A comparison of commonly used mulch

Mid Spring is a good time to begin to think about protecting your soil from the impending heat and giving your plants a boost of nutrients that mulch can provide.

Over the past few years I have used a variety of mulch products on my garden and have now settled on a select few that I also use in the Kindergarten and family home vegetable garden set ups I complete. I have selected them based on my core objectives for vegetable garden mulch in my garden. They must be:

1. Organic – eg: untreated with chemicals

2. Easy to apply and fast to break down – eg: within one year.

3. Able to provide stability for soil temperature and moisture content.

4. Adding nutrients or other beneficial properties to the soil

Why add mulch to a vegetable garden?

Mulch is important to add to the soil for the following reasons:

• Shelter for soil dwelling bugs
• Maintenance of soil temperature and moisture
• Provides organic matter and enhances the soil’s ability to hold nutrients and water
• Prevents erosion of top soil
• Helps suppress weeds – in some instances

There are various grades of each of the mulches listed below – some are more processed than others to a finer consistency. Some are course. In the instance of pea straw I have used very course, fine and also pellets. Each have their own benefits and draw-backs. The main difference I have noticed is in the amount of dust and seed generated and how quickly they decompose.

The question “which mulch is best to use in a vegetable garden?” is subjective. It depends on the purpose of it’s application.

It is your garden, you need to decide what you want the mulch to achieve to assess if it is the “best”. Some questions to help you determine what you want to achieve may include:

• Are you are  seeking a stable soil temperature and to minimise moisture loss in the warm months?
• Do you want to add organic matter to your top soil?
• Do you need to aerate a heavy soil?
• Do you need a heavy cover to allow the soil underneath to regenerate?
• Do you want to give the plants a nutrient boost?
• Do you want a mulch that is slow or fast to break down?
• Do you have a neat structured garden or a more rustic free-form approach?

When I asked my community on both Facebook and Instagram which type of mulch they like to use the answers came back with equal favourites: pea straw, lucerne and sugar cane mulch.

Some people use layers of each to combine the properties of various mulch types. Some people also mentioned they like to use leaves as mulch. I personally prefer to add leaves to the compost and worm farm rather than adding them straight to the top soil. This allows them to decompose prior to use.

When  I checked in with my social media community I found that many people responded that they like to use x or x mulch, meaning they select one of two options depending on what is available at the time they need it and possibly based on a cost comparison.

This is what vegetable gardening is about – find what works for you in your vegetable garden and repeat it if it works, change it if it does not. I encourage you to test a few different mulches and see which you prefer. There is no right or wrong mulch to use. Find the one most suited to your requirements.

Straw – Wheat, Barley or Oat

Created from the plant stalks. The seed heads have been removed so they will not seed in the garden. These can take a little while to break down compared to the finer chopped sugar cane mulch. It is a more rustic look in the garden, not as neat around the plants. As you can see from the image above it is difficult to smooth out all the stalks around the plants. It is an effective mulch for deflecting heat and retaining moisture and is an economical choice. It can be purchased from farm supply stores. It can be tricky to find out if the source was grown using organic techniques if that is a concern for you.

Hay

Hay is cut when the grass is green and dried. The whole plant is used, rather than just the stalk as is the case with  straw. It tends to be thicker, but finer than straw in the instances I have used it in the garden. I find it works in a similar way to straw but is a little easier to apply around plants. As with straw it is difficult to determine if the source plants were organically grown. Hay is another product that can be purchased from farm supply stores.

Peastraw

I have tried various types of pea straw – rough varieties such as illustrated in the straw image above as well as finely chopped varieties that are bagged and available from most large nurseries and hardware stores as well as in a compressed pellet from Majors Mulch.

I have used the thick rough variety to line the vegetable crates I use in my vegetable garden set up service if regular straw is unavailable. The problem with this product is that it is filled with seed. This means you end up with peas sprouting all over the garden bed. Some people love the bonus pea shoots, I’m not so keen. If I wanted to plant peas I would have… I think they make the garden bed untidy – or more untidy than usual… These peas are also drawing on the nutrients in the soil that I want the new plants I have selected to have available for use.

The finer variety available from most hardware stores and nurseries is suited for use as a top soil mulch, as opposed to a buffer to the wood of a garden bed as describbed above. It is readily available, not expensive and easy to spread. It doesn’t tend to sprout so I assume it has been heat treated in some way because it is generally labelled as organic.

