How to improve & prepare your soil for planting

How to improve your soil

“To be a successful farmer one must first know the nature of the soil.” – Xenophon, Ancient Greek philosopher and historian, circa 430 – 354 BC

The first thing to remember is that soil is NOT dirt – it’s a live, organic matter, ideally teaming with microbes. In order to get the most out of our gardens, whether that’s more flowers, bigger veggies, or increased resistance to pests and diseases – we need to feed and enrich our soils. 

There are plenty of ways to do this, but the simplest and most effective way is to add organic matter. Incorporating organic matter into soil can improve its structure, nutrient content, and water-holding capacity, all of which directly benefits our garden!

Determining your soil structure

A good place to start is knowing the soil type in your garden. Different plants like different types of soil, but for the most part somewhere close to a loam is ideal. Loam is a rich, crumbly soil – the ‘perfect’ soil structure. It consists of roughly 40% sand, 40% silt, and 20% clay. 

Sand particles are the largest of these three components; they provide good aeration and drainage as they don’t hold moisture. Clay particles are the smallest and can easily be compacted (hence making great bricks!), but aren’t so great for allowing moisture, air and roots through. Clay, however, holds the most nutrients of the three, so it’s an essential pillar to soil health. Silt helps clay and sand mix more readily – it has better moisture retention than sand, and fewer nutrients than clay – silt is the middle man! The right blend of all three is needed to create the ideal loamy soil composition.

The beauty of loam is its loose crumbly texture; effectively providing the plant with nutrients, moisture, and pockets of air for oxygen. It allows roots to easily spread and access the nutrients and moisture they need. This is what you’re aiming for!

To determine your soil texture, rub a moist (not wet) handful into a small ball in your hand and give it a good squeeze:

• Clay soil will hold its shape and be sticky
• Sandy soil will feel gritty and fall apart when you open your hand
• Silty soil will feel slippery and smooth, and will hold its shape (but not as firmly as clay)
• Loamy soil will hold its shape, and crumble when moved

Autumn and early winter is an ideal time to add some rich organic matter into your soil. This replenishes nutrients after the intensive spring & summer growth seasons, and fortifies the soil for the upcoming winter period. 

Compost, manure, leaf litter, and grass clippings are all great sources of organic matter. Usually a 2 inch layer will do it – dig it down into the top few inches of soil. If you have a predominantly clay or sand base, you might need to repeat this a few times throughout the year. 

Tip: An easy way to determine basic soil health is to check for earthworms. The best time to do this is in spring, when the soil temperature has increased and its surface is moist, but anytime (ideally not after rain) would give you an indication of what’s happening below the surface. Use a shovel to dig up about 1 cubic foot of soil. Place the soil on a piece of cardboard, break it apart, and look for earthworms! 10 or more earthworms indicates healthy soil. If you find fewer than 10 worms, it’s time to add more organic matter.

Organic matter

Not to be confused with organic gardening, organic matter is derived from living things – mainly plants but sometimes of animal origin – and ideally will have a favourable carbon:nitrogen ratio. We recommend making your own organic matter, and you can do that in several different ways – composting, bokashi, and worm farms are the three most popular at-home methods. 

Home compost bins are a great way to deal with both kitchen and garden waste. You want to aim for 30-50% ‘green’ – think lawn clippings, kitchen scraps and manure to feed the microorganisms, and the remainder should be ‘browns’ such as cardboard, prunings, wood chips, or dead leaves. 

Garden compost can take anywhere between 3 months and two years to reach maturity; once ready it should be a rich, dark brown colour with a crumbly texture. Hot compost bins like the Aerobin can speed up the process as they keep the compost warm even throughout winter. 

Bokashi is perfect for small spaces or apartment living, where you don’t have garden waste to process. Unlike regular compost bins, the beauty of bokaski is that it can take almost any organic kitchen waste – including citrus, dairy, meat and small bones! Ideally you have 2 bins for continuous use, some bokashi bran or spray (which contains effective microbes) to ferment the waste, and somewhere to bury it once it’s done. The bokashi waste can go into a compost bin for further cooking or treating, or be dug into a channel in the garden to break down over time.

