Gardening Advice

Choose the Best Soil for a Vegetable Garden

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Growing your own vegetables is gaining popularity among Australians, as people are taking leaps towards sustainable living. You know what goes into it, so you can have clean produce and at the same time minimise your environmental impact.

The economic benefits of producing your own food also shouldn’t be ignored. Why rush to the store when you have all you need right there in your backyard? Not to mention how fulfilling it is to be able to eat veggies you’ve grown yourself.

All you need is some space in your garden or a few planter boxes, and, of course, high-quality soil. You want the best soil for your vegetable garden as all the nutrients from it end up in your food.

Read on if you:

  • Wonder what’s the best soil for a vegetable garden;
  • Wonder about the proper ratio of soil mixture;
  • Want to know how to improve the soil in your garden.

You’ll learn how to choose the best soil for your vegetable garden. This post will also shed light on how to go about veggies in raised beds.

Table of contents:

Soil nutrients for your vegetable garden

Fertile soil should have all the nutrients needed to support your plants throughout their life cycle. The three essential nutrients, that no fruit or vegetable can live without, are nitrogen, phosphorus and potassium. You might have heard of them simply as NPK and each has its role.

  • Nitrogen (N) is essential for the development of plant protoplasm. Protoplasm contains the genetic material of a cell, controls its activity and serves as a catalyst for other minerals. Nitrogen is also part of the chlorophyll molecule, which gives plants their green colour and is heavily involved in creating food for the plant via photosynthesis. Plants absorb nitrogen more than any other nutrient.
  • Phosphorus (P) is essential for the division of cells and the development of the growing tip of the plant. It is also responsible for harvesting the energy of the sun’s rays and using them for growth and reproduction. You already know this process as photosynthesis.
  • Potassium (K) helps move nutrients, water and carbohydrates in the plant tissue. It also activates lots of enzymes such as sugar transportation, protein synthesis, N and C metabolism and so on. K is responsible for the plant’s immune system, if you will. It strengthens the plant’s resistance to disease and also protects it from harsh weather by strengthening the root system against wilting.

NPK are usually the first nutrients that will become scarce because the plants will use large amounts for their growth and survival. These elements can also leach from the soil naturally during heavy rains or long hot seasons. Besides NPK, some other important nutrients your soil should have are magnesium, sulfur, and calcium as well as small quantities of manganese, iron, zinc, boron and copper.

On the other side, when the nutrients aren’t enough, the plants will use up all the reserves very quickly. Afterwards, their growth will slow down significantly or even stop altogether. Their leaves might turn yellow and death of the plant becomes a real possibility. That’s why many people use fertilisers to make up for the missing nutrients. You might need some too, but to know how much and of what brand, check the fertiliser calculator by the Government of Western Australia.

Proper soil PH to grow vegetables

Soil pH is simply an indicator that shows you the acidity or alkalinity of your soil. The pH scale ranges from 0 to 10. Soil under 7 is considered acidic, and above 7 – alkaline. Levels under or beyond the standard will affect the regular growth of your plants. Some plants actually prefer levels below or above the average, but the majority don’t. So, what is the standard pH level for your soil?

In Western Australia, for example, the soil ranges from 4 to 8.5 pH. In the coastal and metropolitan areas the soil tends to be more alkaline (above 7 pH). And inland areas tend to have acidic soil (under 7 pH).

Most soils’ pH levels vary from 3.5 to 10. In areas where rainfalls occur more often, the pH levels range from 5 to 7. On the other hand, dry areas have soil pH from 6.5 to 9. On average, most plant nutrients are available at levels between 6 to 7 pH, so these levels can be considered most favourable, especially for vegetables.

But how do you know the pH levels of your soil?