The third type of pea straw I have used is a compressed pellet from Major’s Mulch. It is dust and seed free and is easy to apply and breaks down beautifully. I choose to use these Major’s Mulch pellets in my customers gardens. We added it to the paths of the garden below. It is springy and fluffy, creating a wonderful seal over the soil. In saying that, the owner of this garden is keen to add straw over top of the pea straw in a bid to make it less springy. Because it is lightly applied it will degrade reasonably quickly. There are layers of hessian, cardboard and newspaper underneath the paths shown in the image below to keep them weed free. This is a high quality product so is best used for a top soil application. I chose to use it in this garden primarily because I absolutely trust the source to be chemical free and organic and the owner is sensitive to chemicals.

As with all products you choose to test, and then use ongoing in your garden, your choices are based on the results you achieve.  I seek a trustworthy product of premium quality that I am happy to use and share with my customers.  I want the product to add something to the garden soil. Two years ago I met Sarah from Major’s Mulch. She has created a range of organic mulches and compost from materials grown on her farm in NSW.

The products I select to use in the vegetable garden set ups I complete have been tested and carefully selected from numerous brands, monitoring, interviews and discussions, including this one. If you are based in the Geelong, or Bellarine areas you can order Major’s Mulch peas straw and lucerne pellets and complete compost from me by emailing your request to [email protected]

Lucerne

Lucerne is said to be the premium mulch if your garden requires a nutrient boost. As expected it is the most costly of the mulch options.

Lucerne is quick to break down in the soil providing a big boost of nitrogen as it does so.  Nitrogen provides strong healthy leaf growth in herbs and vegetables, as well as other plants. Some gardeners like to add it in a light layer and then add another mulch over the top. the image above is of Major”s Mulch lucerne pellets. They are applied to the soil in a thin scatter and then watered well. they expand as they absorb the water. Because they are fast to break down you may choose to add another type of compost on top after a couple of months.

Sugar cane

Made from the dried sugar cane leaves in QLD and readily available in Australia from hardware stores and nurseries. It is an economical option, easy to apply but best to do so with a face mask as it is a dusty application. It is light and prone to being blown around in hot dry winds. Once applied it is a good idea to wet it down thoroughly to allow it to settle.

 

Wood chips:

The density of wood chips, unless they are finely chipped, means they take a long time to break down. It is recommended that chips added to the garden are not from freshly cut trees . I’m not a fan of using these for a vegetable garden although I have used them in a regular garden area. I have spoken to a number of people in my community who have used them with great success in a vegetable garden, especially in areas of Australia where water shortages are an issue. I am told that a thick layer retains the moisture in the soil well.

A few uncommon mulches:

Lemongrass

I cut the lemongrass bushes back at the end of summer and the end of winter each year. The grass I remove I add to the bed that is filled with blueberries. The plant is said to repel mosquitoes so is a good addition to the garden. The leaves are sharp on the edges so beware as they cause itchy, painful scratches if they come in contact with your arms. You may wish to  keep some aside to dry for making herbal tea.

Rosemary and Lavender cuttings

I have been using cuttings of both rosemary and lavender with great results to mulch around kale and bok choy as a way to deter the white cabbage moth. The strong smell is said to deter them. I have noticed that this does indeed seem to be the case. In addition to being a good choice from an organic pest control perspective, it costs nothing and saves space in the green bin when you do a tidy up of any plants in your garden. We have a large lavender hedge and the need for a trim coincides with the influx of white cabbage moth. For other tips on deterring this garden pest read this post.

As I learn more each year I grow in my vegetable garden and help others with theirs, I am learning more about aspects of soil, companion planting and rotation. For the last couple of years I have been measuring and monitoring the influence  flowers have on a vegetable garden harvests and to attract beneficial insects.

This post is about sharing my experience to date with different types of mulch I have used. I am working on discovering the properties, if any, the rosemary and lavender add to the soil as they break down.

What effect do you want the mulch you add to your summer garden to have?

With the objectives outlined at the start of this post, my choice is to use lucerne pellets once a year to give the plants a nutrient boost and pea straw once a year. I regularly mulch in mid Spring and lightly at the end of Winter.

NOW is the time to mulch your vegetable garden prior to Summer commencing. Have you thought about where to get your mulch and which one you would like to use?

It may take some time to determine the best mulch for your garden. To work this out record your garden progress over a number of seasons in a garden journal. The Vegetable Garden Workbook helps you to discover what grows best and the routines that work best in YOUR vegetable garden, resulting in greater harvests for your meal table. Find out more about the Vegetable Garden Workbook here.

Do you have another type of mulch not listed here that you use regularly? Please tell me in the comments below.