Have you been growing your vegetables or herbs in raised garden beds for a season? If so, you might be wondering what you need to do to get your raised beds ready for planting next season’s crops. This blog post walks you through all aspects of preparing your raised garden beds for planting, to help you achieve amazing results and delicious, nutrient dense veggies and herbs. These principles can also be applied to amending the soil of your in-ground gardens and pots/containers. 

Raised garden beds are one of my favourite way to grow vegetables. They look great, they help to retain moisture and they prevent grass and other weeds growing through your veggies. Raised garden beds can really optimise your use of space, and can be made in different shapes and sizes.  If you’re looking to build your own raised garden beds using recycled materials, check out my blog post here.

As with any growing medium, the soil in your raised garden beds will need a little bit of love and care after a season of producing an abundance of food. Many summer crops are known as ‘heavy feeders’, meaning that they require a large amount of nutrients to grow. These nutrients are taken from the soil through the roots and used to grow healthy plants and fruits/vegetables for you to eat. Because the plants take these nutrients from the soil, there are some steps you should take to replenish these nutrients and create healthy soil for your next growing season. You may even need to build up your soil level if your beds have slightly sunken like mine do.

You can also use these tips when setting up a new garden bed to make sure that you are providing your soil, and therefore your plants, with a great head start!

The importance of soil health

Soil health is one of the most important aspects to growing plants of any kind. Healthy soil = healthy plants = healthy people. So what do I mean by healthy soil?

Healthy soil, much like a healthy human body, contains a whole ecosystem of living microorganisms. This complex system contains a diverse range of flora and fauna, organic matter, inorganic matter, minerals, and other nutrients. 

Healthy soil is soil that is filled with living, breathing microbes that work to break down organic matter (any living or dead plant or animal material), and convert it into plant available nutrients, improve water holding capacity, and assist the plants to take up the nutrients they need to thrive.

What are the indicators of soil health?

There are several indicators of soil health that you can take note of when decided what kind of amendments you need to make in between growing seasons or in between succession crops. Some of these indicators include:

Soil colour – the colour of the soil can give us a good idea of how much organic matter is present in the soil. Generally, the darker the soil, the more organic matter, and the greater the soil health. Ideally, you want a nice rich, dark looking soil to grow your vegetables and herbs in your raised bed garden

Biological activity – you want your soil to be ALIVE! Healthy soils are biologically active soils. Essentially, you want to see the presence of earthworms, earthworm castings, dung beetles, springtails etc. To increase the presence of soil biology, the best thing you can do is increase their FOOD. Soil biology feeds on organic matter, so adding things like compost, leaving roots in situ, or mulching your garden feeds your soil microbiome.

Soil structure – soil structure refers to the ability of the soil to form ‘aggregates’ or clumps, which are held together by organic matter, root exudates and fungal structures. Soil structure is strongly correlated with soil organic matter. A good soil structure shows good aggregation (the ability of soil particles to be held together) with plenty of air spaces and organic matter for microbes to thrive, this also allows good drainage. The best way to improve soil structure is to leave the roots of plants in the soil when you are ready rotate your crops. I prefer to implement minimal till gardens as this prevents the soil from being overly disturbed and protects the soil structure. If you need a more friable soil for growing root crops such as carrots, you can work the soil a little more, but try to keep this to a minimum.

Soil moisture – When you dig into the soil, you want to feel that the soil is moist. You cannot have life without moisture, and soil moisture is a key component to soil health. It’s important that, if you don’t receive adequate rainfall, you ensure that you are watering your raised bed vegetable gardens frequently. This is more important in summer months, when plants are using up available water quickly.

How to improve soil health

As you may have noticed from reading above, soil organic matter is one of the key factors to creating healthy soil. Organic matter improves soil structure and biological activity, as well as improves water holding capacity by acting like a ‘sponge’. Organic matter can improve both sandy soil and clay soil, and I believe that the path to healthy, fertile soil is to add organic matter.

Types of soil amendments

Compost

Compost is the end product of a process that takes organic matter (living or once living material) and converts it into a nutrient rich and biologically active soil. Adding compost to your raised bed vegetable garden adds essential nutrients, improves soil biological activity, increases water holding capacity, and can greatly improve plant growth.

You can find compost at your garden supplies store, local nursery, or you can make your own. Chances are you already make your own compost if you have a vegetable garden, as these two things go hand in hand! If using your own homemade compost, ensure that it is adequately broken down and ready to add to your beds. You want your compost to be a rich, dark brown colour and it should be easy to crumble with your fingers. If you see pieces of food or your compost is wet or smelly, it is not yet suitable for the garden.

Manure

Manure is a superfood for your soil! Like compost, manure has many benefits when added to the soil including increasing nutrients, adding organic matter and improving soil structure. Manure contains a host of beneficial microbes ready to get to work to provide your plants with the vital nutrients they need to thrive. Manure comes in many different forms, and different manures have different properties due to each animal’s varied diet and means of digestion.  

Cow manure is an excellent soil conditioner and high in organic matter. Cow manure is relatively low in nutrients due to the cow’s efficient digestion, however it is perfect for root vegetables such as carrots, beets, onions and potatoes.

Sheep manure is another popular choice for home gardeners as it is also a great soil conditioner. Sheep manure contains higher amounts of potassium than cow manure and is ideal for using in beds where above ground crops such as tomatoes, peppers, beans, brassicas and cucumbers will be growing.

Horse manure is also richer in nutrients than cow manure, and needs to be composted/aged before using on the garden. Horse manure often contains weed seeds that can germinate and affect your garden. I don’t believe horse manure is the best choice if you are trying to avoid weeds.

