we finish off our own fresh vine ripened tomatoes, I more-or-less stop eating them until we grow more the next season.

The one negative side-effect of growing your own vegetables is that store-bought vegetables will forever disappoint.

There are few things more satisfying than a bumper crop of delicious, nutritious food and abundant, beautiful flowers.