The soil in your garden is one of the essential parts of sustainable growing practices. Knowing what your plants need and how to fix this within your soil will make all the difference in your growing success.
The best way to determine what kind of soil you have, if not already apparent by looking at it, is by doing a soil test. A soil test will help you determine if your soil lacks any major or minor nutrients, what salinity levels you have, and which plants would fit best in your environment.
How to do a Soil Test:
To perform a proper soil test, you will need some essential tools. You will need an airtight container, an accurate scale or balance, a sampling tool (unless you are testing soil already in its pot), and some distilled water if you are testing the soil in the pot.
The first step is to take your soil out of its pot unless it is already loose soil. If it is loose, grab about two handfuls of soil and test it as is.
Next, level out your sample with the sampling tool (or a knife if no tool is available). It does not need to be perfect; close enough will do since you are only doing this for accuracies sake anyway.
Finally, weigh the soil using weight over volume. The proper volume for a home scale is about 100 milligrams of soil per 0.01 kilogram or 100 grams. Record both the weight and volume so that they will be in the same units when you receive your report. You will not have to worry if you do not have an accurate scale at your disposal. Just record the weight of your sample in its container to the best of your ability.
An independent laboratory will analyze your sample for macronutrients (NPK values), moisture, pH, and cation exchange capacity (CEC). Once you receive the lab report in the mail, make sure to take all of the information with a grain of salt. No matter what the report says, your plants will thrive best in healthy soil with a pH of 6.2-7.0 and CEC between 50-100. The numbers are just there for general reference.
Specifics about Testing:
Many different nutrient deficiencies can happen to your plants, whether you are growing outdoors or indoors. Before you start dosing your plants with nutrients, it is essential to determine where they are deficient. The best way to do this is by doing small soil tests on your plant’s leaves between their internodes.
To perform a leaf test, grab about 10 healthy leaves from the top of the plant and place them in a Ziploc bag.
Then, use your fingers to crush the leaves into a fine powder until they are impossible to see with the naked eye. This is an easy way of breaking down their cellular structure, which will allow for testing without damaging the roots or stems of the plant.
Lastly, retrieve your lab test kit and test for deficiencies according to the package directions. To perform a tissue test, take about 10 leaves from the base of your plant and crush them as well.
Finally, place the crushed leaves into a container filled with distilled water and wait around 15 minutes. If you see any discoloration in the water, it indicates a deficiency in one of the significant nutrients. To determine which nutrient is in short supply, you will have to research online or consult your local gardening store.
The different soil types:
When you are testing your soil, it is essential to know what kind of soil you have. There are a number of different types of soil along with combinations of them. We will discuss each of these types and their effects on your plants as follows:
1) Sand: This is the best soil type for growing plants because it drains quickly and does not hold onto too much water. It also has a high cation exchange capacity (CEC) and nutrient holding capacity, perfect for heavy feeders like tomatoes.
2) Silt: This soil type is not very common since most of the world’s rivers have changed the natural silt to sand over time due to erosion. Its main drawback is that it does not hold onto nutrients very well and can become nutrient-deficient over time. It does, however, have a good CEC and drainage factor.
3) Fine Clay: This is the best soil type for growing plants because it holds onto water, nutrients and stores cations (positively charged ions). The downside to clay soil is that it can become nutrient deficient over time, although this can be fixed with a generous dose of compost or other organic matter.
4) Loam: This type of soil is the ideal combination of all the factors mentioned above. It drains well while holding onto reasonable amounts of water and nutrients. It also has a good CEC to store lots of cations.
5) Peat: This soil type is very acidic, low in nutrients, and has poor drainage. However, it does retain water very well, which can be helpful for potted plants that need to stay moist all the time. Its main benefits are its organic matter content and nutrient holding capacity.
6) Compost: This type of soil has a very high nutrient content and stores a lot of water. Its main drawback is its lack of a CEC, which means it does not hold onto cations well.
7) Soilless Mixes: These mixes are typically used for hydroponic systems or when growing outdoors in open fields. They are deficient in nutrients and retain almost no water. They are also entirely lacking in organic content.
8) Peat-lite Mixes: These mixes have many properties as peat but drain better since they have more sand mixed into them.
9) Topsoil or Garden Soil: Topsoil is not suitable for growing cannabis due to its heavy clay content, although garden soil has shown to be an effective medium. It drains well and retains water very well but can become nutrient deficient over time.
10) Planting Mixes: These are typically used in container gardening or other restricted root systems where the roots cannot spread out. They are high in nutrients and retain water well, but otherwise are very similar to most soil types.
This guide should give you a good idea about selecting your soil and preparing it for cannabis, whether it be indoors or outdoors. While there is no perfect type of soil, most soil types can be effective with proper amendments and techniques. For the healthiest plant possible, I recommend fine loam soil that holds onto the water but doesn’t hold too much.
Leave a comment below if you have any questions or would like to add anything. Thank you.