Chicken manure is another popular soil amendment due to it’s very high nutrient content. Chicken manure is especially high in nitrogen, phosphorus and potassium. Chicken manure must be composted before adding it to the soil, otherwise is can ‘burn’ plant roots. You can also buy poultry manure in a ready to use pelletized form.

IMPORTANT: Manures from cats, dogs, humans and pigs are not recommended as they can contain harmful bacteria and other pathogens. These should not be used on edible plants. There are specific ways in which these manures can be composted, but this is a topic for another day!

Blood and bone

Blood and bone is a nutrient rich, organic fertiliser derived from animal by-products. The blood and bone meal is sourced from abattoirs and used to make an incredibly nutrient-rich soil amendment that most plants love! This is a slow release fertiliser that continues to feed your plants over several months and needs to be applied sparingly to prevent certain nutrients from building up and creating an imbalance in the soil. You also need to be mindful that some pets and wildlife may be quite interested in the smell (and taste) of this product. Always water it in well after applying, otherwise you might find your dog trying to lick the dirt like mine!

Worm cast

Worm cast, also known as vermicast is another superfood for your garden! Worm cast could also be thought of as another form of manure, seeing as worm cast are actually worm poo! The properties of worm cast are quite amazing, and are known to improve plant health, promote disease resistance and retain moisture. Worm cast contains important minerals and microbes which promotes healthy fertile soil and therefore healthy plants.

Mulch

Mulching your garden serves several purposes, including adding a layer of organic matter, protecting the bare soil from erosion, reducing moisture evaporation and insulating the soil against extreme heat and cold. Mulch acts as an important groundcover on the soil. A lack of groundcover can cause the soil to dry out and you may find that a hard surface is formed on top of the bed. This can prevent water infiltration and result in hydrophobic soils (soils that repel water). You can mulch year round, however, you may wish to reduce or avoid mulching if planting fine seeds like carrots or lettuce as these will struggle to emerge from under a thick layer of mulch. If you wish for your soil to warm up in spring, removing some of the mulch can speed up this process.

Grass clippings and leaves

Grass clipping can be used to boost the organic matter in your soil. I prefer to wait until the are dry before adding them to my garden bed as the high nitrogen content may harm small seedlings. You can uses grass clippings as either a mulch, or you can incorporate them into the soil with a garden fork. Simply collect them in a lawn mover catcher, lay them out to dry and turn them every few days. Once they are dry you can use them in your preferred way.

Leaves can be used in a similar way. Autumn leaves can be used as a mulch or incorporated into your garden beds to give the soil a nice boost of organic matter. 

Green manure/cover crops

If you have the space to allow one or two beds to rest over the winter months, green manure or cover crops are an incredible way to prepare your raised beds for your summer vegetables. Green manure is a method of planting specific annual plants such as legumes, buckwheat and rye, allowing them to grow, and then digging the whole plants back into the soil. This method supercharges your soil by adding in essential nutrients such as nitrogen, and boosts the soil microbiome. Returning the plant material back to the soil increases the soil organic matter and leaves you with an incredibly healthy soil that will support your summer plants to thrive.

A note on synthetic fertilisers and additives

I prefer to steer clear of synthetic inputs for several reasons.

• Synthetic, or chemical fertilisers harm soil microbiology. This is the opposite of what we are trying to achieve.
• Synthetic fertilisers are water soluble, making them susceptible to leaching. As water moves through the soil profile, the fertilisers go with it. This can have significant negative effects on our wider ecosystems.
• Synthetic fertilizer is expensive. I find it much cheaper to use products that are found in nature or can be made at home. Things like manure, compost, blood and bone and mulch are all examples of this.

My simple steps for how to preparing raised garden beds for planting

I take these simple steps twice a year to amend my raised beds and improve the quality of the soil for healthy plants and a bountiful harvest. I find that a good time of year to do this is early spring and early autumn in my cool-temperate climate.

1. Remove plants by cutting at the base of the stem rather than removing the roots. Remove any drip irrigation from your raised bed gardens.
2. Add rich compost and aged/composted cow or sheep manure.
3. Add blood and bone fertiliser and worm cast.
4. Using a garden fork, gently incorporate the amendments. Try not to overwork the soil, you don’t want to disturb the soil structure too much.
5. Cover the garden bed with mulch and water in well. 
6. Allow your garden bed to rest for 7-10 days before planting. Replace your irrigation system if you have one and continue to water your beds every couple of days until you’re ready to plant. This will keep the soil life happy and healthy!

My frugal tips

There are so many things you can do to save money in the garden:

• Use what you already have – if you’ve got lawn clippings, fallen leaves, animal manure/bedding or compost, use these before going out and buying anything new.
• Buy in bulk – it is generally cheaper to buy garden inputs in bulk such as compost, mulch, blood and bone etc if you need large quantities. You could also buy a larger amount for a cheaper price and split it with a friend.
• Connect with your local community – ask around to see if anyone has a worm farm, or maybe some cattle you can collect manure from. Perhaps someone has a whole lot of autumn leaves they don’t know what to do with! You could help them out by cleaning them up and using them for your garden. Trading and bartering is always encouraged.
• Green manure is one of the most cost effective ways of boosting your soil health ready for planting. Yes it takes some time to grow and incorporate, but after the little effort of sowing the green manure seed (which is inexpensive), there is very little to do apart from wait.

Let me know if you found this article helpful, happy planting! 🙂