mixing compost and soil to increase the ph by adding amendments

How Do I Make My Soil More Alkaline: what to add

When you’ve been gardening for a little bit and have gotten a handle on the basics of seeds starting, transplanting, etc. it’s time to delve a little bit deeper. Increasing your knowledge about the soil is the most important thing you can do. Soil Ph is important – in this article, we’ll discuss the question, how do I make my soil more alkaline?

Soil gives life to plants and if we don’t understand what’s going on beneath the surface, we will only reach a certain level of success in the garden. One of the easiest concepts to understand and apply is soil pH.

Most plants prefer soil with a neutral pH around 6 – 7. However, when you go beyond the acidic or alkaline environments, some plants won’t be able to access essential nutrients in the soil. This means that even if you add heaps of compost, the plant won’t be able to take advantage and uptake the nutrients. If your soil is above a pH of 7, it’s alkaline.

There are some plants, however, that thrive in soils with extreme pH. Based on the results of your soil pH test you can decide whether you want to only plant things that will do well in those conditions, use an alkaline amendment to make acidic soils neutral, or use an acidic amendment to make neutral soils alkaline for specific plants.

Whatever you do, make sure to not overdo the amendment and monitor the pH of the soil throughout the year.

How do I know what pH my soil is?

The easiest way to know what pH your soil is at is to pay attention to what plants are naturally growing there. These are called indicator plants because they tend to indicate the soil conditions.

Some wild plants that indicate alkaline pH include wild carrot, goosefoot, white mustard, nodding thistle, and true chamomile.

Asparagus stems on a wooden chopping board
Asparagus likes really alkaline soils – pH 6.0 to 8.0

If you want a more precise approach, you can either use pH indicator strips or a digital soil pH tester. I like to use paper pH strips because they’re so cheap and easy to use.

The pH test kits also work great and give you a more precise reading. I find them a bit annoying, however, because you have to calibrate them before each use so it’s not super convenient for quick soil tests. Plus if you’re only using it for a quick test once a year, the paper strips are much cheaper.

Depending on your needs, you might get by just looking at the plants naturally growing in the soil. If you don’t feel super confident in plant identification or aren’t seeing any indicator plants, then opt for the paper pH strips.

If you need an exact pH for whatever reason, the only tool that will give you a precise number is a digital soil pH tester.

How do I make my soil more alkaline?

To make your soil more alkaline, add in alkaline amendments when you prepare your garden bed. This process is usually done in the spring and you can add these amendments when you mix your compost into the soil.

You can use limestone, hydrated lime, or wood ash to make your soil more alkaline, the amount you need to add depends on how much you need to change the pH and how fast you need it done.

Regardless of the number of amendments you want to use to make your soil more alkaline, you’ll work them into the soil the same way. Before you begin planting your bed mix in the liming agent, compost, and whatever other amendments by gently tilling it into the top few inches of soil.

Gradually add in whatever amendment you decide to use and frequently check the pH of the soil. It’s better to add more later on than to add too much at the beginning. I normally check the pH of my soil about once a year. Then when I prepare my garden beds in the spring, I plan accordingly.

I also recommend adding it in with lots of compost since it will help balance out the effects of the amendment. Plus, compost is plant food and gives you better soil, so why not?

Which amendments can I add to make my soil more alkaline?

Alkaline soil means it has a high pH (acidic soil has a low pH). This means that you’ll need to add amendments that have a very high pH. The most common soil amendment to raise the pH is limestone. Depending on how fast you need it to react, you have a couple of options.

Agricultural limestone can be incorporated into the soil but needs time to start working. If you’re looking for a quicker fix, hydrated lime works faster, but it is much easier to over-lime.

limestone quarry face
Limestone is a great amendment to increase soil pH

Another material that can be used to raise the pH is wood ash. This is one of my favourites because it’s a gradual process and hard to overdo. In addition to raising the pH of your soil, it also has some fertilising benefits.

How much amendment should I add?

The amount of soil amendment you should add depends entirely on how big a shift in pH you need, your soil type, and the type of amendment you’re using.

It can appear to be quite complicated to calculate the amount of amendment needed. But usually, the product label will advise how much should be added. Once you have made one application you can re-test the soil pH and either add more or leave it.

Why would I want to make my soil more alkaline?

Gardeners might want to amend their soil with a liming agent to raise their soil pH for several reasons. The main reason is that the soil is too acidic, so you need an amendment to raise it more to a neutral pH.

The other main reason is that you are growing plants that are naturally adapted to alkaline soils and will thrive in high pH.

Just be aware that if your soil pH becomes too high you might prevent anything from growing by preventing the uptake of nutrients.

Which plants prefer alkaline soil

When soils become too alkaline it can inhibit the uptake of minerals like iron and phosphorus It would be impractical for me to outline all the alkaline-loving plants that exist. So here are a few of my favourites to get you started:

lavender flowers on a green grass background
Lavender is a good indicator of alkaline soil
  • – Lavender and other aromatic plants like rosemary, oregano, and thyme.
  • – Flowering shrubs like honeysuckle, lilacs, hydrangeas, and buddleias.
  • – Some common vegetables like broccoli, cabbage, kale, and asparagus prefer neutral soils but will also benefit from alkaline soils because they reduce the chances of diseases like club rot.

This is by no means an exhaustive list. If you already have alkaline soils or are determined to make your soil alkaline, these suggestions are a good place to start.

Key points

Have you been giving your plants all the love but they’re still not thriving? It might be because the soil is the incorrect pH for them.

Are you starting a garden bed and want to know how to prepare the soil? Checking the soil pH will give you a good idea of what else you need to add when you’re mixing in compost.

Want to grow specific plants that only thrive in alkaline soil? Use amendments to make the conditions perfect for them.

There are lots of reasons why you might want to make the pH of your soil more alkaline. Luckily, it’s a simple and accessible process that will have a huge impact on the success of your garden. Now choose which alkaline amendment is right for you and get to work.