How to measure the pH levels of your soil

This is an easy DIY method you can do at home using vinegar and baking soda. It will reveal whether your soil is relatively acidic or alkaline. Mind you, if you want more information and a full picture of your soil composition, you should find a soil testing lab. With that said:

  1. Obtain a soil sample – use a hand trowel and dig at a depth of about 15cm (6 inch). Dig up dirt from several spots in your garden. This will give you the average soil sample.
  2. Clean soil sample – remove any sticks and stones and break large clumps from the samples you’ve obtained.
  3. Mix soil and distilled water – mix your soil with distilled water in a clean glass container. Stir until the material becomes mud.
  4. Add vinegar to the mix – add about 1/2 cup of vinegar and stir. If the mix fizzes, and creates foam or bubbles, then you can be sure your soil is alkaline
  5. Add baking soda instead – If nothing happens after you add the vinegar, do the whole thing over again, but this time instead of vinegar, add baking soda. If it fizzles or releases bubbles, then your soil is acidic.
Alternative method would be to get a little bit of soil, mix it with distilled water, let the solution rest, then filter it through a paper filter, and test with pH strips.

Now when you know the pH levels, you can adjust them via fertilisers according to the vegetables you plant to sow. Keep in mind that once you adjust pH levels, you should be monitoring and maintaining those said levels.

The levels of alkaline soils change because of the rock minerals the soil is formed from. Too much fertiliser use can also change the levels drastically in the opposite direction. The amount or lack of rainfalls will also be a factor. All in all, that’s why you should monitor the pH levels.

Ways to improve garden soil

If you plan to plant your veggies directly into the soil and not in a raised flower bed, you need to work on your soil if it has low water retention, poor water drainage, compaction or low fertility. A lot of Aussies have issues with clay and sandy soil. This is why we’ve created an extensive guide on how to improve the quality of your soil. Here are a few methods you can try:


You cover your plants and the top of the soil with much. It preserves the much-needed nutrients, reduces weed infestation and invites earthworms. Mulching also helps to improve the water conversation of the soil. Just remember that it breaks down over time, so you need to add fresh layers when the time comes.

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Soils, especially clay soils, get compacted easily, and frequent foot traffic also contributes to the problem. Why is this bad? Because organisms in your soil need air to survive. Soil compaction also leaves no room for nutrients and water for the plant root system. You can aerate either with the help of a specialised machine or by hand using a garden fork.


Although there are many fertilisers on the market, it’s always good to improve your soil via natural means such as composting. You not only save a few dollars, but you also have a wide variety of natural matter to feed your soil. Some examples of natural matter include grass clippings, coffee grounds, eggshells, fruit and vegetable scraps, old shredded newspapers and many more.

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Change pH levels

If you want to decrease the pH levels of your soil, you need to add sulphur, aluminum sulfate or sulfuric acid. On the other hand, if you want to make your soil less acidic and increase the pH levels, you need to add a material containing some form of lime. The finer the lime particles, the better.

There is a proper time when you should apply the fertiliser, and that is autumn. Also if you want to adjust the pH levels in the spring, do it at least 3 weeks before planting. That way the product will have time to do its job.

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Best soil mixes for raised garden beds

If you don’t want to wait for the pH to reach optimum levels, you can always create your vegetable garden in raised beds. The greatest benefit to these is you have complete control over the soil. But you can’t use just any soil. You need the best soil for your vegetable garden in a raised bed, and you will get that by mixing.

50% compost and 50% local topsoil

You can either create your own compost or purchase it. The advantage of making your own is that you save some money, and you know where the compost came from. If you decide to purchase, do your research on different brands and levels of quality. The best quality composts should contain the well-known NPK nutrients and many other micronutrients and trace minerals.

Your local topsoil should be of good quality as well. Choose topsoil that has been screened to reduce clumps.

Sheet composting

Also known as lasagna gardening, this method is perfect for raised beds and is more affordable too. Start by placing straws, twigs and leaves at the bottom of the raised bed. You can also add organic waste such as eggs shells, tea leaves and coffee grounds, but no meat. The meat will attract stray animals and pests. Layer the components until you’re 15-20 cm from the top of the raised bed.

Fill the last few centimetres with bagged soil. This kind of soil contains no dirt and allows water to drain easily. The materials underneath the topsoil will decompose gradually under the heat, air and water and release nutrients. You can add new layers of compost to make up for levels lost to soil compaction.


  • Measure your soil’s pH levels to determine if it’s alkaline or acidic.
  • Improve your soil by mulching, aerating, adding compost and changing the pH levels.
  • Use soil mixes if you decide to go with raised garden beds.
  • You can always hire professional gardeners to help you with soil improvement and garden maintenance!

So, how was your experience in creating your vegetable garden? Let us know by commenting!

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