Worm farms are a fantastic mix of the above. They handle most food scraps and some garden waste, but not quite like a traditional compost bin. The best part of a worm farm is the worm castings and ‘worm wee’ – packed full of microbes and nutrients, your garden will love you for it!

Other soil amendments

While adding organic matter is our core focus, there are some additional measures you can take to support your soil health. Some of these include:

• Use cover crops: Cover crops can help improve soil health by adding organic matter, fixing nitrogen, and preventing erosion. In the vegetable garden, maintaining good soil conditions is essential for a productive harvest. Green manures are planted in the off-season and turned into the soil to add organic matter and nutrients. This practice can significantly enhance soil health over time, leading to more vigorous plant growth and higher yields in the growing season.
   
• Rotate crops: Crop rotation can help reduce soil-borne diseases and pests, and improve soil fertility by alternating crops that have different nutrient needs.
   
• Mulch: Mulching is a good idea for maintaining soil health and improving the overall garden ecosystem. Adding layer of organic material, such as straw, wood chips, leaves or grass clippings, spread over the soil surface can help retain moisture, regulate soil temperature, and suppress weeds. As the mulch breaks down, it adds organic matter to the soil, enhancing its structure and fertility. Mulching is particularly beneficial in vegetable gardens, where consistent moisture and nutrient levels are crucial for the best vegetable yields.
   
• Use natural fertilisers: Natural fertilisers such as bone meal, blood meal, and fish emulsion can add nutrients to the soil without the negative environmental impact associated with synthetic fertilisers.
  

Improving clay soils

Heavy clay soils can give gardeners a hard time due to their compact nature, which can stifle plant roots and impede water drainage. The good news is that incorporating plenty of organic matter, such as compost, aged manure and gypsum, can transform heavy clay into more friable soil.

Knowing your soil pH

Soil pH is another key component of soil health to consider, as it can affect the availability of nutrients to your plants. Soil pH levels are measured on a scale of 0–14, where 0 is very acidic soil, 7 is neutral and 14 is very alkaline. The ideal pH for most plants is around 6 to 6.5, so this is the sweet spot you want to aim for. If your soil is too acidic, you can add an amendment such as lime to increase the pH. If it’s too alkaline, you can add an amendment such as sulfur to lower the pH. 

You can buy soil pH test kits for a precise reading (such as this one), but if you don’t want to wait here’s a simple DIY experiment you can try (this can be a fun activity to do with kids!).

You’ll need: 2 bowls, a cup of soil, ½ a cup of water, ½ a cup of baking soda and ½ a cup of vinegar.

1. Place 2 tablespoons of soil into each bowl
2. In one bowl, mix in ½ a cup of water & ½ a cup of baking soda
3. In the other bowl, mix in ½ a cup of vinegar

Notice if either mixture foams or fizzes. If the baking soda mixture fizzes, your soil is on the acidic side. If the vinegar mixture fizzes, your soil is more alkaline. If nothing happens to either mixture, you have neutral soil – which is where microbial activity is greatest.

Plants are able to absorb more nutrients at a slightly acidic pH (around 6-6.5). However, all plants are different so it’s best to do some research and amend your soil according to what you want to grow.

Planting in raised garden beds

If your garden struggles with poor soil quality, creating a raised garden bed can be an excellent solution. Raised beds allow you to control the composition of your soil more precisely, ensuring it is rich in organic matter and free from large rocks or other obstructions. Fill your raised bed with a mixture of topsoil, compost, and aged manure to create a nutrient-rich soil that supports robust plant growth throughout the growing season. Raised beds also improve drainage, making them ideal for regions with heavy, wet soil.

Summary

Remember that good garden soil is the foundation of a thriving garden. Regularly adding compost and organic matter, conducting soil tests, and adjusting your practices based on soil conditions will lead to healthier plants and more bountiful harvests. Whether you’re dealing with bare soil in a new garden bed or enhancing an established garden, these steps will help you create the perfect environment for your garden plants to flourish.

Once you’re familiar with your garden’s soil structure and soil pH, it’s easy to make a few simple soil amendments. Lots of organic matter is your best friend when it comes to soil improvement! Your plants will thrive in healthy, microbe-packed soil. Just remember, like most things in the garden, good things take time and can’t be rushed. Once you’ve added your organic matter, sit back and let the microbes do the hard work.