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How to Assess Your Garden Soil

Assessing your garden’s soil is just one of the factors that you need to consider when getting to know your garden prior to planting.

You will need to assess the pH, texture, moisture retention and organic content of your soil to figure out what plants will do best in your space or what you can do to improve your soil.

That being said, when I started my current garden, I only assessed its texture to find it was mostly loam (best soil ever, lucky me!). I didn’t do any pH tests or check how many earthworms were living where but in hindsight, these would probably have helped save some of my poor plants. For example, I ended up almost killing not 1 but 2 hydrangeas due to planting them in super alkaline soil and scorching sun! Ouch!

Another reason why you should assess your soil is to avoid surprises and to know how to enrich/improve it for certain types of plants.

Here’s how to assess the basic parameters of your garden soil:

Assessing your soil’s pH:

For precise values, there are numerous pH testing kits available. For a basic home experiment (which I’ve found to be more than enough!), you need some soil + vinegar + baking soda.

Take some soil in a container and add 1/2 cup of vinegar. If it fizzes, it means your soil is alkaline (since the acid ie vinegar has reacted and created bubbles, when coming into contact with your alkaline soil). If it doesn’t fizz, take some soil in a separate container and add half a cup of water and mix this mixture. Then add 1/2 a cup of baking soda. If it fizzes, this means your soil is acidic.

If it didn’t fizz with either of the above, it’s neutral. Plants will best absorb nutrients when the pH is between 5.5 – 7.5. Anything below this is extremely acidic and anything is extremely alkaline causing both deficiencies of some nutrients and toxicity of others.

When to check your soil’s pH and why this is important

You should check your soil’s pH not just when starting a new garden but also regularly throughout the year. The best time is usually autumn and at least 8-12 weeks after adding compost/soil improvements. The plants are entering their resting phase and you will also get plenty of time after testing in autumn, to make improvements if required. Plants can either die or fail to give you their best if the soil isn’t ideal – this can prove quite costly so make sure you test your soil and ensure you are either adding the correct improvements or choosing plants to suit your existing soil.

If you get into the nitty-gritty of this pH business and want more home-based techniques to test your soil, check out this fabulous article by preparednessmama.

And of course, here’s Gardener’s World take on this:

Assessing your Soil’s Texture

When it comes to assessing what kind of soil you have in your garden, this is by far the most important one. I did not want to dig into gardening encyclopedias so all I did was watch a few videos and apply that knowledge to my garden. Your garden may not have the same type of soil throughout so remember to test a few areas. Luckily, I had all beds filled with loam, possibly since these areas had been improved but the lawn area was slightly more compacted soil – I did eventually have to improve this.

Various soil textures have different rates of water drainage and thus moisture as well as nutrient retention. The more compacted your soil, the lesser the drainage, etc. Some plants like well-drained soil whereas others prefer slow-draining soil (rarely the latter though). So, sadly, you do need to know this before you begin planting.

Here are the best videos that tell you how to assess your soil’s texture:

Assessing your soil’s Moisture Retention

Funny story – I killed off a few potted plants by adding horticultural grit to the base of the pots but didn’t check whether there was drainage when I watered them. It only became apparent when they started looking rather sad – to the point of no return. You will often hear about adding pebbles/grit to improve drainage, etc. It’s always critical to check this once you’ve filled your pots. Another common mistake is that people place their pots directly on the ground thus blocking off their drainage holes. Either get ‘pot feet’ or some form of planters designed in a way that certain areas at their base are raised to allow drainage.

When it comes to testing soil drainage, here’s how to test it: Dig a hole around one foot wide by one foot deep. Next, fill it with water and let it drain fully. Fill it to the top with water again and immediately turn on a timer. The amount of time it takes tells you how fast-draining your soil and what plants it can best support:

0 – 4 minutes: Fast-draining soil – This should be just fine for most plants but you may need to add more soil/improvement to help retain nutrients.

5 – 15 minutes: Good draining soil: Ideal for most plants.

16 – 60 minutes: Slow-draining soil, not ideal for most plants. If the water drains at 1 inch per hour, you’ll either have to make improvements or chose plants that like sitting in boggy areas.

More than 6 hours: Poor-drainage, you’ll definitely need to make improvements to your soil or chose the few plants that can do well in this situation.

I don’t have much experience with extremely poor draining soil as above so I’ll stop there but if you look for plants that thrive in boggy conditions/clay soil, you’ll be pleasantly surprised at the number of options!

Assessing your soil’s Organic Matter

Truth be told, I didn’t test for this specifically and my plants have done very well. Probably because I improved most of my soil with fresh compost and manure. Various sources give various ways of testing soil organic matter but the more critters and earthworms you have the better. Good Housekeeping has an excellent list of ways to check for these if you’d like to dive in deeper.

If, like me, you want a short, to-the-point, pointer, here goes: Three earthworms per 6 inch of dug up soil are satisfactory, 6 are excellent. Dig another 6 inch hold and look into the hole for 4-5 minutes. Less than 10 active species means your soil doesn’t have enough activity and you need to improve its organic content.

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